Saturday, December 3, 2022


RV Education 101: Maintain water level in RV lead acid battery


By Mark Polk

If you have lead acid RV batteries, you need to check the water (electrolyte) levels in the batteries periodically. Hot weather, over-charging and high usage can deplete the electrolyte levels in the battery cells.

Wearing gloves and eye protection, check the electrolyte level in each cell and add distilled water as needed. To add the proper amount of water, look closely in one of the battery cells and you will see plastic skirting extending down in the cell about one inch. This is the fill well, or vent well. You only fill a battery cell to 1/8 inch below the vent well in the cell. Over-filling battery cells can cause battery acid to overflow and cause corrosion.

Distilled water should only be added after the battery is fully charged, unless the water level is already below the plates. The plates need to be covered at all times.

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Mark Polk’s tech tips are posted every Saturday in the RV Travel Newsletter and every Wednesday on the RV Daily Tips Newsletter.


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Tommy Molnar
1 year ago

For over 20 years I was a*al about checking our batteries. Like before every trip, and during trips, and while the trailer was just sitting there. We got nine years out of one of the sets of 6-volters. But this year I moved up to Lithium-Ion batteries and all that fuss and muss is history. Plus, the batteries are now mounted in the pass-through storage area in the front of our travel trailer. Our trailer sits outside in sometimes below zero temps, but as long as I maintained the batteries and kept them charged, they were fine.

1 year ago

I recently installed a battery watering system on my two lead-acid batteries that allows me to fill each cell completely without removing the caps and stops adding water when all are full. There is a pop-up float that signals that the cell is full. Uses tubing to connect all the cells and then t’s to a quick connect to which you attach a tubing that has a one-way bulb and tube that goes into the distilled water source. $54 on Amazon and possibility to do many more multiples.

2 years ago

Seems there are now lead acid batteries that have sealed access to their cells. Are these recommended for RV use

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