Ford Ka - RAC tell me its alternator, not so sure now!

Honest John Back Room » Technical matters
What is life like with your car? Let us know and win £500 in John Lewis vouchers | No thanks
View Threaded
Thu 5 Sep 2013 12:46
Ford Ka - RAC tell me its alternator, not so sure now! - Taffy Laith

My wifes Ka broke down and the RAC guy told me it was the alternator - so had the alternator changed. Started the car after changing alternator and gave it a good drive to try to charge the battery back up, but as soon as I stopped and tried starting the engine again - NOTHING!

I've tried charging the battery at home but it loks like the battery has gone down in charge! Could it have been the battery all along?

Note: Before the car broke down the first time, the wipers were staggering and not working smoothly??

Thanks in advance guys!

Reply | Report as offensive | Link
Thu 5 Sep 2013 13:24
Ford Ka - RAC tell me its alternator, not so sure now! - Galaxy

Yes, the problem could certainly have been the battery. I would have thought the RAC guy would have tested it, though.

Most places who sell batteries will test your battery for free. If you have tried to charge the battery but it won't accept a charge then I would guess the battery has had it.

The only other thing to consider is whether anything is causing a permanent drain on the battery, e.g. boot light staying on all the time.

I would never believe anything that a road patrolman told me about a car fault without making or having done further investigations.

Edited by Galaxy on 05/09/2013 at 13:25

Reply | Report as offensive | Link
Thu 5 Sep 2013 23:58
Ford Ka - RAC tell me its alternator, not so sure now! - Peter.N.

Connect a voltmeter across the battery with the engine running, if the alternator is charging you should have about 14.4 volts across it.

Reply | Report as offensive | Link
Thu 5 Sep 2013 23:14
Ford Ka - RAC tell me its alternator, not so sure now! - Avant

Moved to Technical.

Reply | Report as offensive | Link
Fri 6 Sep 2013 22:38
Ford Ka - RAC tell me its alternator, not so sure now! - Cyd

It could have been a faulty alternator.

It could have been a faulty battery.

It could be both were faulty. Perhaps one as a result of the other.

We'll never know now.

BTW, you'll never properly charge a battery by driving around. Use a charger.
(and in any case, using a charger is way cheaper than burning petrol)

Reply | Report as offensive | Link
Sat 7 Sep 2013 09:47
Ford Ka - RAC tell me its alternator, not so sure now! - thunderbird

BTW, you'll never properly charge a battery by driving around.

Since appox 1976 I have been driving cars with alternators, before that it was dynamos. In that time I have never had to charge a battery and only had to replace 2 which had failed due to age. In all that time I had presumed it was the alternator charging the battery.

If it wasn't the alternator what has been charging the battery.

Reply | Report as offensive | Link
Sat 7 Sep 2013 10:03
Ford Ka - RAC tell me its alternator, not so sure now! - elekie&a/c doctor

The issue with alternators is that they are not able to charge a very low battery.They will only maintain and replace the charge in a good battery .So driving around trying to replace the charge in a flat battery is pointless.If the battery has any chance of recovery,then it will need a very slow charge on a mains charger.This is more of a problem on modern day batteries.hth

Reply | Report as offensive | Link
Sat 7 Sep 2013 19:30
Ford Ka - RAC tell me its alternator, not so sure now! - Cyd

Thanks HTH

www.theaa.com/motoring_advice/news/car-battery-lif...l

Reply | Report as offensive | Link
Sat 7 Sep 2013 21:24
Ford Ka - RAC tell me its alternator, not so sure now! - medview

Hi

It is my understanding that once a car battery has gone really flat it is damaged and unrecoverable. Perhaps this happened following your alternator failure?

If a car battery goes high impedance the car alternator will not be able to provide enough terminal voltage (above 14.4V) to partially recover the battery.

Joe

Reply | Report as offensive | Link
Sat 7 Sep 2013 22:10
Ford Ka - RAC tell me its alternator, not so sure now! - skidpan

The batteries used today in most cars can die almost instantly with no warning wheras years ago they could struggle on for weeks with increasingly poor starting. Think its called calcification. Happened to me about 5 years ago, Friday car started perfectly, sat all day Saturday, Sunday dead as a dodo with just loads of lights flashing on the dash and various relays clicking. Voltage was 12.4 volts (below the 12.65 of a healthy battery), tried charging but it would not accept any. Battery replaced and all OK.

Reply | Report as offensive | Link
Sun 8 Sep 2013 15:23
Ford Ka - RAC tell me its alternator, not so sure now! - Cyd

Hi

It is my understanding that once a car battery has gone really flat it is damaged and unrecoverable. Perhaps this happened following your alternator failure?

If a car battery goes high impedance the car alternator will not be able to provide enough terminal voltage (above 14.4V) to partially recover the battery.

Joe

This can happen, but not always in every case. Even a good battery can be damaged by deep discharge, but there is greater risk with a poor one. It seems likely to have been the case here. A faulty alternator which is not providing sufficient charge will allow the battery to gradually discharge, which may or may not damage the battery. The driving cycle may also have an effect, particularly if it is made up of short journeys and cold starts (which are harder on the battery.

Reply | Report as offensive | Link

Looking for a garage you can trust? Honest John's Good Garage Guide has thousands of reader recommended garages, plus how-to guides and tips on servicing.

The Good Garage Guide