low battery after 6 month repair wait. Topic is solved

[jonesg]

Yeh, another battery/alternator puzzle, seems to be a rash.
2004 V70 225k miles. runs good otherwise.
Battery was $200 3 yrs ago.

I blew my radiator at xmas on a snowbank, had it towed to a garage and told them no hurry. Then covid screwed everything up and it sat...and sat.

Finally got it back yesterday after 6 months.
Drives great but today after a 20 minutes 60 mph hiway trip I got the low battery warning as I pulled into a store lot.

I drove home, battery reads 11.65v , under load I think.
but only 11.45v with engine idling.

It has no problem starting, fires almost instantly but after a minute idling the battery warning returns.

I'm curious if its possible the repair shop disturbed something around the alternator, its in that area with the hoses and all. Its also possible I knocked something loose when I hit the snowbank.

Lower voltage when idling suggests to me the alternator isn't putting anything out or is disconnected.

any ideas guys ?

[RickHaleParker]

If it been sitting for 6 months. It may have severe plate sulfation. Put the battery on a charger for two days or longer. Preferably a battery charger with a pulsed desulfation mode. It would help if you had access to a clamp on amp meter. The Alternator might be dropping voltage because a defective battery is maxing out the current.

[jonesg]

Thanks, I'll give the charger a shot and see what happens.

[abscate]

I’ve been charging my neighbors batteries during Covid lockdown as a public service.

$25 plus $25 shop supplies.

[jonesg]

I’ve been charging my neighbors batteries during Covid lockdown as a public service.

$25 plus $25 shop supplies.

I'll put a stamp on it and send you mine. !


Neighbor lent me a known good battery, same story as mine,

over 12.8v engine off.
11.8v with the engine running.
Increased rpm tp 2k+ , didn't seem to make much difference if any.

what does that tell me, voltage regulator?

[abscate]

Something is pulling that voltage way down

[oragex]

Neighbor lent me a known good battery, same story as mine,
over 12.8v engine off.
11.8v with the engine running.

The alternator is not working at all. Check the red cable to the alternator, otherwise I'm thinking the regulator is bad (but check the pulley and bearings as well). Maybe also look closely at wires at the cooling fan connector. Don't discard your battery, it was simply discharged, so may work properly with a good alternator

[jonesg]

Neighbor lent me a known good battery, same story as mine,
over 12.8v engine off.
11.8v with the engine running.

The alternator is not working at all. Check the red cable to the alternator, otherwise I'm thinking the regulator is bad (but check the pulley and bearings as well). Maybe also look closely at wires at the cooling fan connector. Don't discard your battery, it was simply discharged, so may work properly with a good alternator

Yes, it appears so,

I left the battery on charge for 30 hrs, 2 amps, with occasional 10 amps.
Today it reads 13.3v after it settles down.

Pulling the alt looks like unfun.
Just reaching in with a hand is nearly impossible to check wiring, is there better access from beneath ?

[jonesg]

Something is pulling that voltage way down

I tried a parasitic draw at the battery neg post,
got strange reading. I'll try again and see what it says.

[RickHaleParker]

Where are you measuring the voltage? Across the battery or at the alternator.
Do both and see if there is a difference under the same conditions.

Dirty battery terminals. Loose or dirty B+ connections. Loose or dirty grounds.
It is not uncommon for one to forget to reconnect a grounding strap.