I noticed going to work in the mornings the car seemed sluggish starting when it was cold. The other day it was the coldest it has been this year. The car turned over slowly and didn't start. I got jump leads and it started and i drove it home. Next day the temperature was 7c so i tried to start it and it fired up, so i went to local car shop and bought a new battery. i came home and fitted the battery and everything seemed fine. drove the car about a couple of times that day and it was fine. The next day i went out and started the car but the dash lights were coming on (battery, abs etc,..) so i didn't want to risk driving off. i parked up oitside the house and switched it off. I tried to restart but it was flat. My mate turned up with the jump leads and we fired it up again. i tested the voltage across the battery while it was running and it read 12.1 v. It was the same with revs held at 3000rpm and with the lights on or off. I also noticed a high pitched sound coming from the engine over the last few days. Is it the alternator that's faulty? If it is why would it keep running after being started with the jump leads?

12.1v with the engine running is too low.

did you fit a silver calcium battery?

Should be looking for around 13-14v if your alternator's doing its job.. a high pitch noise could be a belt slipping meaning the alternator isnt spinning? :)

I fitted a banner battery model no p 7209 starter battery. It's the battery that the car shop gave me. i brought it home and when fitting i noticed it was smaller than the original ford battery. I phoned them and they said it was the right battery.I also checked the banner official site and it seems to be the right battery (even if it is smaller) How do i test the alternator and check if the belt is slipping?

Hi, you test an alternator with a volt meter. you need at least 14 volts up to 14.6 volts at revs of around 2500rpm, as a rule you need more in than is coming out of the battery.