Hi All,

 

I left the lights on in my Dads car last week and she wouldn't start w/out a jump. I checked the voltage on the battery and its was 7.5v, so I presumed it was knackered, so I installed a new battery today, however while driving the battery light came on!

 

Does this mean that the alternator is faulty? Would a scan with vcds lite find this fault?

 

Cheers

 

 

the battery aint getting a charge 

Cheers.

 

Will run a voltmeter across the battery.

 

Is a 41ah battery adequate  for a Skoda Octavia 1.6  petrol? I ask because the battery that I removed if 55ah.

41A is too weak,the 55A is already on the edge

Just tested the battery. 12.03v while engine off, 11.75v while engine on!

 

The guy who sold me the battery was surprised that it was 41A, but I just went with it.

 

What do you make of the readings above? Or with the wrong battery do they mean anything?

 

Cheers

Whatever the AH capacity of the battery - stop worrying about it, because it is not the problem.

 

The problem you have, as another poster has already pointed out, is that the battery is not being charged by the engine.

 

 

The figures should be: 12.7v to 12.8v with the engine off (tested after a 'drop test' - which means checking it after not having run the car for an hour, then switching on something high-drain like the headlamps or heated rear screen for 60 seconds, then switching off, waiting another couple of minutes, and then testing the voltage).

 

Then when the engine is running at idle, the figures should be between 13.8v and 14.5v. This shows that the alternator is charging the battery correctly.

 

 

 

The problem you have is either a faulty alternator, or a fault in the cabling from the alternator to the battery. These cars are also well-known for having a melt-down of the fusebox and cable assembly which is located on the top of the battery itself.

 

Hope this helps!

the alternator isn;t charging...you ned to fix it

a weak batt will still be charged but much weaker...you have no charge at all

check the fuse box ontop of battery has the fuse gone far left side should be a black cable thats the alternator one 

Thanks All.

 

I checked the fuses located on top of the battery and there in good condition.

 

There is a specialist auto electrics guy close by, hopefully he'll  have a refurbished one in stock.

 

Cheers

Well I took a chance today, needed to get to work, anyway long story short, car stopped at the top of the road outside my house. luckily a friend helped out with a pair of jumper cables.

 

Is there neway handy way to determine if its the alternator or the alternator voltage regulator at fault?

 

Cheers

The voltage regulator is internal of the alternator. 

 

Check you the battery voltage with the engine running. It should be about 14.2 volts.

 

If it's not, check the voltage drop of the main power wire on the alternator to the battery, and the engine earth. Check for 12v after ignition on the small connector block of the alternator.

 

If all you're checks are good, but you're seeing about 12v, replace the alternator. 

he already did that and has no charge

 

Harpoon take a look on the back of the alternator and tell me if is a Bosch or a Valeo

If is a Bosch you can easy buy a new regulator and replace it yourself,is a easy job.These Bosch alternators are well known they can be fixed by new regulators.

 

Cheers!

If it is high mileage and showed signs of being intermittent then it could well be just worn brushes. Cost about £5 or less on *ba* BUT if the brushes are worn down then the bearings won't be far behind so probably better to replace the whole unit. 
There are videos on the net showing how to change brushes on Valeo alternators.

he already did that and has no charge

 

Harpoon take a look on the back of the alternator and tell me if is a Bosch or a Valeo

If is a Bosch you can easy buy a new regulator and replace it yourself,is a easy job.These Bosch alternators are well known they can be fixed by new regulators.

 

Cheers!

Yep it's a Bosch. There is a lot of regulators for sale on *Ba* so this indicates a common problem, so will order one and have a go.

 

Thanks for all the help, I'm sure I'll be back!

here is a DIY to replace the regulator,is simple....good luck!