My first impression (and assumption) was that the big coil in the middle was the transformer, and I had thought it was used to step the voltage down from household 110V AC to something lower, then passed into a rectifier to obtain DC voltage somewhere near the 14.4V maximum for lead-acid battery. It also meant I could easily follow circuit board traces to see how much I understand. It’s almost refreshingly retro to see a circuit board with only through-hole components. I also note that this label (and all the warnings) would not be visible when the device is mounted.ĭisassembly was straightforward with only four screws to remove. Harbor Freight no longer lists item number 99857 on their site. When we want to charge/maintain the battery, we plug an extension cord into its stubby power cord.
It was designed to be permanently mounted under the hood of a car. I got it from a discard pile just to take apart and look inside.
I don’t know why this particular battery charger/maintainer was discarded, but I wasn’t going to hook it up to a real battery to find out.
