Hello everyone, I have a recent charging issue with my e30...it is an 87 ETA with an OBD1 converted M62B44 with a brand new Bosch 140amp alternator and a new Napa AGM battery.
First off, the battery light in the cluster does illuminate and extinguish on startup. While the battery is discharging, the light does not illuminate, however.
At idle at startup with no accessories on, it will sit at 13.6v. When the electric fan kicks on, it will drop to about 13v...if I turn the A/C and wipers on, and hit the brake pedal, it will discharge down to 9v to the point the wipers won't operate and the engine wants to stall. If I rev it up, it will rise to about 11v with all of these accessories on.
If there is no excessive load, the charge will rise to 14v without issue. I just don't see how a 140amp alternator can have this much of an issue with a car that came with a much lower amperage one.
I replaced the alternator through FCP's warranty thinking that was the issue, however, there was no change. The old one and this one tested good. The battery was replaced as well. Again, no change. I also tried a spare DME with no change there either.
My last thought is the gauge cluster. I am going to try another, however, I am confused as the battery light does illuminate on startup as it should...however, it does not illuminate when the voltage drops, which I find odd. Also, it charges sometimes...so that is odd.
I'm just looking for any experience or ideas where else to look. I did the M62 swap about 5 years ago and haven't had an issue with it until recently with this, and I'm pulling my hair out trying to figure out if its swap related or somewhere in the body. Also, is it normal for the brake lights to create such a large voltage drop?
TL:DR - 87 E30 - OBD1 M62B44 swap - 140amp alternator is unable to keep up with stock e30 electrical demand. Alternator and battery confirmed functional. Battery light turns on and off at startup but does not illuminate when voltage drops below 12v. Any incite?
First off, the battery light in the cluster does illuminate and extinguish on startup. While the battery is discharging, the light does not illuminate, however.
At idle at startup with no accessories on, it will sit at 13.6v. When the electric fan kicks on, it will drop to about 13v...if I turn the A/C and wipers on, and hit the brake pedal, it will discharge down to 9v to the point the wipers won't operate and the engine wants to stall. If I rev it up, it will rise to about 11v with all of these accessories on.
If there is no excessive load, the charge will rise to 14v without issue. I just don't see how a 140amp alternator can have this much of an issue with a car that came with a much lower amperage one.
I replaced the alternator through FCP's warranty thinking that was the issue, however, there was no change. The old one and this one tested good. The battery was replaced as well. Again, no change. I also tried a spare DME with no change there either.
My last thought is the gauge cluster. I am going to try another, however, I am confused as the battery light does illuminate on startup as it should...however, it does not illuminate when the voltage drops, which I find odd. Also, it charges sometimes...so that is odd.
I'm just looking for any experience or ideas where else to look. I did the M62 swap about 5 years ago and haven't had an issue with it until recently with this, and I'm pulling my hair out trying to figure out if its swap related or somewhere in the body. Also, is it normal for the brake lights to create such a large voltage drop?
TL:DR - 87 E30 - OBD1 M62B44 swap - 140amp alternator is unable to keep up with stock e30 electrical demand. Alternator and battery confirmed functional. Battery light turns on and off at startup but does not illuminate when voltage drops below 12v. Any incite?
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