Simple Guide to Battery Life in your RV


Batteries exist in an RV because they are a necessity. Many of the systems simply cannot function without a battery. The 12-volt DC battery bank powers all interior lighting, climate controllers, exhaust fans, heater blowers, and many other areas.

My first RV was a 5th wheel, and it had a single 12-volt deep cycle battery. This battery powered the lift jacks, and I quickly discovered that it would not do so for very long. The battery was charged while the 7-pin connector was attached to the pickup, or while the RV was plugged into shore power.

My next RV was a 2008 Fleetwood Discovery with a much more advanced system, and one that I never fully understood. It had a flooded cell battery system and I learned after 3 years that they require water. I had to replace every battery because I had ruined all 4 batteries. I also had a huge mess in the battery bay from the corrosion caused by the off gassing. I spent a lot of time cleaning it up when I replaced the batteries, but was unaware of AGM batteries, and replaced it with flooded cell again. The problem reoccurred 2 years later, but at that time I was trading it in and didn’t care.

I custom ordered a 2013 Newmar Dutch star 4347. One of the specials I requested at the time was an upgrade to AGM batteries. During this time, I did a deep dive into the entire 12-volt DC power system and was amazed at what it could do, and how simple it really was, once it was fully understood.

I am writing this guide to share the knowledge I have gained. Most of what I have learned comes from others.

Ronnie F. Moller, Jr.

Who is this guide for?

This guide is written based on my experience with Newmar coaches utilizing the Magnum inverter/charger. It will also apply to any other manufacturer that has the same or similar setup. The Basics section will apply to 90% of RVs on the market, including the Newmar gas lineup.

Magnum ME-RC

The In Depth is more specific to coaches with a Magnum Inverter/Chargers ME2012/MS2012/MS2812, which includes the Newmar diesel coaches, but not the Luxury diesel line with the Xantrex chargers. The luxury line utilizes both depending on the year, so you need to know which system you have specifically. The simplest way to tell if this applies to you is by looking at the controller for your inverter charger. If you have one that looks like the one shown in Figure 1, then this document applies to you.

This document designed for those that are normally plugged into shore power, but on occasion will be using the battery power and want to be prepared. I use of my generator liberally and have no concerns about over usage of a generator, but there are times I want to limit the usage, such as when boondocking in perfect tent weather. Our family likes to camp on BLM lands near the Pyror Mountain Wild Horse Range. The night time temps in August are typically in the 60F range, and the skies are some of the darkest we have been to. This is true off the grid, and we will spend 2-3 nights camping out there. Nothing ruins the tranquility and peace like a generator running. We manage the generator to run during the day, often while we are out looking for the wild horses. At night, we run the entire coach on batteries. We can make coffee, heat water, shower, and charge cell phones without the need for shore power.

What this guide is not

This guide is not meant to apply to every coach or every situation. This guide does not address solar energy and is not designed for the unique needs for those on solar.

If your coach does not have a generator, or if your batteries do not charge while driving, then you will need to adopt different strategies than what this document outlines.


Battery Capacity / Amp Hours

From the day I started driving a car, I was aware of the size of the fuel tank and closely monitor the gas gauge. I understood how far I could drive before refueling, and never pushed the limits. While this seems obvious for a motor, I didn’t consider doing the same thing for my RV batteries when I first started. After continuously being disappointed with my batteries, I learned that there is an equivalent rating on RV batteries that tells you how much power capacity each battery has, Amp Hours, expressed as Ah.

The Ah rating describes the ability of the battery to provide power over a 20-hour period. If the rating is 100 Ah at the 20-hour rate, then the battery can supply 5 amps for 20 hours. (5×20=100).

Parallel vs Series connections

Using the battery for all 20 hours would result in a completely consumed battery. The life of the battery, or number of discharge/recharge cycles, is based on how low the battery is discharged prior to being full recharged. Each battery manufacturer provides data on life expectancy as it relates to depth of discharge. Generally, one should never discharge below 50% before fully recharging.  Using our above example, a battery with a 100Ah rating should only be used at 5 amps for 10 hours before being recharged.

To increase capacity, multiple batteries can be connected in parallel. This keeps the voltage constant while doubling the Ah. Four batteries rated at 100Ah connected in parallel will deliver 400Ah, or a usable 200Ah based on the 50% guideline. This could be 5 amps for 40 hours, or 20 amps for 10 hours.

Battery Voltages

Newmar coaches, as well as most other RV’s utilize 6-volt batteries because they provide a greater capacity.  In order to bring the battery voltage up to 12-volt, two batteries are connected in series. When two batteries are connected in series, the voltage is doubled while the capacity remains constant.

To illustrate why a 6-volt setup is preferred, consider these batteries:

Option 1 – 12-volt Batteries:
A total of 6  Interstate SRM-24  ($113.95 retail per battery providing 81Ah and weighing 46lbs.) would provide 486Ah, with 243Ah usable at a cost of $683.70 and a total weight of 276lbs.
Option 2: 6-volt Batteries
A total of 4 Interstate GC2-HCL-UT ($142.95 retail per battery, providing 210Ah and weighing 58lbs.)  would provide 420Ah, with 210Ah usable at a cost of $571.80 and a total weight of 232lbs.

Both batteries are similar dimensions, meaning that you need less space to with the 6-volt battery setup for similar power delivery. With the additional money savings, and weight savings, it is easy to see why the 6-volt setup is the way to go.

Battery types

It is important to know what type of battery you have. The most common batteries are lead acid type of batteries, and those are the ones we will be discussing. Less common batteries are the newer Lithium batteries. This document does not cover lithium batteries, but this is a topic you should explore if you are looking at the ultimate boon docking setup.

 Lead acid batteries are designed either for starting or deep cycle. This document is focused on the deep cycle type of battery, used for inverting 12v power to 120v house power. In this application, starting batteries should not be used or considered. Starting batteries have a higher plate count and deliver greater amounts of energy in quick bursts. The plates in a starting battery are much thinner and are subject to warping when fully discharged. Once warped, the plates can touch and cause a serious electrical short with thermal runaway. For this reason alone, one should avoid using a starting battery on the house side of RV electrical system. For more information, see this link:

Deep cycle batteries have much thicker plates and can handle the deep discharge without danger. As a result, deep cycle batteries deliver less instant energy but have a greater endurance.

Deep cycle lead acid batteries are commonly found in 2 types. Flooded (Wet Cell) and Absorbed glass mat (AGM).

Flooded Wet, serviceable

The standard battery Newmar includes with most coaches is the 6-volt flooded wet cell battery which is serviceable. A serviceable battery requires that the water levels be maintained. The advantage of this battery is the low cost and high amount of energy available for continuous usage. These batteries are typically used in golf carts and are designed to be cycled to a deep state of discharge.

Flooded wet cell batteries require a great deal of maintenance. The batteries also are highly corrosive and can be easily boiled if the charger is not setup properly. These batteries do not like to sit for long periods of times without a charge and do not recover well from a very low discharge.  The batteries remain popular primarily because of their high availability and low cost when compared to AGM batteries.


Absorbed glass mat (AGM) batteries are a non-spillable deep cycle lead acid battery. They may be mounted in any position and are maintenance free. AGM batteries do not expel hydrogen gasses like the flooded wet cell batteries do, and as a result there is no loss of either water or electrolytes.

The design of AGM batteries allows for additional plate surface area when compared to the same group size of a flooded wet cell battery, increasing both the burst energy as well as the overall capacity (Ah) of the battery in the same size.

Additionally, AGM batteries have a lower overall resistance, allowing for a faster charge and slower self-discharge. These batteries perform very well sitting at rest fully charged, holding their charge much longer than a flooded wet cell battery.

AGM batteries are generally maintenance free. All this benefit comes at a cost. When comparing similar batteries, the cost often approaches 80-120% more for the AGM vs Flooded wet cell.

Example Interstate Batteries for comparison

Wet Cell: Interstate GC2-HCL-UT ($142.95 retail, 383 Reserve Capacity, 210Ah, 58lbs.)
AGM: Interstate GC2-HD-AGM ($324.95 retail, 475 Reserve Capacity, 210Ah, 66lbs.)

Battery maintenance

All batteries require proper maintenance. Never discharge the battery below 50% capacity. Never store a battery discharged, always fully charge your battery.


All batteries have different lifetime characteristics based on cyclic usage, or the number of times the battery is discharged and recharged. This characteristic is affected by how much capacity is taken from the battery (discharge), the operating temperature, and the charging method. All batteries differ on the number, but all batteries perform better when they are kept cool and are not discharged too deeply. See Figure 5 – Source: for a chart that demonstrates how battery life is affected by discharge cycles.

In order to get the maximum performance, safely from your battery, a clean and tight connection is mandatory. Battery terminal connections should be inspected routinely. There is a lot of vibration that occurs when driving your RV down the road, and the batteries are often exposed to the elements. It is a good idea to clean your battery connections every time you wash your coach, which for me is at the end of every trip, and sometimes more often. While doing this, check your cables and make sure they cannot be moved. If they are loose at all, tighten them.

If you have AGM batteries, then you can stop reading, as your battery does not require any other maintenance.

Serviceable wet cell

Cleaning should be done monthly. If you do not clean them the corrosion will build up very quickly and spread. It does not take long for the cables themselves to become very corroded. Once this happens the only fix is to replace the cables, which can become very time consuming and is not cheap. A mixture of water and baking soda ( 1 Tbsp baking soda to 1 cup of water) is a great way to clean the battery terminals. Use an old toothbrush to apply the mixture directly. Rinse with water.

Serviceable wet cell batteries also require routine fluid checking. This should be done at least once per month, and only when fully charged. NEVER add water to a discharged battery. When adding water, distilled water is the best option. Tap water has other minerals in it that can affect the performance and lifespan of the battery. If you don’t have access to distilled water, tap water is better than waiting or ignoring it. Do not let the water level ever drop below the plates, but also be careful not to overfill. Remember that in the summer the battery will run hotter, causing the fluid to expand. When water overflows (called boiling over), you lose the electrolytes that are in the battery. Not only is this very corrosive, but it also is necessary for the battery to function properly.

Most of the corrosion is caused by the gases leaking from the battery. I have read different strategies for adding mineral oil to the batteries. The theory is the mineral oil will sit on top of the water and prevent the gasses from venting out.  I have never done this and offer no opinion on the subject. This is something you should research and determine if it is suitable for your use.


Most motorhomes will have a combined inverter and charger. Some RV’s will have a converter/charger and a separate inverter. Regardless of the design, the two functions are unique and controlled independent of each other. With a combined unit, a single controller operates both functions under different menu selections.

When does it charge?

The charger requires 120-volt AC power in order to operate. This can be provided by either the generator or shore power cord. Once 120-volt power is present, the charger will engage, depending on the settings. All chargers require proper configuration for the type of battery they are charging in order to properly maintain the lifespan of batteries.

What does it charge?

The charger is responsible for maintaining the house batteries. In most motorhomes, the charger will also maintain the engine battery. This is controlled by an isolating relay that will swap between the chassis and house batteries.

Other Charging methods

While driving, most motorhomes will charge both the house and chassis batteries from the alternator. This will allow lights, heating, microwave, and other 12v items to be used while driving without depleting the battery. The ability to keep up with demand varies by coach. Both of my Newmar Dutch stars have been able to handle very large inverting loads including microwave, refrigerator, television, DVR, laptops, etc. and arrive at camp fully charged. 


The inverter is responsible for taking 12v DC power from the house battery bank and changing it (inverting) to 120-volt AC power. This allows for common household items such as hair dryer, microwave, coffee pot, residential refrigerator, etc. to operate without the use of the generator or being connected to shore power.

All inverters have a maximum rating, expressed in watts. The base 2019 Newmar Bay star sport has a 1000w inverter to operate the pumps, and an optional 1000w inverter for the televisions. The 2019 Newmar King Aire has two 3000-watt inverters and 16 6-volt batteries, allowing for one of the air conditioners to be run from the inverter. The size of the inverter determines how much AC electric power you can use. If you pull too much, the inverter will shutdown with a fault. Running it close to maximum will cause a lot of heat and load on the batteries and discharge them quickly. Typically, items like the coffee pot, microwave, or hair dryer will cause the most load, while TV’s will consume very little load.

When does it invert?

The inverter must first be enabled on the main control panel. Most inverters can safely be left turned on all the time. While turned on, the inverter does consume a small amount of battery even without a load. This is good to know if you are storing your RV without power or need to stretch the battery life. Turning the inverter off will ensure that it is not drawing any power from the battery.

You will need the inverter turned on in order to operate any 120-volt AC device when there is no external power source available, such as shore power or generator. My inverter is always on. I store it connected to 50-amp service.

If 120-volt AC power is present from either the generator or shore power, the inverter will not engage. Some RV’s, including the Dutch star, have a feature called inverter-assist. This will allow the inverter to supplement the power available from the shore cord or generator. This is commonly used when connected to 30-amp service and running the microwave along with the roof air conditioners. The startup of either takes more power than a 30-amp service can provide, and the inverter assist can provide that extra power. This is not an unlimited source of power though, and the batteries will eventually discharge to the point the inverter will shut off.

What is powered by the inverter?

This depends on how the coach was wired. Newmar uses an electrical subpanel from Precision Circuits Inc. This has a separate panel for the inverter circuits. On my Dutch star this supplies all the exposed outlets in the coach, all the outlets in the basement, refrigerator, and microwave.

It does not power the washer, dryer, roof air, electric stove top, basement freezer, or engine block heater. The basement freezer is a 12-volt DC and 120-volt AC device. It is more efficient to run 12-volt DC directly vs inverting to 120-volt, and Newmar wired it accordingly.

My 2019 Newmar Dutch star has a 2800-watt inverter, and on a recent trip I was able to overload it. The combination that overloaded the circuit was running the microwave along with the central vacuum while making coffee. Not the typical work load for most people, and this was the first time I had ever overloaded the inverter.

In Depth

The details provided here are specific to the Magnum chargers and the RC/ARC controllers. See Figure 1 for the controller that must be present. If you do not have this controller, then much of what is described in this section will not directly apply. For coaches with a computerized screen such as Silverleaf, the principals apply but the settings will require translation or interpretation.

One very important note regarding battery connections specifically with Magnum inverters. When disconnecting the battery cables, you must first remove all POSITIVE cables before removing any ground cables. The reason is that Magnum utilizes remote modules that are connected to a network power cable. These devices provide a weak ground signal. If the Magnum loses the primary ground, it will hunt for ground along the network control path and end up damaging all the remote devices. These are items such as the Auto Generator start, the Precision Circuits controller, and the RC/ARC controller. This is a very costly and expensive mistake, and one that is easy to make as it defies how most 12-volt DC connections are handled. When reconnecting the cables, the positive cable should be the last cable connected.

Battery connections

The battery connections must be tight and clean. The next step is to ensure the battery connections are at opposite ends of the battery. See Figure 3 for a proper connection. The positive cable should be opposite of the negative, allowing the entire battery bank to be utilized. Both of my Newmar coaches where delivered with an incorrect battery cable layout. See Figure 6 as an example of the incorrect wiring. Notice how 3 separate cables where connected to different battery cells for the ground, and the positive connection was in the middle cells. The result of this improper wiring is underutilization of the entire battery, as the electrical circuit would take the shortest path, often bypassing other battery cells. This would allow some batteries to discharge while other batteries remain unused. This is very simple to fix by simply relocating the battery connections to opposite ends. Be sure to disconnect the positive cable first and reconnect it last.

Battery Ah remaining / State of Charge

The remaining battery capacity is known as the state of charge (SOC). There are several methods to determine the SOC.  The most common ones used are specific gravity measurements, voltage-based estimation, and current-based estimation.

Specific gravity measurements are not convenient and very few people would use this method. It requires using a hydrometer and testing the level in each cell. This method is primarily used to test a battery that has been fully charged to determine how well the battery is performing.

Voltage based measurements are the most common method used, as it is the only method that is available from a stock RV.  The problem with this method is the measurement will vary based on load. When an inverter is under high load, such as powering a coffee pot or microwave, the instant voltage readings on a battery are unreliable. Using voltage-based methods often gives the appearance of bad batteries, and causes frustrations when boon docking, with short intervals between auto generator starts.

Current based estimation is the most convenient method for a very reliable battery state of charge. This method uses a value from 0-100% to show the amount of battery charge remaining, just like a fuel gauge. Power is measured in both directions to calculate the state of charge. Magnum inverters can use current-based data for AGS and Inverter settings once the ME-BMK and shunt are installed on the system.

Why you need a current-based estimation system

No RV should be without a current-based estimation system. Using voltage-based estimation is highly inaccurate and overly frustrating. To illustrate the difference between a voltage-based measurement and a current-based measurement I setup a test. My battery bank provides 840Ah of capacity with the 8 AGM discover batteries.

Starting with a full charge, I disconnected my shore cord and observed the status with only my residential refrigerator running along with my network and DirecTV equipment. The load was 20-amps DC, and the battery voltage reported 13.1-volts DC. After 5 minutes, the load remained constant as did the voltage. I then turned on my microwave, a GE Profile Advantium, using the convection oven to heat to 350F. The battery status immediately displayed 191-amps DC load, and battery voltage of 12.2-volts DC. I ran this load for 30 minutes. The battery status reported a voltage of 11.1-volts DC.  Many systems would have disengaged the battery by this time, and if AGS is being utilized, the generator would have started. To further stress the system, I engaged the central vacuum putting a 291-amp DC load on the battery bank, with a reading of 10.9-volts DC. I ran this for 5 minutes, with battery voltage readings fluctuating between 10.9-volts and 11.1-volts DC and power loads fluctuating between 178-amps and 291-amps DC. This was based on when the microwave was energizing the heat vs stable.

Using only the voltage-based system, the generator would have auto started, or the inverter would have cut out based on the sustained low voltage reading. When the load was removed, the batteries reported 12.7-volts DC, which shows that they were truly never discharged. In fact, using my current-based measurement, I still had 94% battery life remaining. This was a very high load for a very long time.

This is the reason I said in the beginning of this section, No RV should be without a current-based estimation system.

Documentation for the installation and setup of current-based SOC gauge is in the Advanced Setup section of this guide.

Document Your System

The components in your system will determine the required settings. It is important to have the following information documented. Take time now to fill out this information, as it will required to properly configure your inverter and charger.

Personal Settings Record

A. Battery Type (Choose One): _____Wet Flooded _____AGM

B. Number of 12-volt battery banks: ______________
If individual batteries are 12-volt, enter the total number of batteries
If individual batteries are 6-volt, enter ½ the total number of batteries

Example: For a battery system comprised of 8 6-volt batteries, the value should be 4

C. Battery 20Ah Rate: _________

D. Inverter Model: ___________

E. Charger Model: ____________

F. Max Charger DC Output (See Table 1) ___________

G. Battery Bank Capacity: __________Ah
Multiply value in [B] above by the value for [C]

Table 1
The common chargers used by Newmar are listed below. If your is not listed, you need to find this value before continuing.

Model Max Output (Amps DC)
MS2000/12, MS2012 (-15/ -20B) 100
MS2812 125
MS2024 60

Magnum Settings

Common ME-RC settings

The common settings are found under the Setup menu.

01 – Search Watt: 5 Watts

02 – Low Battery Cut Out: 11.0

This value is one reason why you should install the ME-BMK, since the voltage is measured under load, and false low readings are common. With a ME-BMK installed, this value can be set to a more reasonable 10.7 or lower.

03 – Absorb Time:  _______________

Magnum provides a chart for determining the best time, based on amp hours of the battery group. To keep it simple, compare your value in [G] to the values below

200-300Ah – 60 Minutes
310-500Ah – 90 Minutes
510-700Ah – 120 Minutes
710-900Ah – 150 Minutes

04 – Battery Type: _____Flooded   ____AGM2    ____AGM1 (Non-Newmar provided)

Newmar coaches will have either Flooded or AGM2.  Look at your value in [A] and choose the correct option above. All Newmar AGM batteries are made by Discover, even though they may have a different label. Discover batteries are type AGM2. If you replace these with Lifeline AGM batteries, that would be AGM1.

05 – Charge Rate: ________ (see instructions that follow to compute this value)

AGM batteries typically can be charged at 100% rate, while flooded need to be set to a value based on a formula. The formula is C/BMr, where C = the total amp-hour capacity of the battery bank and BMr=Battery manufacturer rate.  Follow the steps below to compute the proper value for charge rate.

C: __________ Total Amp Hours
                Enter your personal settings value [G] above

BMr: __________

Compare the value you documented in your personal settings [A].

For Flooded a value of 10-20 should be chosen. Interstate GC2-HD batteries have a charging current of C/10, so you would enter 10 for the BMr. If you do not know the value, then a conservative number of 20 should be chosen.

AGM batteries from Discover are a value of 5.

Max Charge Rate (C/BMr): ______
Divide the value in C by BMr
Example: If your battery bank is 840Ah with AGM batteries, then Max Rate is 168amps

Personal Settings –Max Charger DC Output [F]:  ______

Final Charge Rate %: _______ (Use this value for 05-Charge Rate above)

Instructions: Divide the Max Charge Rate by the value for your personal settings [F]. This will give you the proper charge rate. If the value is > 1, then 100% should be set. Otherwise set the percentage that is closest to your number without exceeding

Example: Your charger has a Max Charger DC Output [F] value of 125amps. Your battery bank is 200Ah flooded (C), with a BMr value of 10. 200/10 = 20amps. 20/125 = .16 or 16%.  05-Charge rate should be set to 16%

06 – VAC Dropout: 90 – 100 VAC

This setting is the minimum AC voltage that must be present on the INPUT side of the inverter before the Inverter will switch to standby mode. The default setting of 80 is too low for the residential refrigerator and many electronics. This value could be set even higher, such as 100VAC safely. It really depends on the quality of the electricity where you are camping, and how often you want the inverter to take over.

09 – Final Charge: ________ (see instructions that follow to compute this value)

If your value in [A] is Wet flooded, then you need to use the “MULTI” mode. This will prevent the batteries from over charging and reduce water consumption. The batteries will charge to a full charge and then stop charging until the battery voltage drops below 12.7V, then it will restart charging. The display will read “Full Charge” once it has entered the waiting state.

If your value in [A] is AGM, then the proper value would be Float. This will keep the batteries at a full state of charge.

Common Usage Scenarios

For normal operation, the charger and inverter should both remain turned on. This will allow the charger to maintain the battery bank anytime AC power is available, either from the generator or shore cord. When AC power is not available, the inverter will supply AC power to the residential fridge and other power sources by drawing DC power from the battery bank.

The inverter will consume a small amount of power even without a load. For this reason, if the coach is to be stored without electrical hookup, the inverter should be powered off by pressing the power button on the remote control labeled “inverter”.  When the inverter is disabled, the residential fridge will not be powered.

Hot Weather with 30-amp shore power

Connecting to 30-amp power can be problematic without proper planning. Newer coaches will have an automated energy management system (ems) that makes the experience much more enjoyable. The ems will borrow power from the inverter to help with burst energy, will automatically lower the charger rate, and will disable power to high load devices to prevent breakers from tripping.

Without an ems, the charger can be manually disabled or lowered. Disabling is not a long-term solution, as the 12-volt system will still be used for lighting and many other accessories, and the batteries will eventually drain. Disabling the charger for a few hours is generally safe.

Driving without Generator

When driving, the alternator will provide a charge to the coach batteries. This is generally enough to keep the batteries full while using the inverter to power the refrigerator, televisions, and even the microwave.

Auto Generator Start

While the inverter can supply some household devices the 120VAC, it does not have the ability power all the air conditioners. With the integrated Auto Generator start (AGS), the magnum inverter can start the generator based on a request from the air conditioner thermostat.

The AGS can also be used to trigger a charge on the batteries, starting the generator when the batteries reach a defined low point, and running until the batteries reach a defined high point.

AGS Setup options

AGS: 03 Run Time Hour: ________
                Recommended setting to match the value configured for 03-Absorb Time

AGS: 04 Start Temp F: Ext Input Setting this to Ext Input will trigger the AGS when the thermostat calls for A/C cooling or heating. Most Newmar after 2014 can use this Ext Input.

AGS: 05 Start Volts: 11.0 VDC

This setting will trigger the generator based on voltage. See the discussion for “02 – Low Battery Cut Out”, as these values are related. The use of a BMK is much more reliable here too.

AGS: 07 Quiet Time Menu: _______

Choose the appropriate value for quiet time. When a time range is selected, the generator will not auto start.

Enable Auto Generator Start

The settings for AGS determine what will trigger the AGS when the AGS is engaged to the auto mode. Press the “AGS” button on the controller and rotate the select knob to choose between OFF, Enable, Enable /w Quiet Time, Test.  When you have enabled the AGS menu, the generator will be triggered by the settings under “04 Start Temp” and “05 Start Volts”.

Advanced Setup


The Magnum ME-BMK is a single battery bank amp-hour meter that functions like a gas gauge for your battery bank, giving the exact state of charged expressed as a percentage value of 0-100%.

Newmar does not include the ME-BMK on any of their coaches and will not allow it as a special. Installation involves adding 2 additional 2/0 battery cables from the ground to the shunt. Typically, a length of 4ft is long enough for these additional cables. All original ground cables need to be moved from the battery to the opposite end of the BMK shunt. See Figure 7 demonstrating the wiring differences.

Although the ME-BMK will work with the standard ME-RC remote control, the support is limited as is the functionality. In order to utilize all the features, the remote must be replaced with the ME-ARC. This is a direct pluggable swap.


The Magnum ME-ARC is a direct replacement to the standard ME-RC that offers many advanced configuration options. The primary reason to choose this remote control is to fully utilize the ME-BMK and to properly maintain the batteries. This section covers the settings specific to use with the ME-BMK and assumes the ME-BMK is already installed.

Common ME-ARC + ME-BMK settings

Only the common settings are covered in this guide. Many of the settings will refer to your specific system settings that you documented earlier (A-G).

To enter the settings mode on the ME-ARC, start by pressing the button labeled “SETUP”, and rotate to find the sections 01 thru 06. To enter the desired section, press the dial in, and then continue to rotate thru the options under the section.

01D Max Charge Amps:  _______________
Instructions: Follow the steps under Common ME-RC Settings 05-Charge Rate.  Compute the Max Charge Rate (C/BMr) and use that value. This entry for ME-ARC expresses the rate in amps, so there is no need to compute the Final charge rate % here, but you will need it for 03E Max Rate Charge below.

02B LBCO Setting: 10.7
Instructions: This is a safety value in case the SOC meter for some reason has not been calibrated properly. The lowest acceptable value for a battery bank under load is 10.5-volts DC. If you are wanting to stretch the battery bank as far as possible, you can safely lower this to 10.5 and adjust the SOC to 20%

02E AC In – SOC: 80%
Instructions: This value is highly personal choice. It should never be lower than 20%. I keep mine set to 80% by default and adjust it lower if I am boon docking. Setting this to a lower value to use more of the battery capacity is safe, as long as it is not set below 20%. Read the note for 02B LBCO for the matching adjustment.

02F Power Up Always: On

03A AC Input Amps: 30

03B VAC Dropout: 90-100VAC

03C Battery Type: _____Flooded              ____AGM2         ____AGM1 (Non-Newmar provided)

Newmar coaches will have either Flooded or AGM2.  Look at your value in [A] and choose the correct option above. All Newmar AGM batteries are made by Discover, even though they may have a different label. Discover batteries are type AGM2. If you replace these with Lifeline AGM batteries the setting previously was AGM1 but unfortunately Magnum has not kept up with the changes at Lifeline. For Lifeline AGM batteries under the setting “Battery Type” use “Custom” and enter the following values. Absorb=14.3v, Float=13.3v, and Equalize=15.5v. The Custom setting also works for other battery types that do not fit the standard charge profiles of Flooded, AGM1 or AGM2.

03D Absorb Done: SOC

03E Max Charge Rate: ___________
Instructions: Follow the steps under Common ME-RC Settings 05-Charge Rate.  Compute the Final Charge Rate % and use that value.

03F Max Charge Time: 18 Hrs

03G Final Charge Stage: ________
Instructions: If your value in [A] is Wet flooded, then you need to use the “MULTI” mode. This will prevent the batteries from over charging and reduce water consumption. The batteries will charge to a full charge and then stop charging until the battery voltage drops below 12.7V, then it will restart charging. The display will read “Full Charge” once it has entered the waiting state.

If your value in [A] is AGM, then the proper value would be Float. This will keep the batteries at a full state of charge.

04A Gen Run VDC:  Start Volt: OFF / Stop Volt: OFF
Instructions: The voltage will not be used for AGS since a better option exists with the ME-BMK

04D Gen Run SOC:  

Start Gen SOC: 60% is a good balance battery usage/minimal gen run time. Increase up to 80% for max battery cyclic lifetime. Decrease as low as 50% for max battery usage.

Stop Gen SOC: 90% is a good set point to minimize generator run time. Setting it to 95% will add about 30 minutes gen run time and setting to 100% will add 1 hour of additional run time.

04E Gen Run Temp:  Set Gen Run Temp Start: Ext Input
Instructions: The voltage will not be used for AGS since a better option exists with the ME-BMK

05A Charge Efficiency: Auto

05B Amp Hour Size: ___________
Instructions: The voltage will not be used for AGS since a better option exists with the ME-BMK


Revision 4: Release May 29, 2019

  • Clarified that multi-mode final charge will stop charging until the battery voltage is below 12.7v.
  • Corrected/Updated the information on Lifeline batteries and the proper custom settings.

Thanks to Don (757driver) for these corrections.

Revision 3: Release May 3, 2019

  • Clarified that AGM batteries have a slower self-discharge rate. Previous wording incorrectly stated they had a slower discharge rate.
  • Fixed Figure 6 image of factory wiring, it had a missing jumper wire in the image
  • Clarified the maximum safe discharge of a battery bank
  • Added additional instructions for utilizing the ME-BMK and ME-ARC to maximize battery consumption for maximum boon docking per charge.

Revision 2: Release May 2, 2019

  • Minor typographical errors corrected.
  • The formula for Battery bank capacity under “Personal Settings Record” was corrected
  • Additional details where added for “Why you need a current-based estimation system”

Revision 1: Released May 1, 2019 – Initial release

Sanicon hose wetbay exit cover

I purchased my 2019 Newmar Dutch Star without the factory option for the sanicon. The primary reason I did not have the factory install it is their setup was not ideal, and I wanted a better solution.

One of the features that Newmar includes is a solid nylon disk that is pre-fit to the hose. This disk will block the 5 inch exit hole while the system is connected to sewer. Utilizing the factory exit hole allows for the bay door to be securely closed. With the Newmar provided disc, this hole is sealed.

I attempted to purchase the disc directly from Newmar, but after several months of unsuccessfully trying to even get a part number, I gave up.

I recently acquired a 3D printer, and my first design and print was cover that can be used to fill the hole.

I wanted the cover to be easily installed and removed, so I designed a slot that allows the hose to be inserted. Once the hose is installed, a small end cap is inserted that secures the openings, preventing rodents and other bugs from gaining access.

Here is some pictures that show what I came up with.

Girard Nova Awning Protection Switch

There have been numerous reports of the Girard Nova Awnings deploying on their own. I have never experienced this in the limited time I have owned my 2019 Newmar Dutch Star, but I did receive a call from Newmar specifically advising me to leave the awnings unplugged unless I intend to use them.

The location of the plug is in the bays, and although not hard to access, it is an extra unnecessary step and an inconvenience to have to unplug each time.

The reasons for the deployment given where a possible grounding issue, which has yet to be identified. Since I park my RV in a garage, this could be a real problem if the awnings deployed.

The Girard Nova awning has a Emergency break cutout circuit, that is supposed to retract the slides once the break is released and then after 60 seconds will remove all power to awnings to ensure the awnings will not deploy. In spite of this circuit, numerous claims of awning deployments while driving have been made online, and Newmar has confirmed several warranty repairs for this exact problem. I do not have data as to what years are affected, nor how many models.

My goal is to make certain that the awnings cannot deploy, and since Newmar has stated the only way to do this is to remove power, I decided to go along with that plan, but in an easy fashion. What I have installed is a relay controlled power strip.

The plugs will only be turned on when my switch passes 12 volt DC power to the relay. This was accomplished with minimal effort and cost, and restores the luxury of using the awnings safely and conveniently. The switch is located on my left hand side console, in front of my transmission. Not an ideal place, but this was an unused switch for the tag dump, which was replaced with a function on my HWH Active Air. By using this location, I didn’t have to cut into the dashboard, or do extensive work. I will most likely relocate the window up/down button to this position once I receive the custom switch I have on order. For now, I am using the Tag Dump switch, rewired to only make use of the ON/OFF and not connecting to the momentary (ON).

The parts list for this project:

  1. Controllable Four Outlet Power Relay
  2. Custom Made wiring Harness
  3. Custom L-Series switch
  4. Power Distribution Box
  5. 16 Gauge Wire
  6. 12 Gauge Wire
  7. 10 Gauge Wire

For the custom wiring harness, all that is required is a single 16awg signal wire running to the switch. Since this is a long run going from the bays to the dashboard, I decided to make a custom wiring harness with extra wires for the future. I included 6 different colors of wires in a wire loom, and ran it inside the frame rails to the front of the RV. I then entered the wiring compartment below the drivers seat, and ran it up to the dashboard. This harness is now fully accessible for any future projects.

Making the harness was rather simple, but time consuming. My hands were rather sore after putting all that wire inside the loom. I ended up with a 30 foot harness, which can easily reach the cabinet above the driver, or the center console behind the screens. I also left a pull string in the chase for future wire installation. After taking the time to fish the first wire, it is always wise to leave a pull string behind.

Since I was already running wire from the 12v power bay to the dashboard, I made a secondary harness with 3 10 awg wires (Red/Black/White) and connected to the KIB terminals. These terminate behind my dash into two distribution boxes, one for ignition power, and one for constant power. I will use this to tap in for my Dash Camera, Tablet Power, and other accessory power items in the future.

With the power distribution in place, the switch needs to have a 12v power supplied to one leg, and the positive signal wire connected to the other, so that when the switch is ON, 12v DC power is supplied to the signal wire. I used a common ground for the Negative side of the signal wire. The finished product allows me to now safely cut the power to the Girard awnings with a simple toggle switch, and I no longer have to disconnect and reconnect the power cords.

Girard Awning power connected to switched outlets.


I originally used the tag dump switch, but have since replaced that switch with a custom switch. This is illuminated when it has power, so it is easy to see that it is energized.

Newmar Engine Preheat installation

ITRTouch Remote

The ITR Heat Oasis CH50 is a diesel hydronic heating system that is pre-installed in the 2019 Dutch Star. This provides for domestic hot water, and furnace heating for the whole RV and basement. The oasis is powered by either the diesel burner, or by electrical providing either 5k or 10k BTU. Engine waste heat is also used to provide heat energy to the distribution module, allowing for all system functions while driving without the use of additional heat sources. 

All units are pre-wired for the engine loop pump. The panel will have to be replaced with one that provides the Engine Preheat Pump switch, and the pump will have to be installed inline.

I opted to go with the ITRTouch Remote because I liked the look and it provided the function for preheat. When replacing an existing switch, you will need to order the over sized ITRTouch remote to cover the hole used by the original, which is taller and slightly more narrow than the new one. You can use the new ITRTouch without the pre-heat option. If you want to play with a demo of this switch, ITR has one on their website located here.

The new remote is 1/4″ wider than the standard switch. Once the hole is the proper size, the wiring harness will connect to this switch as a direct replacement.  The pump was $295, and the new remote was $260.00 before any applicable discounts.

To perform the installation of the pump, you will need several items:

  • 4 inches of 3/4″ ID heater hose
  • Qty. 2 – 3/4″ hose clamps
  • Qty. 2 – Hose pinch off pliers
  • A dozen or so absorbent shop towels
  • Qty 1 each – 16 gauge Fully insulated spade Connector Male/Female

When I started the install, I only had 2 sets of hose pinch pliers, and they were too bulky to properly close the hose in the cramped area. I ended up spilling about 2-3 cups of fluid before I gave up and reconnected the hose. I then researched what I could get delivered in 1 day from Amazon, and found these clamp pliers. What I liked about this style is that they are not vice-grip style, using a ratchet style system instead. 

DM12 Distribution

ITR Oasis DM12 Distribution Module

Newmar places the DM12 distribution panel behind a wall in the bay just behind the pass thru bay. Removing the wall will expose the DM12, and provide you with access to perform the full installation.  Looking at the graphic for the DM12, you will see that the left side is where the engine coolant inlet and outlets are located. The pre-heat pump is installed on the outlet side, with the pump oriented to return the coolant to the engine.

Place 1 clamp on the inlet side, about 3 inches above the clamp, and another on the outlet side, about 6 inches from the clamp. I used a 3rd clamp and clamped the line higher up at the frame rails. This allowed me to capture the fluid in the line in a controlled manner, and have more flexibility with working with the hose.

Once the outlet is disconnected, place the pump in the final position and connect the engine side to the pump. There is not enough room to connect the pump and then re-position it to the back wall. The other hoses will not allow for the pump to fit through. Also pay close attention to the routing of the return hose, ensuring that it will not rub or kink. I had to alter how it routed from the frame rail down to get a proper alignment. I personally did not have the proper tools for easily handling the continuous pressure clamp, so I removed this and replaced with a worm-gear hose clamp.

Install the 4″ of 3/4″ heater hose to the outlet side of the DM12 and connect to the pump.

Secure the pump to the back wall, but use caution on the screws length,as the other side is where all of the 12v electrical connections are located. 

The electrical needs to be connected to the pump using the spade connectors. The wires are red and black, and are exiting the DM12 above the outlet connector. They will be crimped together for protection. When doing the final routing of the electrical, make sure it does not rest along the heater.

After cleanup of any spilled fluids, place clean white towels around all connections that have been replaced, and run the engine for 30 seconds. Verify that your towels remain clean white, and that there is no leak. 

Next, bring the ITR up to running temp and turn on the pre-heat option. Verify the pump is operating.

Since I had spilled so much fluid, I was worried about the air in the lines, and the loss of fluid. I ran the pre-heat pump for several hours, which was overkill, and then topped off the reservoir with coolant.

The final step was to take a test drive and bring the engine up to operational temps and let it remain for 30 minutes. This was about an hour total of driving. After that, I was satisfied that there would be no leaks, and closed it up.

For a view of the Remote Control operation of the Oasis, view this video.

For a view of the final pump installation and commentary, view this video.


Installing a Battery Monitor Kit (BMK)

Thought I would put some more of my modifications up. I have been working on installing the ME-BMK in my coach. If you are not familiar, this is a Battery monitor kit that acts like a fuel gauge for the battery bank. It is a far more reliable way to determine state of charge (SOC).

You can read about it here: ME-BMK Battery Monitor Kit

I attempted to get Newmar to install this as a special, and was told no. Well it turns out that there is good reason for it, and the upgrade is very involved with the 2013 Newmar coaches.

The typical installation of a BMK is to install the battery shunt between the load and battery ground, install the ME-BMK-NS device. Provide 12v power to BMK-NS, connect the network to the inverter, and install a sense cable between the BMK-NS and the shunt.

The 2013 Newmar coaches come with the Magnum ME2812 inverter, the ME-AGS-N (auto genstart network version) and the RC-50 remote.

For the features of the BMK, you need the ARC-50.

This is the easiest part to swap out, remove 4 screws, unplug RC-50, Plug in ARC50 and install 4 screws. At this point you must reprogram all of your settings. Do this now, as it will not be setup for your battery type.

After installing the ARC50, then I installed the shunt. There are 2 ground bundles connected to the coach. Mine is the all electric, with factory AGM batteries. So I have 8 6v Batteries. From the factory there was a main 0-gauge ground going to the inverter, and then a bundle of about 8 smaller wires going to the main electric panel. These were connected at different points on the battery. For the BMK to do its job properly you need to move all ground wires leaving the battery to the load side of the shunt.

In the above picture you will see the shunt installed below the two positive wires. The back side is the load side, and the original wiring from Newmar is attached there. You will see two cables coming off the stud. I had to cut a lot of straps, and then reconfigure the straps so there was no metal rub and the tray could still slide. This wasn’t hard, but took some thought.

The front side of the shunt is where the battery connects. I made a custom 4/0 gauge wire, and soldered the ends instead of crimping. Lots of solder..and then shrink wrap the ends to make it look neat.

The above picture shows the battery tray extended, and the bottom right ground is my cable connecting the battery to the shunt. Just to the left is the temp sensor for the inverter, this came stock.

The BMK-NS module is installed in the bay closest to the battery, as the sense cable can not be cut or spliced. 

On the back wall is the black box with the power connection, data cable, and sense cable. 

So after getting it all hooked up, I tested and things worked great. my SOC read accurate, I was able to drain it down to 80% and have it shutdown the inverter. Plug in power, and it charges back to 100%. 

So then I decided to test AGS. I set the AGS to start at 80% and stop at 90%. Watched it drain down (helped with microwave) and once it hit 80% the generator fired off. After the 60 sec warm up it stopped. Then started again, and this loop kept going.

Frustrated – I double checked everything. In the mean time I had to stop my work, and take the coach to the dealer to get some work done. That was hard..I hate leaving work undone.

When I finally got the coach back I started playing with the settings and discovered that if the ME-BMK-NS is plugged in (either power or network) then the AGS will not function. Even turning it to manual run via the ARC50, it will do the cycle. I could start the generator with the dash switch, my software switch, or from the generator itself, but not from the ARC50.

If I unplug the ME-BMK-NS then it works from the ARC50, but of course now I can’t use SOC to start.

I placed a call to tech support at Magnum Energy, and after 50 minutes of diagnosis the culprit was found. 

The 2013 Newmar coaches include a Power Control Systems EMS. The inverter actually connects into the Power Control module, and then the remote connects to another port on the Power control module.

Here is the diagram and install docs:…structions.pdf

In the mid toilet room, there is a cabinet with all the breakers. This box houses the PCS control. 

This picture shows the box removed. Lighting was poor because I had no 12V or 120V…that would have been dangerous.

3 telephone connections are behind. I had to locate the one with black tape (matches cable connected to magnum inverter remote port) and the one with blue tape labeled “remote”, which matches the cable going into the ARC-50.

Once these were located, I unplugged, and connected them together with a telephone joiner.

As soon as that was complete, and I fired it all up, things worked as I expected.

So my next step was to contact Precision Circuits and find out what I could do to make the BMK compatible, and what I was losing by doing the bypass.

I sent an email, and the response was very fast and informative.

Here is the response:

By bypassing the PCS system will cause you to lose two things.
If you normally plug into 50A service, then this should not be a problem. If you regularly plug into 30A service, then you may want to consider updated the system.

What you lose when PCS is not communicating:
If RV is drawing more current than the Main Circuit Breaker can supply, then PCS first attempts
1. Battery Charge Reduction, (temporarily reducing Battery Charging rather than shedding a load)
2. Inverter Assist, (temporarily allowing Inverter to produce 120V power to run the appliances that are wired to it, like the Microwave)

PCS will continue to operate, and will shed the Appliances, and continue to prevent circuit breaker tripping.

Most people choose to bypass

If you choose to upgrade, you would have to send in the PCS Monitor and PCS Control. We would be willing to upgrade free of charge, and could ship back to you within 24 hours of receipt. 

Just emailed with Magnum, and they state the ME-ARC50 already has the upgrade,

The PCS Control is inside the Circuit Breaker Panel.
It is the Control where you plug in the Magnum Remote and Magnum Inverter data cables.
About 1 to 2 hour job to replace if you have never done one.

PCS Monitor is the Central Monitor Panel

PCS also sent me an upgrade document that outlines the complete install steps, and also gives info on what is gained. The biggest gain I can see is the communications is no longer done ‘man in the middle’, but rather part of the RS-485 bus. So instead of being a relay, it now assigns itself an ID on the network, and takes action that way.

There are a few new features, including the ability to set to 15amp service (30->20->15->30) and the removal of the blinking panel LED light. 

Taken from document:

Additional PCS Features included in new Version:
1. PCS Central Monitor Panel
a. Displays error message during loss of communications with PCS Control rather
than appearing to be running.
b. Displays message when PCS Control is busy communicating with Windows
WinPCS program. (Requires Power Cycle to reset.)
c. When No Service present, does not keep bouncing or forcing back to this
screen; allows troubleshooting of other conditions.
d. Unplugging and re-plugging Monitor during error condition does not mask the
error. (Error message regenerates.)
e. Installation without Magnum Inverter-Assist feature now displays correctly.
2. RV Data Mismatch error will no longer lock up system, but PCS will continue to
retry in cases of poor connections or low battery.
a. During an RV Data Mismatch, Control will continue to operate with RV Data it
has stored, rather than stopping all operation.
b. This error condition will no longer stop Magnum Remote/Inverter
3. Force RV Data from Remote to Control.
a. If Control has been mis-programmed at the factory with the wrong RV Data it no
longer needs to be replaced. Only a new Monitor needs to be shipped to Dealer
to reprogram system.
4. Clearing RV Data in Monitor to restore to Blank condition.
a. Monitor can be restore to original Blank condition, without the need for Windows
software, or the need to send back to Precision Circuits.
6. PCS Control slows down the Load to Load turn on delay.
a. When turning back on loads, wait 5 seconds from one to another load, to assist
Generator recovery when heavy loads are turned on.
7. Add one more Service Type 15amps
a. Now It will step 30amps -> 20amps -> 15amps ->30 amps
8. Remove Central Monitor Panel blinking LED
a. Customers complaining during night
9. Delay Generator Run Signal, so that if Generator is wired to Engine battery, starting
RV engine will not cause PCS to lose Gen Run signal.
10.Turning Inverter Off at Magnum Remote, still allows manual override of Inverter-
Assist Feature, and Battery Charge Reduction Feature.
11.Allowing Inverter-Assist when in Absorb Charge Mode. Previously Inverter-Assist
would only operate in Float Charge Mode. Note: If Low Battery Cut Out threshold
reached, then Float Charge Mode is required.
After I received my upgraded PCS unit, I was able to reinstall it without any trouble. The upgrade fixed the problem I was having with the BMK interfering with the AGS. 

I spoke with the owner of Precision Circuits, and he explained that the big difference in pre-upgrade vs post-upgrade is how communication works. The way the unit is shipped from Newmar, the PCS controller talks to the Magnum Inverter, and the remote talks to the PCS unit. The PCS is doing a ‘relay’ of all messages between the two. Works fine, until you do something silly like upgrade or add a component after market. Then it all falls apart because there is too much communication going on.

Post-Upgrade, the PCS is just another device on the bus, and is able to listen to what is going on, and then send requests. 

So now when you are on 20 amp service and want to run the microwave, and you are 10 amps short, the pcs will call to the inverter to ‘assist’ as well as override the command from the remote for charger, either doing a setback or shutdown temporarily.

PCS is going to be delivering the new units to all manufactures with this upgrade within the next few months. So earliest you would see this factory installed is mid model year 2014, but most likely it will be a 2015 option.

If you want it now, it only took me 30 minutes to remove and another 30 to reinstall. Shipping cost me $25, and the upgrade was free from PCS.

Overall, this was a bigger project than I expected, but one that I am very pleased with. I firmly believe that every coach should have a BMK, no matter how little you use the battery. This is the only true way to protect your batteries.
***UPDATE 2018-July-04****
I have been using this system for over 5 years now. The original batteries are installed, and they are still working! I keep my coach plugged in all the time when storing, and have kept the SOC set to 70% max usage for my normal habits.
Over the past 5 years, I have manually set it to 50% for the few times that I was boon docking, and dealing with Generator restrictions (ie: National parks). The battery life is absolutely amazing. There is now way these would have lasted as long if I had not installed the BMK.