Battery tender salvage

July 30, 2014, 09:50:11 AM

I lost 2 battery tenders in a recent thunderstorm. Pretty sure the logic got zapped as I can still get an output bypassing it.

My question is, can I still us the center tap transformer to make a 'dumb' tender and a few off the shelf parts? If so, suggestions?

There is a circuit that creates 13.65 VDC (normal output of a working unit in HOLD mode) which the logic somehow used to drive the SCR's. I tried applying it to gate of the SCRs and get a nice output but when connected to a battery, the output drifts high (15VDC+)

I checked a good unit and when the battery is charged and in HOLD mode the voltage is 13.65VDC and drawing about 100ma. Not sure if the unit limits the current or if that's all a fully charged battery will draw at that voltage??

Will probably replace them with new units but before I toss the old ones figured maybe I can salvage them. Maybe even a little bench 12v supply even though they only supply 2A.

Thanks for any suggestions.....