Dead Car

Newbie57 · July 19, 2025, 19:43

Took the car out for a short run today. Stared fine in the garage and again on the drive. 10 mile run to the fruit farm all ok. When I tried to start it again, nothing. No lights on the dash. Radio doesnt work. Flahing light for the alarm ok.
Called out green flag started on jumper pack. Got home but as soon as I have switched off car is dead again.
Battery shows green on the indicator window. Check the charge seems full but shows 12.2v on the charger.
Any pointers?

Pete McCue · July 19, 2025, 20:12

12.2 is pretty low I think. Can you turn on the headlights? If you can, do they go out if you try to start the car?

jvanzyl · July 19, 2025, 20:18

How old is the battery? Realistically 5 years of pretty much it for a lot of battery's these days.
Get yourself a lifepo.

Gaz mr-s · July 19, 2025, 21:16

If you can start it check the alternator charging voltage.

Turn on headlights & see what batt' voltage does.

Could possibly be an earth issue.

paulj · July 19, 2025, 21:35

Ive known batteries to fail but still show the green indicator. Dont rely on that - your battery sounds like the issue

Carolyn · July 20, 2025, 09:37

Corroded battery posts? Worth giving them a clean up - and the connectors as well.

Newbie57 · July 20, 2025, 09:51

Quote from: Carolyn on July 20, 2025, 09:37Corroded battery posts? Worth giving them a clean up - and the connectors as well.

I've cleaned the battery posts. No difference. They guy that did the jump start for me suggested the eart lead from the gearbox might be that's or the earth connector on the starter motor.

Carolyn · July 20, 2025, 10:05

Quote from: Newbie57 on July 20, 2025, 09:51I've cleaned the battery posts. No difference. They guy that did the jump start for me suggested the eart lead from the gearbox might be that's or the earth connector on the starter motor.

There is no earth connector on the starter motor.

Beachbum957 · July 20, 2025, 11:57

The battery is most likely the problem as 12.2 is considered only 50% charged. Static voltage won't tell much, so get the battery load tested. A bad battery may show some decent voltage with no load, but completely fail with a load.

Newbie57 · July 21, 2025, 18:02

Borrowed a battery from another MR2 owner in the village (thanks Richard). Fitted and the car starts ok. 😀.
Checked the charging voltage on the ODB. 14.4V.
Checked the battery on the charger after a couple of starts. Charge had dropped to 3 bars but quickly came back to full. Assume that's normal and not an excessive drain.
So looks like new battery required