I couldn't get any of the "automatic" chargers to work with my car that's sat for a while in the driveway. I have a Schumacher SC-1200A (12A/3A), which I think is discontinued, but it works great other than there's no 12V/6V switch. It just assumes that if the voltage of the battery is under maybe 7V that it's a 6V battery and then applies a suitable voltage. I still have a traditional 1.5A Schumacher automatic maintainer with a 6V/12V switch, but even with the 12V switch it would just indicate that it was "charged".
So the only thing that worked was whipping out the old 1A Schumacher wall wart charger. After a couple of hours the battery was showing about 11.5V and the automatic charger can take over and charge the battery.
If my 1A wall wart ever failed, I'm not sure where to find a new manual charger. I've never really used it other than to revive a battery that more sophisticated chargers give up on.
So the only thing that worked was whipping out the old 1A Schumacher wall wart charger. After a couple of hours the battery was showing about 11.5V and the automatic charger can take over and charge the battery.
If my 1A wall wart ever failed, I'm not sure where to find a new manual charger. I've never really used it other than to revive a battery that more sophisticated chargers give up on.
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