Has the alternator died?
Has the alternator died?
Author
Discussion

rickprice

Original Poster:

498 posts

268 months

Tuesday 15th May 2012
quotequote all
Folks, some advice if you would.

The car has never held charge for long, and its getting worse slowly. A recent lay-up of about 2 weeks meant the battery was dead, which has become the norm , although having owned her for almost 10 years is much worse than when she was new.

Last night, driving home with the lights on, the heater and a fairly loud stereo (with amplifier in boot), after 20 minutes all power drained and she all but coasted to a halt. Luckily this was half way up my drive, but still.

As she died, all the lights were dim, the stereo did not have enoug power to drive the amp, etc.

10 minutes later was just about able to start her and move her up the drive without the lights on.

I have always assumed that I had battery drain because of the poor electrics but now I cannot account for the loss of electrical power / charge with the engine running.

Any clues as to the likely culprit?

Many thanks,

Rich


TV8

3,553 posts

205 months

Tuesday 15th May 2012
quotequote all
How old is the battery? Test the voltage from the alternator outputs with a meter and see what you get.

rickprice

Original Poster:

498 posts

268 months

Tuesday 15th May 2012
quotequote all
Battery only 2-3 years old. Can get it changed under Halfords warrantee, I think, to be sure.

Will spend some time under the bonnet this morning to see whether I can test the alternator.

Rich

Bassfiend

5,530 posts

280 months

Tuesday 15th May 2012
quotequote all
Even if your battery is cream crackered then once the engine is started the alternator should provide enough power to keep everything on the car running *AND* charge the battery as well ...

On the serp Chims the alternator is a 100A unit and should be more than man enough but if it's a pre-serp then it's a 65amp alternator and I guess then it's possible if you have a *HUGE* stereo (and I doubt you have anything that draws that much current - my last big system I could get to draw just shy of 400A but that was only on the bench when stress testing the amps, in normal use it rarely drew more than about 30) that the stereo could be drawing more than the alternator can produce but the battery should be your reservoir for that as the car electrics won't be continually drawing more than the alternator is producing.

I'd seriously look at your alternator as being the *CAUSE* of your problem - not sure where you are geographically but I have a "spare" that you could throw in as a test if you've a serp engine. It has a voltage stability issue but charges just fine and would give you a known charging alternator to use as a benchmark before you go buy a new one.

I'm surprised though that your ignition warning light isn't coming on if the battery isn't being charged.

Unfortunately it is likely that if your battery is being deep discharged / flattened then you have probably killed that too ... thank God for Halfords replacing under warranty!

Phil

rickprice

Original Poster:

498 posts

268 months

Tuesday 15th May 2012
quotequote all
They will replace it if they deem it faulty...

Once the car is charged enough to fire up I'll stick a voltmeter on the back, and try not to give myself a sizeable jolt.

Rich

Bassfiend

5,530 posts

280 months

Tuesday 15th May 2012
quotequote all
rickprice said:
They will replace it if they deem it faulty...
Better than that - they'll replace it if it simply doesn't hold enough charge to satisfy their tester (no matter how it got knackered) and, given that their tester *SEEMS* to be a little biased towards rejecting batteries as faulty (possibly so they can sell people lots of "new" batteries when they test them maybe) then that kinda works in your favour. ;-)

rickprice said:
Once the car is charged enough to fire up I'll stick a voltmeter on the back, and try not to give myself a sizeable jolt.

Rich
Nah - no jolts - it's only 12v and very safe ... just don't short anything that's at 12v to a ground and you'll be fine.

Phil

pk500

1,975 posts

242 months

Tuesday 15th May 2012
quotequote all
Check the fuse underneath attached to engine mount 100amp in a plastic casing

rickprice

Original Poster:

498 posts

268 months

Tuesday 15th May 2012
quotequote all
pk500 is on the same wavelength as the local TVR garage, who will lift it up on their ramp tomorrow. Will let you all know who gets the prize...


Thanks for all the advice. Frustratingly, the simplest fix (fuse) is the hardest to get at, given that I have a gravel drive and do not feel like jacking the car up on gravel and then sliding past the jack to find a black fuse box, painted black with chassis protector stuff...

Will let you know how I get on.

Rich

pk500

1,975 posts

242 months

Tuesday 15th May 2012
quotequote all
mine blew the plastic melted away got a pack of 10 new fuses and a holder was very a cheap fix judge

BillC99

348 posts

190 months

Tuesday 15th May 2012
quotequote all
My 100A fuse was only loose and the battery didn't charge.A quick tweak with a spanner and all was well again.

rickprice

Original Poster:

498 posts

268 months

Thursday 17th May 2012
quotequote all
So, the prize goes to....

Well several people really.

The fuse was blown and corroded.

Once corrected, however, the alternator still did not produce enough charge - so I suspect the alternator gave up and may have blown the fuse in doing so.

Could I give credit to the guys at Offord Motor, who agreed to see my car and look into it immediately for me, since I was on a deadline? They could not have been more helpful,. including giving me a loan car there and then to take away.

So helpful they are now fitting a new alternator for me, when hopefully I will get back my car. If, of course, they are wrong, I may edit the above wink


Rich