Black and Decker 25A Battery Charger (with 75A Boost)

What an interesting device. Picked up from amazon for $83, it's not cheap to be sure. The black and decker seems to offer up to 25 DC amps @ 12VDC for charging car batteries. However, when I tried to charge my dead battery, I was unable to even use the boost component. Seems B&D put a 2V DC minimum on the boost circuit; any battery below that would not be fit.

I had to get Canadian Tire to boost my car the old fashioned way. I ran my car for 3/4 of an hour and it came up to 75%.

One problem I discovered with this battery charger is the thing will stop randomly charging for an unknown reason. I may need to take it back. After running for 5 minutes @ 14.05 VDC @ 25.4 amperes (impressive), the machine beeped and stopped running.

Was it hot? The fan was running when the charge was working.

Is the battery fucked? It passed the tests.

Terminals on the battery are very clean because it sits in a protected plastic bucket provided by Mazda. Pushing over 25 amps into a battery is pretty impressive considering the small size of this thing. I imgine it uses AC - DC converter  via switching power supply. I can't see this being a linear power supply due to the light weight of the unit. Linear power supplies are notoriously inefficient and utilize massive transformers. This one does not.

I tried to phone their "Help Line" but sadly, it was a mess; no idea how long I would be "in the queue" and I abandoned the call after 15 tortorous monutes listening to music.

I have better things to do with my time. I'll continue testing and provide updates later this week.