$20 Solar Battery Maintainer

A while back I bought a 15 watt solar panel to keep my tractor battery charged. It was manufactured by Coleman, the lantern/stove people so I figured it was probably a decent unit for the really cheap price they were asking.

I put it on the tractor and checked the battery voltage a couple of days later to see how it was working, and the voltage was lower than when I started!

Pulled out the VOM and checked the output leads from the solar cell, ...and the polarity was reversed.

I'm guesing that the factory cranked out hundreds or thousands that were wired wrong and wholesaled them off to a discounter.

Reversed the leads and everything works fine.

Hard to diagnose the issue from the keyboard. Do you have a handheld multimeter to diagnose an issue with the solar charger? It could also be that since the solar charger was left in a dark garage, hence no charging was done, the parasitic loads of the vehicle may have drawn the battery down to zero. This assumes that the battery was left with the cables connected.

FWIW, I am about to switch my semi-automatic battery maintainer onto a third battery. This device is a walwart 12V, 300 milliamp transformer with two alligator clips. Rather than plug up this thread with details, I'll post up the use and results in a different thread.

You said you were gone several months and had done this same thing in years past without the solar maintainer. Is this the same battery? If so maybe the battery has had it and needs to be replaced. Even the gypo solar maintainers have a diode(s) to prevent electrical back flow during the dark hours.

it's likely a backfeed to the panel

I have a Deltran 15watt trickle charger with a built in controller. Cost more than $20 but it was a gift. Several of the guys in our storage yard have Coleman, or ones from Pep Boys and Cabelas none of them are having problems.

I know what you asked was could it be the charger draining during night sky time. Probably, most likely. But if you're looking for and inexpensive one the three I mentioned might give you some help.

Sometimes we just get what we pay for.