Is There Anyway Of Testing A Battery

[john-melbourne 6]

Hi guys,

 

I have been having problems with a flat battery on my cti recently, the car would jump start but nit put any charge in the battery at all. I have since found my -ve battery terminal was loose so borrowed the father in laws battery charger to give it a charge. Just plugged it in and the charger says the battery is full! unfortunately the car is not with my at the moment so I can't go and out it back on and test it that way, is there another way of seeing if the battery has a charge in it?

 

Thanks Guys

 

John

[Baz 421]

If you haven't got a proper battery drop tester then no, not really. You can very crudely short-it out to give a rough idea how much grunt it has in it, but it's not always reliable tbh...

[welshpug 1,656]

Pop in to any of the fast fit centres, they all seem to have drop testers and many do reasonable prices on Batteries too.

[john-melbourne 6]

Do halfords have the facility to test batteries?

[Anthony 1,002]

The larger stores often do (go to the parts desk) and larger motorfactors will do.

[john-melbourne 6]

just been to halfords, the battery is dead apparently. It wouldn't even turn there machine on! so that means my charger must be duff as well!

[PeterGriffin 20 1 Cars]

not sure about that mate, wouldn't the "full" signal on the charger come on when there's no current flowing into battery..?

[john-melbourne 6]

Managed to get a different charger, and after 2 days the battery is half charged, must have been really dead Just waiting for it to charge then i can put it back in and test the alternator.

[chipstick 382 1 Cars]

I'd say there's a chance it was more the battery being knackered than the charger not being up to it. Give it a test again after you've looked at the alternator. Often batteries that discharge that badly or that quickly are beyond the point of saving.

[john-melbourne 6]

Just put the battery in the car and it started first time, checked the voltage and it was 13.8v then put the blowers and lights on and after about 10 minutes it had dropped to 12.5v, turned the lights off and this slowly started going back up again. Unfortunately i cant get anyone to rev the car while i test it.

 

Can anyone help with what these readings actually mean?

 

Thanks Again

 

John

[welshpug 1,656]

means the alternator is on its way out.

[john-melbourne 6]

means the alternator is on its way out.

 

Thanks welshpug, is that a difficult job to replace or something an amateur could attempt?

 

Also is this a common fault with 205's? The reason i ask is i have had a look through all the receipts that i got given for my CTI, they go back 20 years and total a fair amount of money! The car has seemingly had 5 alternators and 4 batteries, is this normal?

 

Thanks Again

 

John

[welshpug 1,656]

very easy, Grab a Haynes workshop manual, don't forget that pro's are rare on here, we're all amateurs at one point

 

as for the number its had, were they decent units or used?

 

I replaced mine 7 years ago with a Hella remanufactured unit from GSF.

[Slo 283 1 Cars]

don't forget that pro's are rare on here, we're all amateurs at one point

 

Never has a truer thing been said

 

Easiest alternator test is pull a terminal off while its running and note if the engine dies or slows down.

I know people always say not to do that because it can damage the alternator internally but i've never had a problem yet

[john-melbourne 6]

very easy, Grab a Haynes workshop manual, don't forget that pro's are rare on here, we're all amateurs at one point

 

as for the number its had, were they decent units or used?

 

I replaced mine 7 years ago with a Hella remanufactured unit from GSF.

 

Looking at the receipts, 4 were new alternators and one was supplied by owner according to the receipts

[GLPoomobile 958]

Just put the battery in the car and it started first time, checked the voltage and it was 13.8v then put the blowers and lights on and after about 10 minutes it had dropped to 12.5v, turned the lights off and this slowly started going back up again. Unfortunately i cant get anyone to rev the car while i test it.

 

Can anyone help with what these readings actually mean?

 

Thanks Again

 

John

 

1) If you can balance the Voltmeter in bay so that you can see the display from the drivers seat (through the gap in the bonnet), you should be able to see what's happening when you rev it

2) Failing the above, you can rev the engine from the front by twisting the throttle by hand. You just turn the black plastic bit on the throttle body, where the throttle cable is attached

3) I would confirm the alternator is at fault by measuring the voltage there rather than at the battery terminals. So connect your voltmeter +VE probe to the +VE cable on the alternator, and -VE probe to an earth

4) If the voltage is still low at the alternator, rev the car above 4000rpm and hold the revs there for a few seconds and see if it increases then. This is when the alternator "self excites", which would point to a problem with the excitor wire if this happens (IIRC)

5) This is probably the most important bit, make sure the batteries in your voltmeter are healthy or you could get spurious readings. I replaced a good alternator that I thought was over charging, and had the same reading with the replacement alternator until I realised the battery in the voltmeter was failing. Replaced that and got the correct values, and realised I'd swapped out the alternator for nothing.

[2-Pugs 57]

Some good advice here. The only thing I will add is that I think you will definitly need a new battery. From experience once a battery has gone completely flat like that they are never quite the same again. As I understand it the lead comes out of the solution in the battery and migrates to the plates (called 'balling up', apprantly!) which significantly reduces it's capacity. You might be able to charge it up and get a bit of life out of it but it's only a matter of time before it'll let you down again.

 

Do the tests GLP suggested but it sounds like your alternator has had it too, so replace that.

 

I would also suggest checking and cleaning all the relevant wiring and connectors.