Battery maintainer

Bob Bancroft · Feb 10, 2023

Is there guidance available to properly size a maintainer to the load? I assume maintaining two group 31 batteries should be different than maintaining a single, smaller battery? My only maintainer is 850 ma, which I have used on single, smaller batteries. I think there are maintainers rated at 3-6 amps?

Russ from MN · Feb 10, 2023

If the batteries are any good they shouldn't require a larger maintainer than what you have.

JoeM(GA) · Feb 10, 2023

my big trailer has two 31's for the winch and pump, it's been on a .75 NOCO maintainer for years, keeps everything happy with no problem

BarnyardEngineering · Feb 10, 2023

If there is such guidance, I haven't seen any.

Do these batteries have a draw on them or are they just sitting idle? When there is no draw and the batteries are in good shape, any maintainer will be able to keep them topped off.

You can't have "too much" if the charger is truly a maintainer. It will only charge the battery to full and then maintain it.

I started out with the cheap harbor freight maintainers that do like 1A, but then graduated to the Schumacher maintainers that have indicator lights on them, and can charge at 1.5A. I did not like that you could not tell if the cheap HF maintainers were doing anything. When I add on to my "fleet" these days I'm buying the Harbor Freight Viking 4A maintainers.

Mike M · Feb 10, 2023

I have a small charger,maintainer,disulfator made for Sears by who knows ? settings of 1.5 , 3 and 6 amps. It however does not seem to turn off on maintainer mode. I used to put it on my car when it sat in winter but it seemed to boil the water out of the battery. I always unplug it when it is done now. I still think the disulfate function on it is helping get longer life from the batteries. Or it may just be my imagination?

Geo-TH,In · Feb 10, 2023

Most smart chargers will charge and do the job of a maintainer.
I have 5 smart chargers and 18 batteries.

I leave chargers on for a few days, then test the batteries voltage and cranking amps.

I have 3 lawn batteries that may need replaced soon.
They are measuring 12.5v and 200 ca.

Other mower batteries are 12.6v or more and 350 ca.

DoubleR · Feb 10, 2023

I've been using a couple Schumacher 1.5 volt maintainers for the last few years. They have a Yellow lite when charging and a green light when its fully charged. I put it on a battery for a couple days the rotate it to another. They keep about 20 different battery's charged up for me that are all different sizes. I do have a smaller 1 amp Schumacher that keeps my motorcycle batteries charged in the winter. The three of them have worked out good for me.

I have a 1/2 dozen of them Harbor Freight maintainers but don't use them anymore. I had heard stories of them starting fires which I don't know if that true or not but decided not to chance it.

Liquid_wrench · Feb 10, 2023

Won't be long George, rural king will have their riding mower batteries on sale. I need 2 of them this year.

Woohoo!

Geo-TH,In · Feb 10, 2023

Yes, I know. I usually buy 2 or 3 350 cca mower batteries and put them on the workbench. Come summer I'll need them.
I use mower batteries in mowers and both Terramites, Farmall C, Kaw mule and 2 electric generators.

dpendzic · Feb 10, 2023

I had one in my old Int dump truck--checked it once and the black box was all melted on the front seat--must have burned the hot wire feed and put itself out--now i make sure they are on a non flammable surface

Liquid_wrench · Feb 10, 2023

3 riders, 1 generator, Kubota, Massey and Deutz batteries are bigger. Last year I needed pos on left and someone switched the plastic pos plastic tab at the store so I had to go back. lol

Mark-Mi · Feb 10, 2023

I have a mix of a dozen of this or the newer 1.5 amp model.
I put one on four group 31 batteries in semi. Leave on all winter no problem.
Maintainer

Bob M · Feb 10, 2023

I've kept a BatteryMinder Plus 1 amp maintainer on my truck (two group 31 batteries) for several years.

In winter the truck sits unstarted for a month or two at a time - the maintainer keeps the batteries up just fine (the BatteryMinder's green light flashes which indicates it's sensed the batteries are full and it's in maintain mode).

As far as I'm concerned it works great.

da.bees · Feb 10, 2023

If batteries are fully charged before hooking your 850ma maintainer up it will maintain and desulfate them just fine. If one or both batteries are less than 75% charged it will require several days to charge them. I run the small Deltrans and never hook them up to large or multi batteries unless they are already charged. Discharged batteries are charged with a 6/2 amp chargers,never with boost charger.

Hobo,NC · Feb 11, 2023

(quoted from post at 11:09:10 02/11/23) I've kept a BatteryMinder Plus 1 amp maintainer on my truck (two group 31 batteries) for several years.

In winter the truck sits unstarted for a month or two at a time - the maintainer keeps the batteries up just fine (the BatteryMinder's green light flashes which indicates it's sensed the batteries are full and it's in maintain mode).

As far as I'm concerned it works great.

maintain mode formal name is float mode.

Float mode is where the voltage on the battery is maintained at approximately 2.25 volts per cell, or 13.5 volts for a 12V battery. This voltage will maintain the full charge condition in the battery without boiling our electrolyte or overcharging the battery.

Float mode is not a charging mode. It will take at least a 1amp maintainer to maintain two group 31 batteries.

Charging/maintaing a battery is not talked about much in the automotive world. Yes, it is in the marine/RV world, you have to research it in those applications.

Three Stage Battery Charging

Battery maintainer

Bob Bancroft

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Russ from MN

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JoeM(GA)

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BarnyardEngineering

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Mike M

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Geo-TH,In

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DoubleR

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Liquid_wrench

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Geo-TH,In

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dpendzic

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Liquid_wrench

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Mark-Mi

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Bob M

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da.bees

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Hobo,NC

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