2001 V70: Replaced Alternator but Battery Keeps Dying

BostonPeter · Post by **BostonPeter** » 06 Jun 2010, 09:03

Here's the problem for my 2001 V70 T5 Wagon:

Used the AC a few weeks back for the first time this season. The car ran fine for a bit - but then the electrical went haywire - AC shut down, windows wouldn't open, etc. Turned the car off - wouldn't restart. Jumped it and got a voltage overload warning.

I took the car to the shop and the mechanic said the alternator was putting 18V into the system vs. the normal 12V - so we replaced the alternator. He then tested the battery and said all seemed good with the battery so no need to replace it. The only collateral damage to the voltage overload was two blown headlights - presumably just fired with the spike.

And then all was great....until this morning.

Drove the car a short distance with the AC on. All was cool (heyo - forum puns). But when I tried to restart the car it wouldn't crank. The battery wasn't completely dead, but also not strong enough for the starter. We jumped it and it drove it drove fine. No voltage issues like before, etc.

Here's the question: Is this a battery issue - meaning it really was damaged by the alternator issue? Or is this possibly some kind of horrible air conditioning issue - where the AC is causing mayhem in the electrical system?

One note - the car has 138K miles and I'm not sure how old the battery is - bought the car secondhand in 08 with 117K miles on it.

Thanks for your help. Cheers -Peter

Retired MVS Contributor · Post by **Retired MVS Contributor** » 06 Jun 2010, 09:28

Have you checked the water in the battery?...The battery is under the rear floor and is often not checked...My cross country is 9 years old and 2 years ago the battery went dead suddenly in the middle of the winter...I charged it up, found out that it was low on water, refilled it with distilled water (from the basement dehumidifier) and it has been fine ever since...The battery is 9 years old, but the car only has 16,000 miles...

BostonPeter · Post by **BostonPeter** » 06 Jun 2010, 09:49

Good question - and yes, I checked it back when the alternator went and the fluid level is fine.

Post by **igel513** » 10 Jun 2010, 15:41

Could there be a short somewhere in your wiring. A simple way to check if you have a short is to have all elec'l system shut off.
Remove negative wire from battery, now rub the end of the wire to negative terminal post, it you see sparks from that contact, there could be a short.

Post by **JRL** » 10 Jun 2010, 15:44

BostonPeter wrote:Good question - and yes, I checked it back when the alternator went and the fluid level is fine.

You checked it?
You put a battery tester on and tested the cells?
Checking water level is not checking a battery (that was 40 years ago)
If this is original, BUY A NEW ONE ALREADY
7 years old, you're lucky it starts at all!!!

billr99 · Post by **billr99** » 10 Jun 2010, 20:34

igel513 wrote:Could there be a short somewhere in your wiring. A simple way to check if you have a short is to have all elec'l system shut off.
Remove negative wire from battery, now rub the end of the wire to negative terminal post, it you see sparks from that contact, there could be a short.

I'm not sure I would recommend this approach on any P2 Volvos. The computer systems, and especially the ECC, are pretty sensitive to how a battery is to be hooked up. Jumping a spark across the battery might send a good jolt thru the system with bad results. I would suggest using a meter or a test light to do the same thing and keep the procedure a bit more controlled.

Cheers,

Bill

Retired MVS Contributor · Post by **Retired MVS Contributor** » 22 Jun 2010, 17:18

JRL wrote:
BostonPeter wrote:Good question - and yes, I checked it back when the alternator went and the fluid level is fine.

You checked it?
You put a battery tester on and tested the cells?
Checking water level is not checking a battery (that was 40 years ago)
If this is original, BUY A NEW ONE ALREADY
7 years old, you're lucky it starts at all!!!

The 100 year old hydrometer is STILL the best way to check a battery...But he did not say he checked the battery's CONDITION by checking the water, he said he checked to see if it HAD water...