Car struggling to start - battery? Starter?

[StillLearning]

My 2008 Corolla is having problems starting - the battery voltage is reading 12.4V with the engine off but when I press the Start button it's taking ages for the engine to start.

I tried using jump leads and starting off a car that was running, and it started perfectly 3 times in quick sucession.

The voltage was 14V once the engine was running.

Can I somehow have a dodgy battery even though it was on 12.4V?

[ARHarh]

A healthy battery should be about 12.7v when doing nothing. Try measuring the volts with the lights on high beam or when trying to start it. If it drops below about 8v when trying to start its probably the battery. Also when you have got it started check the battery voltage it should be somewhere around 14v, if it is then the alternator is working OK, if lower the alternator is probably the issue.

[GreenV8S]

That voltage is unusually low, and the symptoms fit a weak battery. I suspect you'll find that the battery has either lost capacity and needs replacing, or isn't being charged properly due to a vehicle fault which needs fixing, or possibly both.

Go to any of the places that supply and fit batteries, and have them test the charging system and load test the battery.

[Peter911]

Check your battery connectors and your earth strap too. These can cause this issue, and the connections to the starter motor.

[StillLearning]

GreenV8S said:

That voltage is unusually low, and the symptoms fit a weak battery. I suspect you'll find that the battery has either lost capacity and needs replacing, or isn't being charged properly due to a vehicle fault which needs fixing, or possibly both.

Go to any of the places that supply and fit batteries, and have them test the charging system and load test the battery.

Is 12.4 too low to properly start a car? The battery indicator thing is green.
When the car is running the voltage is 14V so I think that suggests the alternator is working?

If it was a starter motor problem, would the problem still exist if I was using leads to jump start?

I checked the battery to earth strap and that seems OK- still connected.

[GreenV8S]

StillLearning said:

Is 12.4 too low to properly start a car? The battery indicator thing is green.

12.4 is the offload voltage. The voltage under load is what matters. That's why I suggested you get the battery load tested.

A healthy battery which is fully charged will show more than 12.4V off load. So either it's unhealthy, or it isn't fully charged, or both.

If it isn't fully charged, the problem may be that the battery won't take charge, or the charging system won't provide it, or there is a current drain flattening the battery. That's why I suggested also getting the charging system tested.

You really need to get those tests done and it's pointless speculating until you've done that. They're quick and easy to do with the right equipment.

[ARHarh]

It is why I suggested measuring the voltage whilst trying to start it, if it drops to below about 8v chances ware the battery is shot. If so you can get it tested if you want. My guess is battery is shot.

[E-bmw]

As others have said that is around 50% capacity not fully charged.

Having said that a small-engined petrol car should start all-be-it a bit slowly.

First thing to do is (as others have suggested) PROPERLY check & clean & refit ALL connections on starter/battery/alternator, then fully charge the battery overnight.

When you have done this see how it starts and check the voltage before & afterwards.

[konark]

The cold weather kills batteries thAt have been holding on all summer. 12.4 v is a battery that's on its last legs assuming connections and charging is ok.