Using a 2 watt coleman battery maintainer to keep batteries alive when not in use.

rp3703

Just for peace of mind, I’m trying to figure out if these coleman battery maintainers will keep my batteries alive through a Northern Ontario winter. I paired my 6V 215 AH batteries to make them 12V and attached a maintainer to each pair. The maintainers state they can deliver 15V @ 133 mAmps. Other than that, I can find no other info on them. Is it possible to make a good estimate of the viability of them keeping the batteries alive?

mcgivor

Northern Ontario winters are generally cold so self dischargeing would be of little concern if fully charged, left disconnected in an unheated space. Leaving something connected, in your absence could fail in undesirable ways. When fully charged a flooded lead acid battery will not freeze until -70°C, upon returning fully charge before use. Attached pdf provides information 

Estragon

With no controller between the panel and battery, I'd be a bit concerned there may be nothing preventing the batteries from keeping the panel warm. Maybe there's a blocking diode stopping higher voltage batteries from discharging into a lower voltage panel, but I wouldn't count on it without testing.

In a Northern Ontario winter, the batteries will be pretty cool most of the time, and have lower self-discharge. With no loads and fully charged, they should be fine from ~Oct-May.

706jim

Another voice saying just leave them alone over the winter.

rp3703

In case it was not obvious, I was asking whether this would work after the fact. I left my batteries like this at the end of last season and now I'm freaking out that they will be dead or after hearing from you guys, exploded with battery acid running all over the floor.

mike95490

I've got a battery maintainer, and it has a red LED that lights when charging.  It could be wired for forward/indicator and reverse/blocking, not sure if LED specs can handle 15Vrev bias

BB.

I have had very good with Battery Minders

https://www.amazon.com/BatteryMINDer-Model-2012-Maintainer-Motorcycles/dp/B005EKY1EM

On car batteries (that are rarely driven). Regular chargers and cheap float chargers would cause long term loss of water.

When the charger reads full you can move to the next set of batteries (1 or so days of charging). Reconnect every 30 days of 70f or 20c. If batteries are very cold (near or below freezing) then very low self discharge.

Bill

mcgivor

rp3703 said:

In case it was not obvious, I was asking whether this would work after the fact. I left my batteries like this at the end of last season and now I'm freaking out that they will be dead or after hearing from you guys, exploded with battery acid running all over the floor.

Hopefully no damage has occurred, the charger, according to specifications, can provide 2W under optimum conditions, being that the winter sun would be weak and of short duration, optimum conditions are unlikely, so if it could manage 50% output for 2 hours the voltage would likely remain well below 15V. Hope everything is fine.

Estragon

> @rp3703 said:
> In case it was not obvious, I was asking whether this would work after the fact. I left my batteries like this at the end of last season and now I'm freaking out that they will be dead or after hearing from you guys, exploded with battery acid running all over the floor.

Most likely, the batteries are fine. If not, all you can do is make contingency plans. Freaking out won't make any difference to the batteries.

Earlier advice about leaving batteries alone for the winter was based on a ~Oct to May period when it's cool/cold. As it usually does, it warmed up in early May, with a few days near 30°C since, so having a maintainer may not be a bad idea.