Battery/alternator charge issues

[Mstrshkbrnnn]

So this all started a few months ago when the quarantine first hit. I had to fly across the country for a funeral, and because of that, I left the 96 r in the driveway the entire time. I was gone a little over a week, and hadn’t driven the car for about 2 weeks prior because of a heater core job I had been stalling. When I got back, the battery was completely dead, so I jumped the car. The car started, but when I disconnected the jumper cable, the car immediately died. I suspected, somehow, the battery took a shit on me so I put in a known “good” battery and the car started, but this time all the warning lights stayed on. All the warning lights except for the transmission arrow, and the oil pressure light (thank god). A lot was going on in my personal life so I couldn’t really dedicate the time I should’ve to her so she sat.

About 2-3 weeks after that incident, I decided to start working on her again, so I drove her to my workplace, so that I could address some oil leaks after work. On the drive home, the car stalled, and that scared me because the car had NEVER turned off on me before. I pulled into the gas station to check my battery cable connections and everything seemed fine so I started her back up and drove 10 miles home. It scared me a bit so I decided to not drive her very far. That night, my girlfriend mentioned how she missed riding in her, so we, reluctantly, took her for like a 3 mile spin. On the drive back home, when i was pulling up my very steep driveway, it all of a sudden couldn’t find 1st or 2nd gear, and was stuck in 3rd or 4th, so as you can imagine, the car wouldn’t move up the driveway. I turned her off and I tried restarting her but the battery no longer had enough juice to start her back up. Thankfully, my other car is a manual 240, so I was able to put that battery into the 240, and roll start it. I drove the 240 a few miles to charge the battery back up.

The car has been sitting for a while as I haven’t had the funds to buy her a new battery, and I was honestly too lazy to constantly take the battery out of my daily 240. I recently got a battery, and have been trying to diagnose again. I suspected the cables may possible be bad so I did a volt drop test on both the positive and negative cables. The positive read out between .5-.8 V so I thought, ok it’s the cable. I stole the battery-to-starter and starter-to-alternator cables off a 98 s70 and rechecked. Same thing. Hmmm. Also, while the car is running, the battery is receiving NO charge. While running the battery reads out anywhere from 12.2-12.5. Is it possible that a bad alternator is giving me weird readings for the cable resistance measurement? Or am I lucky enough to have to replace both the cables and the alternator?

Any guidance would be greatly appreciated as when it comes to electrical, I don’t have much confidence, and I find it hard to find a starting point.

[Mstrshkbrnnn]

Also, all the warning lights are still on (except for trans and oil pressure light).

[misha]

Measure the output from the alternator directly with multimeter....positive probe on b+ and negative on alternator housing while engine is idling.
If you don't have 13.8-14.2v ....alternator is shot...or voltage regulator.
Also check a little thin wire above the b+ terminal...if it's disconnected or shorted,alternator will not have output.

I hope that you didn't crossed terminals while jumping the battery with cables.

[Mstrshkbrnnn]

Measure the output from the alternator directly with multimeter....positive probe on b+ and negative on alternator housing while engine is idling.
If you don't have 13.8-14.2v ....alternator is shot...or voltage regulator.

Just started the he car up again and checked. Alternator voltage read out the same as battery voltage. This time 11.9.

[Mstrshkbrnnn]

I hope that you didn't crossed terminals while jumping the battery with cables.

I definitely did not do this. Just curious though, what happens if you do?

[Mstrshkbrnnn]

If you don't have 13.8-14.2v ....alternator is shot...or voltage regulator.

How am I supposed to know which one is bad?

[abscate]

You can try just replacing the voltage regulator but I would take the whole thing to an auto electric shop and have it evaluated and rebuilt

[Mstrshkbrnnn]

You can try just replacing the voltage regulator but I would take the whole thing to an auto electric shop and have it evaluated and rebuilt

I was under the assumption that rebuilding these guys is a no go?? Is my assumption incorrect?? Also, I’ve been doing a lot of reading, and is the b+ cable the single, thin wire that attaches to the positive terminal? Or is it the bundle of wire that attaches to the terminal? Also is there any surefire way to know if the regulator is bad? I’d rather not just throw parts at the car, as I’ve been doing that for months and it’s draining me financially lol. Currently, I’m planning on building new 1 awg positive, and negative cables so that I don’t have to worry about those anymore. If a new alternator is mandatory then I guess I’ll shell out the $200+ for one :/ I’d rather not waste ~$50 on a new regulator and it turns out the alternator is bad too

[misha]

Thin wire is above the thick b+ on alternator.
Get readings from b+ and alt housing.

Thin wire is a signal wire for warning lamp and it's "awakening" for the alt.
Without it or if it's shorted somewhere...alt will not have an output.

[misha]

...I definitely did not do this. Just curious though, what happens if you do?

Fried alternator,relays in fuse box if you are lucky....ecu(s) sometimes survive.