need battery charge controller?

[stevehull]

Just installed a used driveway gate opener (Apollo) run on deep cell marine type battery with solar back up. The battery is new (deep charge marine type).

A few months ago, I picked up a old used PV panel at a yard sale. Wires were broken off on back and only had short stubs. Had my voltmeter in the truck and tested it (cloudy day) It was putting out some 0.5 A at about 20V. Based on that I offered $2 (they were asking $30) and got it. Just resoldered longer wires to the stubs . . .

Anyway, the label, on the back of the panel is almost illegible, but I suspect the panel is ~ 30 watts (18 inches x 22 inches).

The new deep cycle marine battery, fresh from the auto store, measured 12.5 V and today after one day of full sun is up to almost 15 V (one solar lead removed from battery when measuring this battery voltage).

I will open this gate only 2-3 times a day. With that little load, will I overcharge the battery? If so, what charge controller would you suggest to prevent this issue.

Thanks in advance.


Steve