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My battery charger died. Again.


The battery in our 2000 Expedition is acting up. I put a "smart?" charger on it, but it wouldn't charge it. It said it had an internal short. I'd picked that charger up used and it had a habit of not charging a battery if it was too low. I wanted a second opinion so I put my old fall back charger on and it wasn't getting the job done. No sparky when I was connecting it live. I put a meter on it and it was only putting out a feeble 9 volts or so. Transformer was bad. Shorted turns? I had redid it once many years ago now. I had replaced the selenium rectifier with 2 paralleled bridge rectifier modules and the transformer with around a 500 watt one I had around. I had the transformer I had kept all these years from the first microwave oven I ever had. I had even stripped off the hi voltage secondary winding when I had saved it. So yesterday I wound a few turns on it, energized it, and found it put out just over 1 volt per turn. I had some #8 stranded and lost count winding it on. I wired it up, the rectifiers were all good, and I connected it to a pulled, but still good, battery, and it showed 15+ volts. I think I'll unwind a half or maybe a full turn. I'm thinking I'm going to put an autoreset circuit breaker on it.

Well I was closer to 16 volts. I pulled 2 1/2 turns. Now with no load, my meter shows 13.5vdc. I have it connected to a 80 ah battery and so far its voltage shows 14.1v. I'll let it charge for a while before I decide if I need to pull another half turn.  Well it's 14.49vdc now. I'm pulling another half turn.


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