Finally found my charging issues i think

[ThomasE30]

So after a month and a half of having some issues where my car wouldn't be able to turn on after turning it off because the battery would be almost dead, I think I found the problem being the alternator. I did a parasitic drain test and it showed only about 36mA being drawn. I thought it was a drain this whole time because of all the electronics and wiring that's been done by the POs. Do you guys think this could be the alternator? And if it is where would you recommend getting a new one from. Autozone has the duralast one but it says i will have to order in store for about 145 (40$ core refund), O'Reilly has an ultima for $150, and on Amazone i can get a BBB Industries 14782 for 135$. I've heard people say they'd trust junkyard ones more than parts stores but sadly e30s here are rare to find, especially just in a junkyard and i don't know if i trust myself enough to rebuild it.

[Heezea]

I just replaced mine with the one from Amazon. Not sure about how the durability will be but looked very similar to the old model. I may order a rebuild kit so I'll have the other as a backup down the line.

You can 100% confirm the alternator by checking voltage to the battery with the car running at idle and at about 2000 rpm. In either case, you should be getting 14+ volts with the car running as the alternator charges the battery. In my case, I was only getting 12 volts at idle but 14V with a light rev. Then again, mine was squealing, so that was also a major clue.

[ThomasE30]

I just replaced mine with the one from Amazon. Not sure about how the durability will be but looked very similar to the old model. I may order a rebuild kit so I'll have the other as a backup down the line.

You can 100% confirm the alternator by checking voltage to the battery with the car running at idle and at about 2000 rpm. In either case, you should be getting 14+ volts with the car running as the alternator charges the battery. In my case, I was only getting 12 volts at idle but 14V with a light rev. Then again, mine was squealing, so that was also a major clue.

So to confirm the alternator just turn the car on and rev around 2000 and the multimeter should read around 14 while revving and while idling?

[Heezea]

Yes that is correct.

If you don't see 14V+ your charging system (alternator) is not keeping up with the battery use. As a sanity check, you can do the same test on a car with a known good alternator to see the 14V+ you should be seeing.

[roguetoaster]

That test only works if the battery is actually healthy. If the battery has an issue it can show a false positive bad charging system.

OP, above 13.4 to 13.6v when operating at idle is fine, but 14ish is optimal. It should be remembered that these cars as standard don't tax the charging system the way a modern car might, so they seem to be more tolerant of marginal states of charge.

Also remember, check your grounds.