Dear Dave,
I store and use my RV in the winter, and live in the Phoenix area. I leave my trailer plugged in in my garage when I am not using it. In the summer, I store the trailer and use it in Colorado, where it rarely gets above 90°. I bought the used trailer two years ago at which time I bought a new AGM battery. After two years, the battery was shot.
In both garages it is plugged into a 15-amp, 120-V outlet. There is also a three-stage converter. I camp almost exclusively at full hookups. I’m very disappointed that I only got two years out of the battery, so I purchased a lead acid battery. I see nowhere to add distilled water and was told it was maintenance-free.
Is there such a thing as a maintenance-free lead acid battery? Do you have any idea why I only got two years out of my battery using it as I do? Can you suggest anything that would extend the life of the battery? —Jim, 2019 NuCamp 320
Dear Jim,
There are many variables that are part of this equation, such as what make and model was the original AGM battery and what make and model of converter/charger? Most trailers are delivered to the dealership without a battery. Then most dealers will put in a cheap version, as very few buyers pay attention to that unless they are avid boondockers.
RV AGM batteries
One of the misconceptions of Absorbed Glass Mat (AGM) batteries is that they do not sulfate. Although they are less prone to sulfation, if not charged properly, they will sulfate and not hold a charge within just a few years. Without being able to test your initial battery, we cannot tell if it was sulfated or developed a bad cell.
Over the years I have discussed batteries with some of the technicians at Winnebago Industries and why they chose to go with a NAPA-brand Flooded Lead Acid (FLA) deep cycle battery. One of my contacts indicated that some of the industry standard battery brands that were excellent had been bought out. He explained that new manufacturing used thinner, less expensive plates, and cheap solder points rather than welds.
NAPA batteries
Winnebago went with NAPA because of the quality of the interior components, service locations, and its track record for the past 20 years. Unfortunately, there’s quite a lot of “junk” out there with all the big box stores now selling marine/RV batteries for as low as $89.95. If they don’t do some research, most people will just buy on price. Check out my post on Interstate Batteries here.
Just a few years ago I noticed a motorhome in our subdivision parked in the back yard of a neighbor. There was a Jeep pulled up to it trying to jump start the rig. Check out the article here.
They were on a bike ride across Iowa and had purchased a new set of batteries to ensure they had full power for the trip, as it would be staying in friends’ yards every night. The batteries they bought were maintenance-free deep cycle, similar to what you described, from an auto parts store. These were supposed to be “dual purpose” with enough cold cranking amps (CCA) to be used as an engine battery, as well. Not the best battery for 12-volt house applications, and they did not last. They bought NAPA batteries at the local store and have been happy with them.
Next variable
The next variable is the converter or battery charger your rig has. You stated yours is a three-stage converter but did not provide the charge voltage for each stage. Most of those converters are set up for FLA batteries. There is a very high voltage initially, called a bulk charge, then an equalizing charge, and finally a float or maintenance charge. AGM batteries have a different charging profile. This may have been your problem, as most do not like the bulk charge—which could be as high as 16 volts! I doubt you still have the old AGM battery to verify the charge, which should have been on a label.
Maintenance-free FLA batteries
There is such a thing as maintenance-free FLA batteries. However, they are not the best design for the RV application if you do a little dry camping. If you leave the unit plugged in all the time, as you indicated, the converter will provide a constant 13.2 volts to the battery, and it should last a long time. Since your converter is a three-stage model, I do not know how the sealed battery will react with the initial bulk charge as it will boil the acid and cause gassing.
Use a portable battery charger
My advice would be to get a portable battery charger that can be set to the type of battery you have. The BatteryMINDer uses high-impact waves and has less gassing. Shut off your initial converter and just plug this in for battery conditioning. You might also want to look at a different battery that is designed for RV use and is not as “generic”.
You might also enjoy this from Dave
Everything you need to know about charging RV batteries
Hello Dave,
I have a question on battery charging. Originally my RV came with two 12-volt flooded lead acid batteries. About three years ago I switched them out to AGM batteries. Since I’ve purchased the rig (new), I’ve noticed when the batteries need charging, and I am plugged in or running the onboard generator, the charging voltage is 13.6/13.7 volts, whether the batteries are at 50% SOC [State of Charge], or 90% SOC. Even if the batteries are fully charged, they will still show a charge rate of 13.6/13.7 volts for 2-3 days before it drops to 13.2 volts. It stays at that charge rate for this 2-3 day period regardless of the actual SOC of the batteries before it drops down to 13.2 volts. …
Read the rest of Steve’s question and Dave’s answer.
You should enjoy these questions Dave answered
• Do ‘Tire Saver Ramps’ prolong the life of RV tires?
• Why did the lithium battery explode and flame up?
• Plugged RV’s 30-amp shoreline cord into 50-amp outlet; now RV won’t run
• How long will an RV 12-volt refrigerator run with two batteries?
• Can I tow a fifth wheel with a 1/2-ton pickup?
Dave Solberg is a leading expert in the RV industry and the author of the “RV Handbook.”
Read more from Dave here.
HAVE A QUESTION FOR DAVE?
Send your inquiries to him using the form below.
##RVDT2556
Thank you, Dave! Interesting to learn that AGM batteries can sulfate. We replaced the house batteries once in the six years that we had RV #1. I figured we just damaged the first set by running them too low before charging. Now, I see there could have been a different reason, or at least a complicit factor. Have a great week and sapfe travels! 🙂
Progressive Dynamics sells some of the best converters for RV’s in my book. Even if your old junk WFCO needs replacing, use a PD in place of it with the charge wizard and get better life from your batteries.
I bought 4 x Trojan AGM batteries four years ago. For a variety of reasons they did not last and I just replaced them with 2 x 280 ah LiTime lithium batteries.
Best decision ever!
Before anyone rushes out to buy NAPA branded batteries, read reviews from actual users. Many, many unhappy buyers of that brand as well. I replaced my Alliance (Freightliner’s Brand) dual starting batteries that had been in my DP for ten years with a pair of NAPA starting batteries. Just a little over two years and they need to be replaced. Going back to Alliance.
Thing is…almost all these batteries are made by a handful of big mfgs, like East Penn, and just have a branded label slapped on them. Like most things now…planned obsolesence. If it has a one year warranty, be glad to get two years of use.
I’ve bought Rv batts from Mills Fleet Farm for many years. I have no idea who makes them however, they do last. The first set of two deep cycle went 9 years in our lst motor home. The 2nd buy in my current MH – one overheated and boiled dry at about 5 years – so I replace both of them. Gas engine batts are either Delco or Exide and I have had great longevity with those as well. I do keep the MH plugged in, stored outside and also have a small Winnebago supplied solar collector on the roof and a small desulfator unit in the batt. bay.