Battery Light

Mr. Detail · Post by **Mr. Detail** » 24 Sep 2021, 16:17

Ok, the previous owner of my V70 installed what I thought was a pretty good battery in 2017. (INTERSTATE)
Supposedly it is a 6-year battery and would last to perhaps 2023.
Last weekend I mistakenly left the parking lights on all night. The car started up fine afterward but today driving home
from work, I got an error message "ELEC/POWER SYSTEM SERVICE REQUIRED".
Is it possible that I killed the battery early?

Post by **jonesg** » 24 Sep 2021, 18:28

check the small plug on the back of the alt. look for loose or corrosion inside plug.

Two different indications can happen.

1. Red battery warning light means the serpentine belt broke or battery/cables loose etc.

2. Warning dialogue in the driver information window point to the alternator not energizing because the signal from the ECU isn't getting through via the signal wire.
When the small signal wire is disconnected the red battery warning will NOT illuminate.

jking4020 · Post by **jking4020** » 24 Sep 2021, 19:29

I just dealt with this problem last week with a new 2001 V70 XC I bought. I put my battery in that was next to new in it and "service electrical system" light came on. I had to swap out alternators. Use a multimeter and check the alternator while the car is running. If the alternator is less than 13 volts than the alternator is crap. The battery I have in it I mistakenly left my lights on as well three times. Had to jump start it a few times. The alternators in these cars rarely go bad but it's probably that.

darylrobert · Post by **darylrobert** » 25 Sep 2021, 00:51

I had a faulty alternator when i bought my car, it would stop working when it got hot, i got the "battery low" warning but ignored and drove faster but car died on interstate. i think when you finally see a warning the battery is almost dead.

If your doing short drives then the battery doesnt have enough time to charge, or your alt needs looking at. Buy a trickle charger.

Mr. Detail · Post by **Mr. Detail** » 25 Sep 2021, 05:33

Thanx guys! Yes, I do have the small red battery warning light on plus the error message about "ELEC/POWER SYSTEM SERVICE REQUIRED".

Mr. Detail · Post by **Mr. Detail** » 25 Sep 2021, 11:52

OK. Just did the unthinkable and took my P2 to a Pep Boys for electrical diagnosis. The only game in town on a Saturday.
They checked both the battery and the alternator. They told me the battery had nothing left in it and the alternator was reading 10 volts. I find it hard to believe that both would go at the same time so I will ask for your recommendation.

Replace the battery first since the tech said that the alternator may be reading low because of the almost dead battery?

P.S. The damn tech left off the plastic battery cover and proceeded to bolt down the metal bracket right on top of the terminals!
That is how I found it after barely making it home.

Post by **volvolugnut** » 25 Sep 2021, 14:26

Service conditions can cause a battery to discharge or fail before the warranty period ends. Most times a discharged battery can be recharged using a remote charger, but it may take as much as a day. A discharged battery may not provide enough voltage for the alternator to work and charge the battery while the engine is running. A charging alternator should produce about 14 volts at the battery.

Free diagnostics may be expensive.

volvolugnut

Mr. Detail · Post by **Mr. Detail** » 25 Sep 2021, 18:28

volvolugnut, who said it was free?

Post by **Blacklab467** » 25 Sep 2021, 20:33

You should have 13.6 V or so at the B2 terminal at the alternator with the engine running. If the alternator is only throwing 10V the battery state of charge is almost guaranteed to be coincident with the alternator problem and is probably fine. Change the alternator.

Post by **jonesg** » 26 Sep 2021, 03:51

Its more likely to be the voltage regulator on the alternator, $45.