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[Chimpchoker]

My car failed top start a few months ago so I charged the battery up and the car started. Wen t to the evil mother in law and after a couple of hours tried the car and it wouldn't start. The AA said it was the rectifier stopping the alternator charging the battery. With the engine reving at 3000 rpm he said that the battery was only cvharging to 12 v so I'd need a new battery and alternator.

Last night in bed I remembered that no red light had come on in the dash, nor any of the other lights once the engine was started.

I'm wondering if this is just a case of a nashed battery and not an alternator problem because of the lights not coming on in the dash. The electrics have never been tampered with EVER so this would rule out damaged wires / missing bulbs etc in the dash.

The AA man said not to buy a battery before checking the alternator out as if the alternator is not working proprerly it will burn out the new battery. The current battery is about 4 - 5 years old. If I can get the car started again I reckon I should be able to check the error codes but until then any advice good folks.... 

[Andy B]

.... I reckon I should be able to check the error codes but until then any advice good folks.... 

No error codes for a knackered battery or alternator  you need a proper auto sparks with a battery discharge tester & a multimeter 

[Kevin Wood]

On some faults the red light will come on, others it won't.

Check the security of the crimp where the large cable attaches to the positive battery terminal.

Oh, and I'd be very surprised if it's both the alternator and battery. One of them will be fine.

Kevin

[TheBoy]

Assuming the deep discharge has not screwed the battery (won't have done any favours), its probably just the charging circuit.

See Kevin Woods guide on checking it, and Mark DTM Calib's guide on Alternator refurb (or see if Pinky has a spare)

[TheBoy]

Should add, when Mrs TB's alternator failed a couple of months back, she said the light came on dimly and briefly.

I just went to scrappy and picked up a replacement for £20, whilst I decided on whether or not it was worth refurbing old one...  ...tempted just to pick up another one from scrappy, nick the reg/rect off it, and put it on here old one...

[Chimpchoker]

thanks folks. I read kevins guide on testing the set up and charged the battery fully for over 10 hours. The resting voltage was stable at 12.67v then I put it under load, tried to start the engine and it went to 10.2v and stayed there !
 
I phoned halfords this morning as the garuntee doesn't run out until the 28th of dec ( 4 yr garuntee) and the bloke said to charge it up overnight and try it all again as his wife only does short journeys and with the heater, radio and lights on in this weather she doesn't get to drive far enough to put the full charge back in the battery........

So that's sorted.... drive further.....
Thanks again.

[Kneepad]

Don't let Halfords fob you off with that. If the battery is still under guarantee then you should insist. Tell them it's not holding a charge.
 I did and got a new battery, but they gave me a lot of verbals about needing to charge it properly and I was only using it for short journeys.
Stand up for yourself man. 

[Andy B]

....
 
I phoned halfords this morning as the garuntee doesn't run out until the 28th of dec ( 4 yr garuntee) and the bloke said to charge it up overnight and  .....

do you have a proper auto spark local to you? If so, he'll have a proper discharge tester
 
Ask him to test it for you, and you can then always say that **** auto spark has confirmed that it's fubar'd 

[Kevin Wood]

thanks folks. I read kevins guide on testing the set up and charged the battery fully for over 10 hours. The resting voltage was stable at 12.67v then I put it under load, tried to start the engine and it went to 10.2v and stayed there !

Classic symptoms. The battery has a dead cell. I'd get them to replace it.

Kevin

[peterm]

i had smae sort of problem on my vecy flat bettry one moring gave it a jump and all seemed ok ni light on dash and was runing ok so left to run for a time the shut of when out  latter and away she went only to stop a bit later but just befor i did red light cam on giving game away and aa man tried telling me alternator was gone as well as battery  so go recon as local scarppys wanted 70 not for second hand and i got recon for 990 with disco nuts and batteys been ok and to prov a point not used vecy in week onlky to go out other day hit key and away she went
so much for aa battery teaster or is that a digital mulimter nothing like a good old battery load toaster

[Chimpchoker]

Thanks for the help. I had no intention of Halfords fobbing me off,lol. So, I played by their rules and charged it again for 24 hours (and 3 minutes) and it stabalised at 10.2 v so I used a spotlight to do a discharge on the battery. It was a 55w halogen bulb and it barely lit. The meter went down to 6.3 v then back up to 10.2. Done this a few times and the same results.
Went back to halfords and kept the garuntee in my pocket. Told them I had a problem and could they test the battery for me. They tested it and said there was a shorted cell so it wasn't servicable and I needed a new one at £110.00

Oh I said, I remeber this battery is under garuntee still. Got a new one but the "new" garuntee only lasts three weeks,lol.

My question now is if the original battery had a shorted cell is that likely to be my alternator?

I ask as I don't want to risk putting the new battery on and blowing that before asking you estimed peeps for advice.

Thanks again in advance.

Chimpy

[Kneepad]

Thanks for the help. I had no intention of Halfords fobbing me off,lol. So, I played by their rules and charged it again for 24 hours (and 3 minutes) and it stabalised at 10.2 v so I used a spotlight to do a discharge on the battery. It was a 55w halogen bulb and it barely lit. The meter went down to 6.3 v then back up to 10.2. Done this a few times and the same results.
Went back to halfords and kept the garuntee in my pocket. Told them I had a problem and could they test the battery for me. They tested it and said there was a shorted cell so it wasn't servicable and I needed a new one at £110.00

Oh I said, I remeber this battery is under garuntee still. Got a new one but the "new" garuntee only lasts three weeks,lol.

My question now is if the original battery had a shorted cell is that likely to be my alternator?

I ask as I don't want to risk putting the new battery on and blowing that before asking you estimed peeps for advice.

Thanks again in advance.

Chimpy

You sneaky devil that you are. Well done.

It's unlikely that the alternator is faulty but to be on the safe side have a read of this excellent guide by Kevin Wood for checking it.   


http://www.omegaowners.com/forum/YaBB.pl?num=1225724099

[Chimpchoker]

Thanks kneepad. I read the first bit about the discharge and that got me to the idea of the battery so I'll stick it on when the wife comes home to help open the bonnet, then I'll do the rest of the checks.

Just didn't want to stick the battery on and crank it over and blow the lot up but my trusty multi meter will see action tonight.

[Chimpchoker]

It looks like it was just the battery as I followed Kevins excellent tests but if I may, can I post the reading here just for confirmation.
Engine cranked over, idle speed 13.4v
increased rev to 2000 rpm 13.74v
idle speed and load (full beam lights) 13.4 v
increased rev to 2000 rpm plus full beam load 13.4v

My interpritation is that the alternator is not over charging the battery but the concern of only getting 13.4v at 2000rpm with load means that the alternator is not charging  the battery enough. It might be that this is a new battery that has been on the shelf a while and needs a good run to boost it but the cheapest check of the alternator at a garage in pools is in the region of £70....!!

TIA


Chimpy

[Kneepad]

 It does seem a tad on the low side at 2000 revs with load, but as you say the battery could have sat on the shelf for a long time.
Give it a while, take it for a good run and let the alternator do it's work.

Why don't you tighten up the bonnet cable?