How to Check Your RV Battery

It is important to "tune up" your recreational vehicle's battery at least once every year. You may also want to check the battery before going out on your latest adventure. This article will tell you how to check your RV battery.

Method 1

Method 1 of 3:

Using Your Monitor Panel

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1
Look at your dashboard monitor when your RV is not plugged into an electrical outlet.^{[1]XResearch source}
- If you attempt to check your battery this way while it is plugged in, you will get a false charged reading.
^{[2]XResearch source}

Method 2

Method 2 of 3:

Voltage Test

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Most commonly, you will have a 12-volt battery, but sometimes you can have a 6-volt battery.
Open the hood of the RV.^{[3]XResearch source}
Place the black lead on your battery's negative terminal.^{[4]XResearch source}
A 12-volt battery should read between 12.5 and 12.7 volts when it isn't being used. A 6-volt battery should read between 6.25 and 6.35 volts.^{[5]XResearch source}
Anything less than 12.5 or 6.35 volts indicates your battery needs to be charged or replaced (if its charge depletes quickly).^{[6]XResearch source}

Method 3

Method 3 of 3:

Specific Gravity

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Refer to your battery's instructions if you are unsure of the levels in your battery cells.^{[7]XResearch source}
Record the number for each cell.
6
Test all cells and then replace your vent covers. Your specific gravity reading for each cell should be between 1.235 and 1.277.
- If the readings of all the cells average below 1.277 you will need to charge your battery.
- If there is a difference of .050 or more between the highest cell reading and the lowest cell reading, your lowest cell is probably weak or dead and your battery may need to be replaced.

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Tips

If your battery has been recently charged or discharged, you need to wait at least 6 hours before using a voltmeter to test it.
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Some (larger) RVs have separate engine and coach batteries. Coach batteries may be single or multiple battery arrangements and they provide power to run the lights and other equipment in the non-engine and non-cockpit areas of the RV. Each battery needs to be serviced individually. Many RVs have an emergency engine start switch in the cockpit which provides a temporary connection of all the batteries in the vehicle in the event that the engine battery will not start the engine. Often, connecting the RV to 110v (shore) power charges the coach batteries, while the engine alternator charges the engine battery. Note that extended disuse of the vehicle can lead to discharge of any battery and extended 110v connection for the coach batteries (for several months at a time) could lead to an overcharge (or electrolyte loss) situation.
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If you need to add water to the electrolyte levels, you must charge the battery and wait 6 hours before using a hydrometer.
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Warnings

Never try to open a sealed battery. There is no way to add water to these batteries and attempting to do so can result in serious injury and destruction of the battery.
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Always wear protective clothing and eyewear when using a hydrometer. The water contains battery acid, which can burn skin and eyes.
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