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DIY battery charger generator: Confusing problems with the alternator, it's not charging.

natdak

Dec 23, 2021
1
Joined
Dec 23, 2021
Messages
1
Im living off grid and its dark and cold here in Sweden. I've built a generator to charge the batteries, its worked for about 2 hours in total, and ive tried 2 alternators. By this point I'm frustrated and hoping that I'm making a silly mistake somewhere and not just burning alternators.
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I'll do it in chronological order. I built the generator. I started it for the first time without a battery connected and swapped and fine tuned the belt. (this is what my neighbour thinks is the problem, but after the second alternator not working either I'm not so sure) Connected battery to it, flicked the switch, no charging. Realised I had the led light round the wrong way, turned it, charging! (my neighbour also thinks it could have been the led light but after testing a normal one still didn't work). During charging the light would come on every 10 seconds, voltage drop, change in engine noise. Alternator pulley getting warm. I tightened the belt, light came on every 30 seconds, thats an improvement and no more hot pulley. I got maybe 2 hours total of charging on different days. The day it gave up it had been running for only 5 minutes. The light stayed on permanently, motor on or not and there used to be a little noise inside the alternator when switched on and no motor. That has gone. I checked connections and fuses, all good (I think), checked wiring diagram, correct, and changed to normal light (5w) still no cirgar.

Then I got a new alternator and mounted it. (both are bosch 90a). I tested the light (halogen) before starting the motor by flicking the switch, worked. Turned it off, started the motor, flicked the switch, no light, no charging. Turned off the motor, flicked the switch again, no light. I removed the light and tested it by itself and it works. And that's where I'm at.
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Seen here is my connections. The wire goes from the main pole B+, through 10a fuse, switch, light and to the coil pole D+
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This is the wiring diagram for an alternator similar to mine. And the image below is the correct connection for my model. Mine differs from the image above in that it doesnt have an s wire and the colours dont correspond.
yw2up6xg2k681.jpg

Some stats on the engine is Honda HRS536C lawnmower, 160something cc, revs up to around 3400rpm and the pulleys are 3:1 ratio.

Cheers, Nathan
 

kellys_eye

Jun 25, 2010
4,876
Joined
Jun 25, 2010
Messages
4,876
Running the alternator WITHOUT a battery will cause alternator regulator failure.

If you have more than 2000rpm at the alternator it should charge - is the battery in NEED of a charge?
 
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