Alternator upgrade.

[Johnny The Fox]

Decided whilst I was mucking about changing the distributor I would upgrade my existing alternator on my V8 for a unit with 65amps output.
Duly googled and up came a listing on eBay for a unit that was a straight replacement for the Lucas ACR.
Bought it, fitted it, worked great for 2 hours then, the ignition warning lamp would fail to illuminate when the ignition switch was turned on. Then it came on and wouldn’t go out.
Putting a voltmeter across the battery terminals revealed battery voltage 12V when running and a drop to 11,3 V when the engine was revved.
So any ideas on what went wrong, oh I refitted the original alternator and all is fine. Needless to say the unit will be returned to vendor !

 

[DaveRover3500s]

Hi John. Defo dodgy unit I’d say. Hate to say. Lots of ify ones on fleabay. I know it’s likely well known but in case- the alternators are ‘sided’… well it seems they are…. But actually they can be altered with little trouble. The 3 long bolts that connect rear and front parts and hold together can be undone and the front turned then bolted back up - changes it round to opposite side to what it was. So if you see a good 65amp (that’s what I have fitted) but it’s not right side for Rover it can be easily changed!

Dave

 

[jp928]

I find a voltage display is a lot more useful than an ammeter in assessing battery & alternator health, so I have a little unit tucked up under the dash cap on the left. With a healthy alternator you should see ~ 14.5V immediately after starting, tapering down to 14.1v as the battery comes back up to full. Less than 13.8v can be a sign the alternator is weakening, or there is a high resistance somewhere, probably a ground.

It looks bright here as the car was under a cover and dark. In natural light its fine.

 

[DaveRover3500s]

Yes I agree re voltage. I got a little voltage display that plugs into cigar lighter for about £3 off eBay and I just plug it in - very handy and accurate when checked with voltmeter! Reassuring!

Dave