battery or alternator? ?

S3_chris 11

S3_chris 11

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I started the car tonite and left it to warm up and de mist the windows, came back and everything had gone dim inside and out, battery warning beeped, threw up all warning lights on my dash. I pulled off the drive went down the road it jerked and came back to life, headlights on dash lights on and no warning lights on or problems.

The battery is only 7months old, could it be that or the alternator?

And since we are talking about batteries, just a strange concern, is any of u guys batteries a snug fit in the battery tray/holder as mine is not :s

All help and views appreciated

Thanks guys and girls
 
My battery fits the tray exactly, and has a jacket on it too.

What battery is it? A good one?

It could be giving up the ghost at the first sign of cold weather?

You need a volt meter to check the output voltage at the alternator, it should be 14+ volts if healthy.

The battery should be putting out 13 volts or so.

Both the above with the engine running.

My alternator was good, but battery voltage was low (11.8v) even though it was new. My fault was a dodgy earth in the charging circuit on the engine block, and high resistance too. I cleaned the earth up and replaced the positive cable from the alternator to the battery, and all has been good since.
 
Previous batteries have been a snug fit with the jacket on, but my latest Exide battery wouldn't fit in the jacket, so I left it off, it's about an inch wider, very tight.
 
S3_chris 11 said:
I started the car tonite and left it to warm up and de mist the windows, came back and everything had gone dim inside and out, battery warning beeped, threw up all warning lights on my dash. I pulled off the drive went down the road it jerked and came back to life, headlights on dash lights on and no warning lights on or problems.

The battery is only 7months old, could it be that or the alternator?

And since we are talking about batteries, just a strange concern, is any of u guys batteries a snug fit in the battery tray/holder as mine is not :s

All help and views appreciated

Thanks guys and girls
Click to expand...

Seeing as the battery is only 7 months old, it seems a long shot that it's that that's causing your issues, but it well could be.

Personally, I think it probably the regulator pack on the rear of the alternator.

Have you got a multi-meter? If so, check the voltage at the battery with the engine at idle. It should be around 14V. If not, I'd suspect the alternator or at least the regulator.

To be definitive, you'd need to bash an inductive ammeter (or amp clamp) around the out put cable of the alternator and check the output amperage of it. Not sure what it should be for an A3, but I'd say between 50-100Amps (complete guess btw!) If not, it's your alternator or alternator regulator.

Hope that helps dude.
 
Ps. I've got a 110 amp hour battery in my A3 and it's ace! ****** huge, and hangs about 3 inches over either side of the battery tray and the cover definitely doesn't fit! Been like that for three years and it still had enough charge in it to start the car after sitting for 6 months without moving! (I "acquired" it through work, thus putting up with its poor fitment)
 
The battery came from exhausts unlimited. The one I was replacing had 2handles and this one is now a one handled one. I told them it didn't look right but they told me it's the right one for the amk engine. If I had a jacket on it there would still be bout an inch of room the whole way round the battery. Looks awfully small considering the one that I took out. I haven't got a volt meter/multi meter anymore as all my tools got robbed out my shed. Where can I get this checked (for free) lol
 
Get a decent Bosch silvertop from GSF, should be about £80, never buy anything from high street tyre/exhaust monkeys
 
S3_chris 11 said:
The battery came from exhausts unlimited. The one I was replacing had 2handles and this one is now a one handled one. I told them it didn't look right but they told me it's the right one for the amk engine. If I had a jacket on it there would still be bout an inch of room the whole way round the battery. Looks awfully small considering the one that I took out. I haven't got a volt meter/multi meter anymore as all my tools got robbed out my shed. Where can I get this checked (for free) lol
Click to expand...

Screwfix do a multimeter for about £13 I think, pick one of those up. It'll be useful for other stuff too.

The problem with taking it somewhere to get it checked is they will most likely try and sell you something you don't need!

A girl at work got a flat battery by sitting in the car and leaving the heater running/radio on for a long lunch break. She called the AA who duly arrived and 'tested' the battery, announcing it was very low on volts/amps, and she needed a new one which he had on the van for £110. She called her husband and he said just get a boost and drive home, which the AA man did with dire warnings etc and said he wouldn't attend again if she stalled etc. The battery was charged and has been fine for months since. Ok, it wasn't in the first flush of youth, but lots of places will tell you your battery is screwed when it isn't.

Yours does sound a bit on the small side though, and could have developed a fault from being overworked?
 
Will there be any difference if the wrong battery is fitted? As what I think they have done is gone by the cars original model and not the engine. The battery is working fine tho just low voltage from the alternator think it was about 11.83v. So is it the alternator at fault? And what would you guys do bout this wrong battery business? Take it back and ask them to change it due to their own incompetence
 
Last edited:
They also told me I should have an 096 battery or an 027 and what I've got is an 079. I'm pretty sure I used to have these on my 1.8 8v mk2 golf lol
 
the alternator, loads of load on and a weak battery, at idle

as soon as you drove and got the alt spinning faster it made more power
 
7 months later/ a few thousand miles later and they gonna do a straight swap for a Bosch 096 battery. Is it worth getting an alternator too??
 
If its only putting out 11.83v, then yes. That's measured at the alternator, correct?

If its at the battery, then check the earth points underneath the battery tray and the engine block.

A healthy alternator should be 14.6v or thereabouts. The battery voltage when the engine is running should be 13v+.

The correct battery will help, but if its not being charged properly then it will all be downhill from here.
 
fitted the bigger battery today, everything is soo much brighter than what it was before and the engine sounds so much more healthier when turning over. so now instead of having 300 cold cranking amps (cca) i now have 650 cca.

.
 
does anyone know the correct alternator for my car before i have to take it off? as there is 2 to choose from so ive been told, different amps
 
cheers guys i dont understand why they tried to sell me 2 different kinds one was 120a and i think the other was like 96a or something, is it an inlet off job as there doesnt look like much space
 
It is tight, but possible if you remove the stuff over to the left hand side of the engine bay (covers/aux drive belt/belt tensioner) and move some pipes out of the way (no need to remove them though).

You don't need to remove the inlet manifold though, fortunately!!
 
I have just ordered a new battery. Being a bit of a newbie, are there any do's and don'ts?

I don't want to lose my radio code etc. Vaseline on the terminals?

Thanks.
 
vanilla_ice said:
I have just ordered a new battery. Being a bit of a newbie, are there any do's and don'ts?

I don't want to lose my radio code etc. Vaseline on the terminals?

Thanks.
Click to expand...
Removing the battery you will have to re enter the radio code and grease on the terminals can't hurt keeps the water off them and stops corrosion so you have a good connection
 
Thanks for the reply. Is Vaseline suitable? Alternatively I do have copper grease.

Do the terminals need to be on silly tight?

If I can't find a record of the code is there any way of extracting it from the radio?

I said I was a newbie!
 
vanilla_ice said:
Thanks for the reply. Is Vaseline suitable? Alternatively I do have copper grease.

Do the terminals need to be on silly tight?

If I can't find a record of the code is there any way of extracting it from the radio?

I said I was a newbie!
Click to expand...

If its the original radio, I don't believe you will need the code.

The code should be with the vehicle docs anyway, on a card.

Ive had my battery disconnected many times and never needed to enter the code.
 
You only need to re-enter the code on early 8L's, pre 2000. 2000+ cars use the CANBUS on the radio so it remembers
 
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