Alternator is still not charging
 

Alternator is still not charging

Started by mlh1936, August 30, 2008, 03:36:45 PM

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mlh1936

August 30, 2008, 03:36:45 PM
After my previous post I took my alternator to the repair shop. They replaced the attached voltage regulator. I brought the alternator home and reinstalled it. It is still not charging. When the engine is not running the batt voltage is 12.07. When the engine is running the batt voltage is 11.97. The start batteries are about 3' from the alternator. The wiring looks good and the belts are tight. What do you guys think? Take it back to the repair shop? What else can I do? Thanks.
1987 MCI 102A-3, 8V92, HT-740 conversion in progress.

Sammy

#1
August 30, 2008, 04:07:57 PM
Make sure the voltage regulator has voltage waiting to excite the alternator -  on BAT or IGN terminal of regulator.
Check the regulator wiring on your bus - grounds too.

NJT 5573

#2
August 30, 2008, 09:00:00 PM
Check the big cable that goes from the alt to the switch or batteries. I have seen them burned clear thru.
"Ammo Warrior" Keepers Of The Peace, Creators Of Destruction.
Gold is the money of Kings, Silver is the money of Gentlemen, Barter is the money of Peasants, Debt is the money of Slaves.

$1M in $1000 bills = 8 inches high.
$1B in $1000 bills = 800 feet high.
$1T in $1000 bills = 142 miles high

NJT 5573

#3
August 30, 2008, 09:05:58 PM
Take one side of your jumper cables and hook one end to the big post on the alt and the other end of the same cable to the + side of the battery.
"Ammo Warrior" Keepers Of The Peace, Creators Of Destruction.
Gold is the money of Kings, Silver is the money of Gentlemen, Barter is the money of Peasants, Debt is the money of Slaves.

$1M in $1000 bills = 8 inches high.
$1B in $1000 bills = 800 feet high.
$1T in $1000 bills = 142 miles high

junkman42

#4
August 31, 2008, 09:52:19 AM
Sammy made an excellent suggestion and was right on.  If You are not an electrical person try My point and shoot fix.  Check from ground to all terminals on the regulator.  One terminal should have 12 volts on it with the key or master switch on and the voltage should not  there with the key or switch off.  If that one condition does not exist the alternator will not charge.  Try that test and post back, it will make it a lot easier to help.  John

DrivingMissLazy

#5
August 31, 2008, 12:45:01 PM
Quote from: junkman42 on August 31, 2008, 09:52:19 AM
Sammy made an excellent suggestion and was right on.  If You are not an electrical person try My point and shoot fix.  Check from ground to all terminals on the regulator.  One terminal should have 12 volts on it with the key or master switch on and the voltage should not  there with the key or switch off.  If that one condition does not exist the alternator will not charge.  Try that test and post back, it will make it a lot easier to help.  John

I would suggest doing this with the engine running. There may be a safety circuit that prevents the alternator from charging until the safety circuit closes.

Richard
Life should NOT be a journey to the grave with the intention of arriving safely in an attractive and well preserved body. But rather to skid in sideways, chocolate in one hand, a good Reisling in the other, body thoroughly used up, totally worn out and screaming:  WOO HOO, what a ride

junkman42

#6
August 31, 2008, 05:52:11 PM
Richard, excellent point, I should have thought of that, now You have a clue as to why I am a retired enlisted man!  Old age etc.  regards John
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