Tuesday, March 21, 2023


What size BatteryMINDer do I need for my Class A?

Dear Dave,
You suggested buying a BatteryMINDer in a recent newsletter. Prices for a BatteryMINDer on Amazon range from $59 to $189. Which one should I buy, and how and where do I install it? Or is it only used inside the engine when parked and then removed? —Millicent, 1996 Fleetwood Bounder, Class A motorhome

Dear Millicent,
There are several different sizes of the BatteryMINDer®, starting with the small, single battery maintainer that I usually find on Northern Tool for $39.95. I have also found it on sale for $19.95 and bought six of them for backup units when we do shoots and have units sitting around for several weeks.

Different models of BatteryMINDer

This model only has a 1-amp charge and does not have several of the features of the more expensive model 1500, but it is a great cheap charger that does desulfation.

The model 1500 provides 1.5-amp charging, desulfation, and has reverse polarity protection as well as temperature sensitivity. It runs $59.99 and will charge two batteries, but it does take longer.

If you have two or more house batteries, then I would suggest upgrading to the larger 2-amp charger that will cost somewhere over $105 but will provide much more charging efficiency.

The difference in cost depends on the charging amps and the type of battery. There is a more expensive model that has a 2/4/8 amp charge with temperature control, overcharge protection, and other features. They even have a charger now for lithium batteries.

Four 6-volt lead acid batteries

Your 1996 Bounder most likely came standard with four, 6-volt lead acid Trojan batteries connected in series (positive to negative). Those provided two 12-volt “banks” that were then connected parallel (positive to positive, negative to negative). They were charged with a traditional converter that just did 13.6 volts until the batteries were at 12.6 volts. They then dropped to a maintenance charge of 13.2 volts. This charging procedure does not break up sulfur that forms on the plates, so the BatteryMINDer can be used to supplement that charger and prolong the life.

If you have the four 6-volt batteries, I would recommend the basic 2-amp charger to help properly charge the house batteries just during storage. Let the onboard converter do the main charging when you are using the system. This should cost about $80 at Northern Tool. That is, IF you have 120-volt power to plug into when the unit is not being used. If not, they offer a solar panel version that can be purchased with a 30-watt panel. You will, however, need to be exposed to sunlight for this option to work.

I would recommend giving BatteryMINDer a call and talking with their technicians about the type of battery or batteries you have and the best option for you. You will find the products on their site are more expensive than Northern Tool, as they stated to me that they don’t want to be in the retail market so they recommend buying from Northern Tool.

And just to clarify your last point, this product can be used on the deep cycle house batteries, which is what my original article pertained to, or can be used for the cold cranking amp (CCA) engine battery. The engine battery would be just a quick plug in during storage and then removed. You should be able to just purchase the smaller 1500 model.

 You might also enjoy this from Dave 

RV is plugged into 30 amp in a heated garage but engine batteries still die. Why?

Dear Dave,
My RV is plugged into a 30 amp that is located in a heated garage. Today and earlier this year the starter batteries were dead. I left the bay lights on for about 24 hours. I boosted the batteries with the house batteries, started the engine, and then shut the engine down. Then I connected a battery minder to the two starter batteries. After a couple of hours, the red light went out on the minder or tender. I was surprised that it went out so soon. —Denny, 2011 Monaco Camelot 43DFT

Read Dave’s answer.

Dave Solberg is a leading expert in the RV industry and the author of the “RV Handbook.”

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Thomas D
1 month ago

I use a dura cell branded maintainer . It is 800ma or 8 tenths amp on my dura max with 2 600+ cca agm batteries. So far after 3years batteries are just fine.
( truck in storage in winter)

David N
1 month ago

I use a Battery tender from Harbor Freight. Cost is around $12 each hooked up to the 12v starter batteries.
The shore hookup keeps the house batteries charged, when boondocking we have solar to charge them.
Ensure your house batteries are full of distilled water though.
I have used the Tender for 3 yrs on the 12v ( no problems)

Thomas D
1 month ago
Reply to  David N

The el cheapo at $4.99 ( on sale) is nothing more than a transformer and a single diode and a red pilot light. Nothing wrong with it because its so small in amperage but it offers nothing in voltage or current control.

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