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eschneider
Jedi Warrior
Offline
Thought I was pretty good with charging systems, but this one is bizzarre.
Car is running out of electricity. Problem has been intermittent - happens 1 day out of 3.
Charge light never comes on. Have had the alternator out, bench tested perfect. Plug was iffy, so I replaced it & soldered the splices. Afterwards it was charging at 13.5V, thought I was done.
happened again, and this time I caught it in the act:
1) key off: battery voltage is 12.6V (yes, not fully charged, I know)
2) running: voltage dropped to 12.3, but slowly CLIMBED to 12.5 over 5 minutes (WTF????)
3) running with headlights on (under load) - battery voltage drops to 12.2, but still climbs slowly....
4) turned key off, battery voltage returned to 12.6.
My guesses at this point:
1) internal short in the battery under load, confusing the regulator?
2) regulator has an intermittent fault - but what fault would limit the charging voltage to 12.3 (and climbing?)
3) intermittent fault in the ignition key switch (but both wires on the alternator plug show battery voltage).
BTW - on a late-80's Mazda 323, Hitachi internally regulated alternator.
Car is running out of electricity. Problem has been intermittent - happens 1 day out of 3.
Charge light never comes on. Have had the alternator out, bench tested perfect. Plug was iffy, so I replaced it & soldered the splices. Afterwards it was charging at 13.5V, thought I was done.
happened again, and this time I caught it in the act:
1) key off: battery voltage is 12.6V (yes, not fully charged, I know)
2) running: voltage dropped to 12.3, but slowly CLIMBED to 12.5 over 5 minutes (WTF????)
3) running with headlights on (under load) - battery voltage drops to 12.2, but still climbs slowly....
4) turned key off, battery voltage returned to 12.6.
My guesses at this point:
1) internal short in the battery under load, confusing the regulator?
2) regulator has an intermittent fault - but what fault would limit the charging voltage to 12.3 (and climbing?)
3) intermittent fault in the ignition key switch (but both wires on the alternator plug show battery voltage).
BTW - on a late-80's Mazda 323, Hitachi internally regulated alternator.
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