Why does my battery keep dying

bobsnow100 · Post by **bobsnow100** » 18 Oct 2012, 13:36

Hi,
Car- 2001 volvo xc70 turbo. 240,000 miles
My wifes car ramdomly will get a dead battery. The car will be fine for days or weeks and then she may drive to the store and shut it off andcome back out of the store and the battery is dead. Could happen in as little a 2 minutes. Needs a jump start . Car may be fine after that for weeks. The headlights are always bright so I am guessing the alternator is good. I did replace the alternator a few months back thinking it could be that,same symtoms.
The battery does charge up and has been tested by 2 different places and is good.
It appears that sometimes it isn't being charged while driving and other times it is
I have heard that it could possibly be my ecm. Something in the computer telling the alternator not to charge the battery.
Does that sound correct. If someone knows something about that ,please let me know

Post by **coflynn** » 18 Oct 2012, 14:26

Hello,

The alternator has a hardwired connection to the battery, there is no way for it to be 'turned off' by the ECM. It's possible the voltage regulator or alternator is flaking out? It's also possible the connection at the front is bad too.

I have a few tips at https://www.matthewsvolvosite.com/forums ... =9&t=51058 - I think it should be similar if I'm not mistaken to your car (I could be mistaken!).

You can probably get the regulator pretty cheaply & it's not too bad to install how I suggest, so if you don't want to do a lot of in-depth troubleshooting could be something to try. How old is the battery? If it's sufficiently old would consider replacing it anyway, rather than having it die and keep you stuck somewhere...

Regards,

-Colin

Post by **JDS60R** » 18 Oct 2012, 16:06

I have found parasitic drain issues with the 01. Tonight , exit the vehicle and do not lock it with the remote. Once the interior lights shut off check the light at the ignition key cylinder on the side of the steering column. See if it stays on?

I have had this wear down batteries and cause no start conditions on an 01 V70.

If it wasn't that - do a parasitic drain test.

CountryBum-kin · Post by **CountryBum-kin** » 18 Oct 2012, 18:43

Loose connections at the battery, alternator, or starter solenoid can produce the conditions you describe. If possible, get a cheap volt/ohm meter and leave it in the care. The next time this issue occurs check the battery voltage (should be roughly between 12.7-and 13 volts). If the voltage is in range look it is time to elsewhere for the problem.

bobsnow100 · Post by **bobsnow100** » 19 Oct 2012, 10:15

I don't think it a parasitic drain. Take for example yesterday. Car has been fine for 2 weeks, no problems. Yesterday she started it the morning , did a couple errands went back to the car and the battery was drained enough to only get a clicking sound from the starter . I got the jumper cables and jump started her. She drove the rest of the day and it was fine. This morning it was fine. It just happens at any time. I have checked all battery connections and actually changed the negative cable because it didn't seem to get tight enough without me being able to twist it loose after it was fully tightened.
I have changed the alternator (got a used one ) ,didn't change anything. I also changed the starter a few months ago( also a used) and that didn't change anything either.
Just last week ,it started having a problem turning the key in the ignition. Put the key in and you couldn't turn the key until repetitive tries.
Maybe a new ignition switch?

Post by **coflynn** » 19 Oct 2012, 10:47

When you say 'battery dies', I assume you mean when you go to start you see the lights dim etc as the motor is trying to start. Is that the case?

If you are getting a working car, but just clicking, that may be a different problem!

mbreed · Post by **mbreed** » 19 Oct 2012, 14:16

How old is your battery? Some tests are better than others. You may want to replace it. I had similar problems not long ago. Battery always tested good. I replaced the battery and the problem is fixed.

Post by **fazool** » 19 Oct 2012, 18:25

As unintuitive as it sounds, I think its a simply a bad battery.

If it has a lot of electrolyte residues and such causing internal shorts, it can be very intermittent. And tests are not that reliable for intermittent problems (I spent months working on battery testing for an industrial application).

If something is draining it that quickly and intermittently, I would suspect a large current flow path, such as a bad solenoid.