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I have a 96 p38, i have a mysterious battery drain but i think i have rectified it. Now i think i have a charging problem. When the car is running at idle, the voltage at the alternator is 14.07v, but the voltage at the small alternator wire that goes to the becm is only 13.56v. Is that wire supposed to have voltage at that level or should it be higher? Please advise. Thanks!
 

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Not really sure but I think batt is 12.6v So alt is at 14v and after a length of wire 13v suppose there is a loss between the two. Is voltage drop
normal or is it just amp drop normal? I know the more wires in proximity the bigger the wires need to be to carry the required current. So not
really helping just thinking.
 

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hammerma said:
Not really sure but I think batt is 12.6v So alt is at 14v and after a length of wire 13v suppose there is a loss between the two. Is voltage drop
normal or is it just amp drop normal? I know the more wires in proximity the bigger the wires need to be to carry the required current. So not
really helping just thinking.
huh?

1. Battery Voltage Across Battery Terminals before starting any tests, no loads on___________
2. Engine off, all accessories on for 30 seconds, then off. What voltage ______
3. Voltage across battery at idle (no electrical load) ____________
4. Voltage across battery at 2000rpm (no electrical load) ________
5. Voltage across battery at 2000rpm (everything electrical switched on) _________
6. Voltage at ALTERNATOR at 2000rpm (everything switched on)___________________
7. Voltage drop between alternator body and battery negative (YES negative). Measure at max electrical load and 2000rpm ______________ (millivolts please)
8. Voltage drop between alternator positive and battery positive. 2000rpm, max electrical load _____________
9. Check Voltage drop from Battery Negative terminal to 1st groundpoint on vehicle______________
10. Check voltage drop from 1st ground point to block__________
11. Check voltage drop from Alternator Housing to block__________
 
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