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post #1 of (permalink) Old 09-22-1999, 07:56 PM
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lazy charging system

i have an 85 bronco with a EFI 302. my prroblem is i have 12.5 volts not running. running i have 13.8 volts. then if i turn on my headlights it drops down to 13.2 volts then drops some more to 12.6 volts. i replaced and propertly tenchioned the belt checked and cleaned all connections, checked the fueseable link and related wireing . and replaced the regulater a few weeks ago. my altinator is a pepboys reman from 2 years ago and my battery and cables are a year old. i am thinking i may have burned out the altnator with all my lights. i have 220 watts of driving and 110 watt fog lights. 150 watt back up lights. i rember when i turned on my headlights my charge gage would move up. then when i turned on some more lights it would go up some more. now it moves up a little bit with headlights, stop with more on. and only move up at highway speed.
in real need of help

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post #2 of (permalink) Old 09-23-1999, 01:47 PM
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Re: lazy charging system

The easiest and quickest is probably to take your alternator to a parts store that can test them. Have them explain to you what their doing every step of the way, so you can figure out if THEY know what they're doing! Some background info:Years ago, General Motors Delco alternators had a spot on the back or side of them that you could stick a screwdriver into to "full field" them for troubleshooting. The screwdriver would short to ground part of the field winding circuit (taking the regulator circuits out of the picture) and run full field current on the alternator. With full field, the alternator would make as much power as it was capable of at that shaft RPM. So voltage should go up, lights get brighter, and engine load down a bit more. At that time, FORD didn't have anything handy like that. Somewhere, I remember reading about that again in relation to FORD. You might want to see if you have one. It was obvious... a tab sticking out at the bottom of a cutout. Not like poking a screwdriver through a vent slot or anything like that. By the way, working voltage for lead-acid battery cells is 1.85 v at the bottom of charge, 2.2 v at the top. Measured with a good voltmeter, after the battery has "rested" (say 1/2 to 1 hour no current in our out). Multiply per-cell voltage times 6 for the standard 6-cell 12v battery. Also, good charging voltage on a fully-charged battery is roughly 2.35v per cell. I wondered... with all of the lights you've got, Jim, can they see you from the Space Shuttle? Hope this helped, UncleDon.

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