Since my mower decided to die, I built a little battery charger since I had a free battery....sort of.
I've got it turned way down as those leads aren't going to take a lot of current, but it works. That little board under the DMM is a charge regulator I picked up at Tayda (though these are sold nearly everywhere)..thus the charger-on-the-breadboard. Unfortunately, the goop used to attach the heatsink was leftover PlayDoh from 1966, and the heatsink was loose in the package....also, it doesn't work so the heatsink isn't really an issue. I ran an audio probe through it, and it hissed at me

. The only thing worth a hoot on that board is the relay, which is likely what is FUBAR.
Schematic...