Like a dummy, I connected my SLA charger to the battery backwards last night, heard a 'crack' and smelled the magic smoke. I connected it to the battery without the mains connected yet, by the way.
I pulled it apart and fixed it, (only a track was damaged), but in the process was reminded of it's unusual switched-capacitor configuration when I looked at the schematic. (I 'reverse-engineered' it years ago, and drew up a diagram.)
I just thought someone might be interested in the circuit. Works really well, using only a 9VAC transformer.
Also, it originally it charged to 14.9V, a bit high for my liking, so I modified it for 14.2V.
The circuit, a bit rough but readable:-
Luckily, due to it's design, the current path was back through the diode bridge, only allowing 1.2V of reverse voltage across other components for a moment until the track was no more, which did no damage.
Working fine again now.
I pulled it apart and fixed it, (only a track was damaged), but in the process was reminded of it's unusual switched-capacitor configuration when I looked at the schematic. (I 'reverse-engineered' it years ago, and drew up a diagram.)
I just thought someone might be interested in the circuit. Works really well, using only a 9VAC transformer.
Also, it originally it charged to 14.9V, a bit high for my liking, so I modified it for 14.2V.
The circuit, a bit rough but readable:-
Luckily, due to it's design, the current path was back through the diode bridge, only allowing 1.2V of reverse voltage across other components for a moment until the track was no more, which did no damage.
Working fine again now.