I’ve used an expensive tender/charger manufactured by Battery Minder on 12V aircraft gell cell batteries and they have passed the annual 1+ hour rating load tests (30 amp hour battery gets a 30 amp load put on it until it discharges to a min specified voltage) every year for 7 years. The tender has a de-sulfating system that intermittently sends an AC pulse through the battery. Gell cells/glass mat are the way to go, and a de-sulfuring charger will keep the battery healthy for years.. older style wet batteries vent far too much corrosive gas while on a battery tender and eat up the sheet metal…
As HRL mentioned above, some tenders will screw batteries up. I had one that was charging the battery to 14.9 volts- not good!
Last edited by Norcal Dave; 06/07/2022 4:20 AM.
