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(Photo courtesy of Interstate Batteries)
(Photo courtesy of Interstate Batteries)

Mark My Words: Should you check deep-cycle batteries?

Editor’s note: This information is provided by the Escapees Club.

Q. My RV trailer came with maintenance-free, deep-cycle Battery Pro batteries and a solar panel that charges them when they get low. Can the electrolyte level in the maintenance-free batteries still be checked, or does it even need to be checked? — Loren

A. Most maintenance-free batteries are not truly sealed, and if the caps can be removed, distilled water can be added if needed. You’ll have to look at the tops of your batteries and see if they have any removable caps. If they are truly sealed batteries, then water cannot be added.

The only sealed deep-cycle batteries that do well in RVs are the absorbed glass mat (AGM) batteries available from solar equipment suppliers. These batteries are truly 100-percent sealed and are very tolerant to the kinds of use and abuse that are typical in an RV.

They’re quite expensive, but are perfect for installations where venting of gases or access to the batteries for adding water are problematic.

If your batteries are AGMs, then there is no maintenance needed other than occasional cleaning and tightening of connections. There are some good descriptions of the various types of batteries on my 12-volt webpages. Check it out at

About Mark Nemeth

In 1997, Mark quit his aerospace engineering job and became a full-time RVer. For almost five years he traveled the country while maintaining his website, Mark’s Fulltime RV Adventure ( posting monthly travel logs. Mark now travels part-time and works as the RV Safety Education Director for Escapees RV Club providing technical training at Escapees Boot Camp seminars, as well as assisting in many other areas of the club. He is also technical advisor for Escapees magazine. Learn more about Escapees RV Club at

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