Electrical Rewire required | 1998 V70 | Bad cables and/or bad alternator

yanga001 · Post by **yanga001** » 08 Jun 2021, 16:43

So i measured the voltage drop from the positive terminal to the main fusebox and came up with about 0.2V under moderate load. The voltage from my alternator is very low as i am getting around 13V max across the battery. Im guessing it needs to be replaced ASAP and have a parts one up north i need to recover.

I am wondering about cleaning or rewiring part of the battery to fusebox harness as it has a fairly significant drop. Additionally ill check the starter cable and alternator and post my results.

EDIT:

Measured the max voltage drop from alternator to battery as roughly 0.3 volts
Soldered and cleaned the contacts on battery to fuse box and brought down the max drop to roughly 0.09V.

Alternator seemed to be roughly 13.4 V while idling. The battery voltage under max load was 12.7V

Post by **misha** » 09 Jun 2021, 01:23

Measure alternator output directly on alternator while engine is idling.
Red probe on b+ and black on alternator housing.
You should have 14-14.2v.
If alternator output is 13v...directly on it....voltage regulator or alternator are bad.

yanga001 · Post by **yanga001** » 09 Jun 2021, 07:21

misha wrote: ↑09 Jun 2021, 01:23 Measure alternator output directly on alternator while engine is idling.
Red probe on b+ and black on alternator housing.
You should have 14-14.2v.
If alternator output is 13v...directly on it....voltage regulator or alternator are bad.

Thanks Misha,

The 13.4 was directly on the alternator from the + terminal of it to the frame. I think the bearing went out on it as well as it makes a whirring sound.

Hoping my spares up north are good and worse case will pull a brand new one from a project car.

Post by **erikv11** » 09 Jun 2021, 09:51

yanga001 wrote: ↑09 Jun 2021, 07:21
misha wrote: ↑09 Jun 2021, 01:23 Measure alternator output directly on alternator while engine is idling.
Red probe on b+ and black on alternator housing.
You should have 14-14.2v.
If alternator output is 13v...directly on it....voltage regulator or alternator are bad.
Thanks Misha,

The 13.4 was directly on the alternator from the + terminal of it to the frame. I think the bearing went out on it as well as it makes a whirring sound.

Hoping my spares up north are good and worse case will pull a brand new one from a project car.

Your sig says you have a 99 S70 project car - note the 99 has a different alternator that will not swap to a 98.

yanga001 · Post by **yanga001** » 09 Jun 2021, 13:11

Damn didn't know that, well i guess i can contact a friend in the area for one. Worst case ill rebuild it myself i guess. Thanks for the info!