Alternator/Battery Problem??

[CycloneMike]

I'm having a few problems.
I bought a new battery less than 12 months ago. Got it from Halfords as I needed it on a Sunday afternoon
It now doesn't want to charge anymore or hold any charge for long. So i took it back as it had a 4 year guarantee. They checked it on bosch hand held tester and told me it was un servicable but not their fault so not guaranteed.
So what does that mean I asked, well there is a problem with your charging system that has done this to the battery. Such as what I asked, well I don't know was the answer.
So anybody know what the problem could be? Voltage at the battery with the engine off is 12.6V, but it cranks slowly and soon runs flat. When running at a few thousand rpm I get 13.5V is this enough?? I had it drop tested by a friend it fell rapidly to 8V then held.
I wondered if I should replace the starter cable, I believe they can build internal resistance with age and cause a voltage loss between the alternator and battery?
Its a Subaru EJ22 if that makes any difference, I also wondered if there would be any benefit in uprating the 70A alternator?
I am loathed to shell out for another battery until I know what is going on.
Any advice apprieciated.
Regards,
Mike.

[Fritz]

Mike , don't quote me on this but they may use the same means of battery testing as they have in most dealerships, where a battery when returned in the warranty period must be tested with a fancy meter which then displays a fault code. If this code fails into a particular catagory then a warranty claim may not be accepted .

I'd phoning the manager to get him to fully explain why they won't replace the faulty item....

Regards,


Fritz,,,,,,,,,,,,,

[bigherb]

The tester has probably picked up the battery is sulphated which is not a warranty fault. As you have only 13.5v charging voltage it would be unlikely the battery has recieved a full charge causing sulphation. Check the connections on the alternator and starter motor if they are ok replace the regulator you should be getting a minimum charging voltage of 13.8v ideally 14.2v.

[HarryMann]

Sounds like it might have been excessively discharged (too many amps drawn for too long) which might have overheated it internally. Or left discharged for a long time (unlikely from what you say). Less likely is continual overcharging...

[CycloneMike]

Thanks all,
Fritz it was one of the managers who tested it.
All connections are good. I think undercharging is the most likely answer. From a quick look, it looks like an exchange alternator job as the regulator is internal and I can't find them listed for sale.
So if it is sulphered up, is this the sort of think that the battery can be recovered from by topping up and put on long slow charge? or is it scrap.
I've disconected the leisure batt (110A) to see if that helps, but it shouldn't make any difference as it doesn't normally have any load on it.

Regards,
Mike.

[glenn77]

Interesting post - i am having pretty much the same problems with mine at the moment - just about to go and buy a new battery too but will keep an eye on this to see what else i can test/ try

[VWCamperfan]

A very slow trickle charge for about a week may bring it back to life. You need the slow charge to desulphate the plates. A quick charge will not allow that reaction to happen and although the battery may appear to be charged, it is simply because the sulphates on the plates are preventing the charge from flowing into the electrolyte and the charger registers no charging amps and appears to have fully charged the battery.
A slow charge will gently dissolve the sulphates on the plates and put them back into the electrolyte.
You cannot fully remove the sulphates from the plates unless you have a battery desulphator connected to the battery while charging. These can be a seperate unit or built into the charger itself... although the ones built into the charger aren't much cop to be honest!

[CycloneMike]

Think I've sorted it. Theres a lesson to learn here, check and double check the basics!!!
I had another look at all of this last night. Voltage at battery with engine idling was now 12.5V which was less than the day before. Resolute to the idea of buying a new alternator I was looking for a part number on it and thought I'd check the votage direct at the engine end. What do you know but 14.5V rising to nearly 15 when the engine was revved. So now I had it in my head the cable was duff. I removed cleaned and re attached all the cables between the alternator and battery. Still only 12.5V at the battery. So its deffo the cable I thought, so to test and I connected the alternator direct to the battery with a jump lead. Again 12.5V at the battery, which blew a big hole in my theory. To cut a long story short and after a bit more testing it turned out to be the battery earth attachment to the van body. Although apparently good, tight and clean as soon as I attached the earth cable elsewhere it sorted the problem, 14.5V at the battery. The threads of the clamping bolt had corroded.
Just have to hope the battery can recover with a bit of trickle charging.
Thanks for your help.

[Fritz]

Mike, we all forgot to mention that your alternator won't charge at all during idle. It is simply designed that way .

Regards


Fritz.......