Is battery nackered?

Cyber-Mav · 26 Nov 2021 at 16:06

Had trouble starting, car volt meter showed 9.8v this morning so cranked it and it did slowly start but got issue with head unit resetting itself and my headlights turning off and on.

Put battery on charge, it charges up real quick but if sat for 20mins or so after the charge its resting voltage is 10.5v
That means its time for new battery yeh? 10.5v means one cell is drooped?

andy_mk3 · 26 Nov 2021 at 16:14

What do you mean by charges up real quick? After charging you will get floating voltage. I would try charging for at least 6 hours before condemning it. After charging, turn on the headlights for 20 seconds then back off, then check the voltage. If it's still no good after then then it's battery time.

Alibaba99 · 26 Nov 2021 at 16:26

If the charger appears to indicate that the battery reaches a fully charged state for more quickly than you would expect for the starting level and it doesn't reach 12.8v then that is a pretty good indication that a cell has gone.

Cyber-Mav · 26 Nov 2021 at 16:27

Its a smart charger it charges up to 14.4v then drops to float 13.3ish.
Once i take it off the charger and let it sit it drops to a rest voltage of 10.5v
Will try putting it on trickle charge mode overnight

Janesy B · 26 Nov 2021 at 16:34

Cold snaps always seem to kill off batteries.

Cyber-Mav · 26 Nov 2021 at 17:46

Come to think of it i don't think I've ever had a battery fail in summer. Always winter lol.

Rich1988 · 26 Nov 2021 at 18:49

10.5 is deader than a Dodo. new battery time!

Rroff · 26 Nov 2021 at 18:55

Cyber-Mav said:
Come to think of it i don't think I've ever had a battery fail in summer. Always winter lol.

It is what the service manager said to me after my battery failed "some tests" (rather vague) at the service and MOT it was in for - it would be fine over the summer but next lot of cold weather would kill it according to him - he was mostly right as once winter came it was struggling though still starting the engine.

I think they were hoping to sell me a new battery at the time though.

Cyber-Mav · 26 Nov 2021 at 19:20

Does seem sus when it was at 10v then put on charger and it hits 14.4v in around 20mins.
Cant be charging up fully that quick

dlockers · 26 Nov 2021 at 19:37

Rroff said:
It is what the service manager said to me after my battery failed "some tests" (rather vague) at the service and MOT it was in for - it would be fine over the summer but next lot of cold weather would kill it according to him - he was mostly right as once winter came it was struggling though still starting the engine.

I think they were hoping to sell me a new battery at the time though.

Tbf sounds like you needed a new battery :cry:

dlockers · 26 Nov 2021 at 19:37

Cyber-Mav said:
Does seem sus when it was at 10v then put on charger and it hits 14.4v in around 20mins.
Cant be charging up fully that quick

It's dead

Cyber-Mav · 26 Nov 2021 at 21:27

Got to try and beat the dead horse

ShiWarrior · 26 Nov 2021 at 21:45

when ever i check my battery whilst hooked up to the car, its always above 11v
so id say its knackered

Rroff · 26 Nov 2021 at 23:45

dLockers said:
Tbf sounds like you needed a new battery

It still works now like 2 years on - my dad is using it to power lighting in one of his sheds - last time I talked to him was still holding a charge at 12.6V. It just struggles a bit with high current draw.

I was planning on changing it anyhow as I had no idea on the history of it and doing a lot of driving at night I don't like surprises.

bainbridge · 27 Nov 2021 at 07:46

Yep, new battery time.

Cyber-Mav · 27 Nov 2021 at 11:32

I think it may have resurrected it self. Float charger holding it at 13.3v this morning (battery in car and charger connected). Unlocking and relocking doors didnt tank the voltage was going down to 12.7 then back to float 13.3v.
Will crank it up later and see how it is.

ShiWarrior · 27 Nov 2021 at 21:06

you must have put it on a charger that does "maintenance mode" i.e. trickle charge

i know mine does , and it helps to build the cells so to speak

Battery conditioners restore the capacity of lead acid batteries by targeting lead-sulphur deposits which reduce the battery’s ability to hold charge. These deposits build when a car is repeatedly driven on shorter trips or is left unused.

Diagro · 29 Nov 2021 at 20:28

I've started to trickle charge my car every few days since it started to go below 10c.

Did it last night for 13 hours.
Came back to a nicely charged battery.

SkodaMart · 29 Nov 2021 at 21:51

Just replaced my battery.
Still charges great and holds a charge.
Trouble is the cold cranking amps are now approximately half what they should be 300 vs 540A.