RV Motorhome Batteries - Keep Your Battery in Good Condition
RV Battery Care and Maintenance
As a retired Engineer, I can hardly contain myself from dropping into technical jargon and start lecturing on the design of Batteries, and cells, and charging systems, etc.
But, that is not the purpose of this section, and you can Google all of that specific information to your wits end in a thousand places on the web. So I will try to provide some useful information on RV's and Campers and their Batteries and Systems.
Batteries for different Campers
Batteries and Types of Campers-
You should understand that almost all of your Class-A , Class-C , and in some cases Class-B RV’s, have utilized a dual 12-Volt DC power system for years.
One system, the Chassis system, is pretty much the same as a normal Automobile electrical system, but is often designed for higher currents (Loads), with a few exceptions.
The other system, the Coach system, generally provides the 12-Volt DC power for everything in the RV Coach.
Since Fifth Wheelers, Travel Trailers and even Pop-Ups are towed by another vehicle they can be considered to just have the "Coach" system.
Keep in mind that, especially with the newer models of these towed campers, they will often even have many of the same appliances as the larger RV's.
Batteries Utilized in Campers-
A Pop-Up Camper or Towed Full-Body Camper might have one or two standard 12-Volt, Deep Discharge batteries, and get re-charged when the camper is connected to the towing vehicle and it has it's towing vehicle's motor running, or often, they may require being charged separately, when they are discharged.
Older (and sometimes smaller) RV's might have a single Coach and a Chassis battery, and each being a 12-Volt battery.
The number and type of batteries in RV's have changed over the years to where it is pretty standard to have a "bank" of two 12-Volt Chassis batteries, and a "bank" of four 6-Volt Coach Batteries, wired in a 12-volt configuration.
The Coach DC electrical systems are 12-Volt systems, so the 6-Volt batteries are wired in series pairs to provide 12-Volts, but by using 6-Volt batteries you can get a higher load capacity than by using 12-Volts batteries in parallel.
The majority of the time, by the way, these 6-Volt batteries are the same as those used in Electric Golf Carts.
RV Battery Disconnect Switch
Electrical Battery Selector Switches-
Again, I am staying away from describing all of the different Electrical systems and accessories in RV’s and Campers today. But, I do want for you to know a set of simple facts.
Manufacturers found out years ago, that they had to put a selector switch (and often breakers and/or fuses) on the Battery wiring systems, for safety if nothing else.
It was quickly obvious to them that the potential current flow that had to be turned Off/On was so high (under some conditions) that it was safer to use a low current switch to control a higher current solenoid (or relay).
This is now pretty much the standard with all RV's.
First you will have a cabin ON/OFF switch for turning off 12Volts to MOST of the Cabin items that use this voltage. You should use this switch to turn Off this cabin power when you are leaving the RV for a day or two. This will reduce drain on your cabin batteries while you are away.
The Coach switch location varies, by vehicle design, but is usually near the Coach Entrance for owner convenience.
Often these switches have an Indicator light of some kind on them to indicate that they are ON.
Then, your RV/Camper will have a pair of Master Breaker Switches that engage and disengage the 2 sets of batteries from the Chassis and Coach electrical systems, and are supposed to be used for long term storage conditions.
These are for additional safety when you are maintaining your batteries, and to reduce current draw on your batteries when you put your RV in storage for a long period of time.
Dons Book for RV Owners
PREVENTIVE MAINTENANCE for Batteries
With, all of this, remember, your batteries require regular PREVENTIVE MAINTENANCE.
I, and many "Full-Timers" recommend that you perform the following PM, as a minimum, on a regular basis:
· INSPECT your Batteries and the whole battery compartment along with wiring that is visible. Remember your RV is bouncing over bumps, swaying around curves.
A good thorough visual inspection, before a trip, and after you set up at your campsite, can save you a lot of heartache later if you find such things as loose wires, frayed wires, a cracked battery case, spilled battery fluid, or battery acid build-up on your terminals.
· Before every trip, check all battery fluid levels and refill any cells that are low on fluid, as necessary, with Distilled Water only.
· Before every trip, check that all battery connectors are tight, and are clean of any oxidation residue.
· When storing your RV for an extended period of time, check the batteries at least once a month and run your generator until they are fully charged. See the Table below for relative battery capacity.
· Remember, these electrical systems, even with the switches turned off, will leach low currents and this will, over time, discharge your batteries.
· When camping at a campground for an extended period of time, check the batteries at least every 2-4 weeks, especially the fluid levels in the Coach batteries.
Remember, that these batteries are powering most of your lights and many appliance control systems, so even though you are plugged into 110-Volts AC at your site, they are constantly being re-charged and can lose fluids over time.
· Also, when camping for an extended period of time, start your Coach engine at least every 30-days, and run it for at least 30-minutes to keep every thing lubricated in the engine system, but also to re-charge your Chassis batteries.
NOTE: Once you have parked and set up your RV, turn the CHASSIS Battery Switch OFF (if you have one), and the Chassis batteries will have a better chance to remain fresh longer for starting your Engine when you are ready to leave your campsite.
Keep those Chassis batteries Fresh, because when both switches are on, and you are not connected to 110Volt AC power (you know Boondocking, Rough Camping, whatever you want to call it), your 12-Volt Accessories are pulling power from ALL of your batteries including the Chassis batteries.
It is very embarrassing to get ready to pull out at a campsite, and find you don’t have enough juice to turn your engine over, or even your generator.
As I have mentioned, most RV’s have room for 2 (or more) Coach batteries, and is wired for these to be 12-Volt and to operate in parallel, providing twice as much current capacity, as one. Some RV’s utilize four 6-Volt batteries, and when wired properly, these 4 will provide more current than 2-12-Volt batteries.
The considerate manufacturer has these Coach and Chassis batteries stored on a pull-out shelf for ease of service, and are located wherever your specific manufacturer decided was best, but usually near the Engine and generator, if for no other reason, than to minimize the length of the high current wires required.
Coleman 10W Solar Battery Trickle Charger
Typical RV Battery Voltage
I have to get a little technical on you though. Here is some good information on what Battery Voltages should be in Good and Bad, Loaded and Un-Loaded Batteries.
Your typical 12-Volt Battery, when fully charged, and with no load should read 12.6 VDC.
When you start your vehicle, the alternator will charge a battery, as controlled by it's Regulator circuit, starting at 13.2 to 14.4 VDC, depending on the amount of current the battery draws. It will drop to 12.6 VDC when fully charged.
The following Table shows what the Open-Circuit (again, No Load applied) Voltage will be under different static conditions, and the approximate estimated percentage of charge remaining on the battery:
RV and Auto Battery Voltage and Charge Levels
12 Volt Battery
6 Volt Battery
Multimeter for RV use
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Notes for the Reader
NOTE: After fully charging, wait at least 12-hours to check the actual open-load voltage. This will allow the plates of the battery to stabilize and will provide a more accurate reading.
NOTE: Almost all RV’s today, like automobiles, utilize numerous computers in their electrical systems, and it is not recommended to utilize Fast Charge Jumper Chargers or Booster Packs to start an RV or car quickly, as the higher voltages can cause damage.
If your batteries are maintained and used properly, you should never need a Jump, but if you do, it is recommended to utilize a Slow charger to avoid damage to the Batteries and the RV electronics.
RV battery Maintenance Tips
© 2010 Don Bobbitt