Alternator not charging battery

Alternator is a second hand one from ebay…have replaced the part of loom from starter to alternator as it was manky. Used high rated cable that won't melt.

Tested the voltage over battery when running - 11V.

Voltage at alternator is 11V then actually goes up when ignition is turned off (like it's draining it?) so can someone please confirm it is definitely the alternator at fault? Don't want to buy another and have the same problem. :-(

I have one red/black wire going to my starter and have also added an extra earth from starter to metering head metal part (my car didn't have an earth coming from starter for some reason?) but this has made no difference.

Supposed to be going to Romania on Saturday in it so any help, even to confirm my worst fears about this stupid ebay alternator is appreciated!

It sounds like the alternator. Yeah if the alternator is producing no current, then the voltage will drop slightly with the ignition on (some electrics will be on) and a bit more with the engine running (coil is now working too).

Might just be the regulator pack though.

Alternator is a wearing part, and bulky (–> high postage costs) so secondhand off eBay is uneconomic.

Tell me about it!!! Bought it on the premise is looked good and 'was off a 40K car'- how silly of me now. :-(

Doesn't make any funny noises like my old one did…hmm will try a different regulator on it in the morning methinks.

Can't think of any harm done in changing the piece of loom, have replaced it exactly as it was. Should there be an earth from starter to somewhere? Wondering why my car didn't have one but danj's clipper did. Early/late spec I wonder??

Oh and the fated battery light stays on dimly- another sign of it not charging.

p.s. thanks for the reply, much appreciated.

Battery light staying on - definitely alternator

The earth is achieved through the engine block - if your starter motor turns, the engine must be earthed etc. so don't worry about this.

pull the little blue wire off the alternator and recheck the battery light. if light goes off, fine yes alternator fault. if not, then blue wire or dash fault.

if the light goes off as expected, check/replace the brush pack before you write off the alternator. it held on the back with 2 screws, remove it and check the connections between it and the alternator. round one of the bolt holes is a metal contact ring, make sure that and the alternator mounting face is clean.  there should also ne a metal edge bit which contacts some metal prongs inside the brush pack hole, check those too as above. also look at the brushes to make sure they look good

Hi,

I have a alternator you can try on  if you want. Only downside is that i'm in Darlington, so it maybe a bit of a trek.

TIm.

rubjonny said

make sure that the alternator mounting face is clean.  

what the bit that mounts to the block? Previous owner has painted this, maybe this is the problem?

Trying a different regulator this morning, and got another alternator to try to make sure that is def the problem.

Thanks for the help and offers of help.

that wasnt what i meant but yes that wants to be clean too as the alt earths to the block

what i meant was in the hole where the brush pack sits, one of the bolts connects the ring on the brush pack to the alternator so the mounting there needs to be clean so it makes a good connection

Sorry to hijack this!

If there is a fault somewhere in the blue wire/dash will the alternator still charge?

I have just put a brand new alternator on and it isnt charging! The battery light on the dash doesnt come on at all!

Cheers

Chris

if the blue wire isnt connected no the alternator wont charge properly. sometimes if you rev over 3k they start charging but not always.

if the light wont come on its the blue wire tats disconnected/broken somewhere, or the bulb in dash is blown

Thanks rubjonny, that sounds exactly like my issue!

Muchos appreciation