Saturday, September 30, 2023


Extend your batteries’ life with proper care

By Greg Illes
Battery capacity is a common topic among RVers, with much discussion of LED lighting and various power-saving techniques.

But less understood is the specter of battery life itself. Batteries “die,” which typically means they won’t hold a charge or deliver rated capacity. When this happens, the debit card comes out and the price tag can be startling. Even a modest two-battery complement is $400 or more. If you’re an AGM (absorbent glass mat) advocate (and there are good reasons to be so), then up that price 50 percent. High-capacity setups are high-priced setups.

Some folks get good service from their batteries — five years or more. Others seem to be unlucky and find replacement necessary in as few as three years. In fact, battery life is not about luck — there’s a lot that you can do to extend the useful life of your coach batteries, perhaps by two or three times. Several influential factors are under your direct control.

Water level
For flooded-cell batteries, always keep the water at the proper level. Poor water maintenance is one of the biggest killers. (Sealed AGM batteries don’t have this issue, and don’t have corrosion issues to deal with — but are much more expensive.)

Discharge level
Battery life varies by a factor of ten with discharge level — fully discharging a battery creates the shortest lifespan. Don’t discharge your batteries below 50 percent of capacity. By far the best way to measure this is to check battery voltage under a light load. The 50 percent level is 12.0V-12.2V for most batteries (but check your manufacturer’s specifications). Sadly, stock battery-condition instrumentation in many coaches is very inaccurate. Use a good voltmeter or install a built-in meter.

Storage conditions
Partially discharged batteries have a much higher tendency to sulfate and degrade. Keep your batteries fully charged when stored or parked. Remember that even a disconnected battery has a self-discharge rate and needs charging even when not used. Use a trickle charger, or a three-stage charger to prevent overcharging damage due to heat and water loss.

All batteries eventually experience sulfation. This is where normal-operation sulfates become crystalline and cannot be reabsorbed. A desulfator can help break these sulfates down and restore battery health. These affordable units also maintain charge, and can be hooked up during storage.

It takes some diligence, but you can easily double your effective battery life with the proper attention and care.

Greg Illes is a retired systems engineer who loves thinking up RV upgrades and modifications. When he’s not working on his motorhome, he’s traveling in it. You can follow his blog at



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chris p hemstead
3 years ago

checkbook? How old is this article?

RV Staff
3 years ago

Ummm, yeah. Thanks, Chris. I updated it. (But I still use a checkbook so that didn’t even register.) 😯 —Diane at

3 years ago

I just installed 2 new deep cell batteries and want to keep them healthy and last as long as possible. And I just purchased the 15W solar panel with built-in Battery Tender 3-step microcontroller that Mike Sokol recommended to keep batteries fully charged while in storage. Sounds like a better solution than running a 100′ extention cord to the MH.

Anyone else have experience with this solar panel?

chris p hemstead
3 years ago
Reply to  cee

15w is hardly anything. Not sure it will do much.

3 years ago

The jury is still out meaning I will give the solar panel time to prove it’s worth the $140 I paid for it. The panel arrived yesterday so my plan was to hook it up to my batteries today. I first checked the state of the batteries with a voltmeter so I had a starting point. After 6 hours my batteries went from 12.4 to 12.8. I don’t think I would travel with the panel; my intent is to keep the batteries topped off with solar in the winter when my MH is napping. We have lots of sunny days. I guess I won’t know if my investment is worth it until winter is here. Looking forward to not using the 100′ extension cord and charger… no outlet required with solar :))

Donald N Wright
3 years ago

How does weather temperatures affect battery life ? Here in Texas, 100 degree days are normal in the summer, and most RV trailers have their batteries exposed on the tongue of the trailer for safety and easyaccess.

chris p hemstead
3 years ago

Hot weather is not kind to acid tub batteries. Car batteries fail more rapidly in hotter climates.

Tommy Molnar
3 years ago

My first set of 6 volt Trojans lasted us nine years, But, I was SO frugal with our power (we’re boondockers) that my wife almost divorced me. I made some ‘adjustments’, and we’re still married. Ahem.

chris p hemstead
3 years ago
Reply to  Tommy Molnar

Yeah, it’s better to please your spouse (and yourself) than your batteries.

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