Alternator issues

[Greg.w]

Hi folks

At the very end of building a track 182 and it's just 1 thing after another just now! Got so close to taking it for its first run on the road tonight and now I think the alternator has packed up!

So the car was sitting idling while I was clearing some tools away and all of a sudden it cut out. Tried to restart it but wouldn't turn over. Checked the battery and was around 11/11.5 volts.

Put a jumper pack on it and got it started fine. Tested the battery while the car was running and was only around 11.5/12 volts, dropping all the time instead of the 14.5 ish I would have expected.

So sounds like my alternator is knackered? I tested at the alternator between the main live connection and an engine bay earth and was getting the same reading as the battery, 12 volts ish dropping all the time. Assuming I am testing this correctly?

I can't confirm 100% but I'm nearly sure the battery light was not illumited on the dash board. I checked the other small connector with the single wire (assume this turns on the dash light), connection seemed fine.

Before I bite the bullet and get an alternator, anything else I should check first?

Just for context the weather has been getting in to the alternator area for a little while due to having the front end off the car, it's also stamped 2007 so has done a good turn to say the least!

Thanks
Greg

 

[bashracing]

Check you have battery voltage down the small wire to the alternator with the engine running,

If you do the alternator's toast and needs replacing

If no voltage you have a wiring issue on that wire.

 

[Greg.w]

Check you have battery voltage down the small wire to the alternator with the engine running,

If you do the alternator's toast and needs replacing

If no voltage you have a wiring issue on that wire.

Brilliant thanks mate

 

[Greg.w]

Also worth noting that I have moved the battery to the boot recently. I extended the positive to the boot but grounded the battery in the boot near a seat belt mount. It's in the back of my mind that this could be the issue but all connections check out ok

 

[Mr Underhill]

Also worth noting that I have moved the battery to the boot recently. I extended the positive to the boot but grounded the battery in the boot near a seat belt mount. It's in the back of my mind that this could be the issue but all connections check out ok

I bought a battery relocation kit from Demon Tweeks when I did mine. So have you used the correct cable?

Extending the length of cable increases resistance, which can affect voltage.

There’s a formula for this but essentially you’re just introducing thicker cable. And to take the guesswork out of that, it’s just easier to buy a kit.

Mine’s behind the back of the passenger seat in a cage (for added safety). Any reason why you need to go to the boot?

 

[Greg.w]

I bought a battery relocation kit from Demon Tweeks when I did mine. So have you used the correct cable?

Extending the length of cable increases resistance, which can affect voltage.

There’s a formula for this but essentially you’re just introducing thicker cable. And to take the guesswork out of that, it’s just easier to buy a kit.

Mine’s behind the back of the passenger seat in a cage (for added safety). Any reason why you need to go to the boot?

The only kits I could see were pretty crap Ebay jobs. The cable I got is multi stand 25mm2 cable. Shouldnt be an issue with that. Cable wasn't getting hot either and both the voltages at the battery and alternator were identical so couldn't be voltage drop (alternator would have been reading correctly, battery would have been low).

I went for the boot just for weight distribution really. Hardly makes a difference but for the sake of 1m of cable I just put it in the boot.

 

[Greg.w]

It's also fused correctly with proper hydraulic crimped ring terminals etc.

 

[Greg.w]

Got an alternator fitted and it's now charging about 13.8 to 14.2 from a quick 2 minute test idle tonight. Checked all the earth's etc on the battery where it's located now and all are perfect from my testing.

It's just a cheapo alternator (starline) from Euros. Fit is good and charging seems to be OK for now. 2 years warranty and was £67 (110a version) (also didn't have to give my original back as exchange so can get it rebuilt if need be). Probably won't last as long as an original renault (valeo I believe) but seems decent quality for anyone interested.

Thanks for everyone's replies!