Battery or alternator?

consumers_revenge

Hi,


Thoughts please?


Wifes car that I rarely drive so haven't seen first hand.


Its a mk1 focus that she claims fails to 'catch' when she starts it. I asked her about the symptoms, lights dimming etc type of noise but shes a bit vague.


Ive recharged it twice now, once a few months ago and when it was flat when we came back from a weeks holiday a week ago ( it did start once after a week then not the next day )


I am thinking its the battery as I don't know when it last got changed and also she only does a few miles a couple of times a week so its not like it gets a decent charge.


However she said tonight that the battery light was flickering twice then went out which makes me wonder if its the alternator instead? However because it was flat after a week I suspect its the battery?


I could leave my focus for a fortnight and that woudnt be flat.


Cheers.

parking_question_chap

I would guess at battery if you never remember changing it and its only used on short drives.

consumers_revenge

That's my guess as even if alternator faulty wouldn't make battery flat within a week if not used

sevenhills

consumers_revenge wrote: »

However she said tonight that the battery light was flickering twice then went out which makes me wonder if its the alternator instead? However because it was flat after a week I suspect its the battery?
I could leave my focus for a fortnight and that woudnt be flat.
Cheers.

Try swapping cars for a couple of weeks?

Battery lights don't flicker for nothing, alternator?

"At Kwik Fit we offer a free battery check at centres across the UK"; and Halfords do a free check too.

Maybe its both, if you are having problems now, you need to find the problem, its summer.

consumers_revenge

This is the first occurances of it flickering at idle btw

Norman_Castle

consumers_revenge wrote: »

However she said tonight that the battery light was flickering twice then went out which makes me wonder if its the alternator instead? However because it was flat after a week I suspect its the battery?

The battery light may flicker if the alternator is struggling to charge a tired or damaged battery.

agrinnall

sevenhills wrote: »

"At Kwik Fit we offer a free battery check at centres across the UK"; and Halfords do a free check too.

Take it to either and it's pretty much certain that they will recommend a new battery, and probably replacement of several other components, whether that's needed or not. I'd suggest that if you can't sort it out yourself you should take the car to a specialist auto electrician.

consumers_revenge

and I don't want any new shocks :-)

consumers_revenge

Found a multimeter so will check for both and might just swap both our batteries over.

almillar

Good, you've got a multimeter. With the car off, test the battery voltage. Roughly 12V is right. Start the car. If the alternator's working, it should now be charging the battery. Check the battery voltage again, it should be roughly 14v.
If it doesn't go up like that, it's the alternator (or other part of the charging system).
If it does, you've got a weak battery. Terrible, weak batteries can still show 12V whilst being incapable of providing the big amps to turn the engine over.

consumers_revenge

OK just test with multimeter


car off - battery is 12.7v
cranking drops to 9.6v ( suspect that's the answer there! )
running no load - 13.61v
running under load - 13.57


deffo thinking new battery!?