Alternator not charging

[Mike C]

My trusty old alternator recently suffered from a cracked case, so I replaced with an unused one sold on this site. I've no doubt the replacement is in fine working order but ever since, I've suffered from flat batteries.

 

On start up, the red ign light stays on until I blip the throttle. With headlights on, if I increase the reves, they glow brighter. Is this a sure fire way of confirming that tyhe alternator is working and charging the battery.

 

I've also noticed that the ign light flickers on sometimes when revs return to idle.

 

Any ideas???

 

 

Mike C

K9 JPE

[Sheds Moderator]

Get a voltmeter/multitester and check battery voltage with the engine running. It should be 12.5 or better engine off and 14V or better with it running at 2000rpm.

 

Try checking the battery voltage engine off then putting on the lights. It should hold 11V or better for a minute or so. If not the battery is dead.

 

A dead battery will sink to under 9V very quickly with the lights on.

[Irrelevant]

With headlights on, if I increase the revs, they glow brighter. Is this a sure fire way of confirming that the alternator is working and charging the battery.

Well it shows the power being produced by the alternator increases with engine revs.....As far as charging the battery goes, well it doesn't confirm that. If power is being produced but not being stored by the battery I'd suspect the battery (assuming the wiring is OK).

 

I guess BOSS' checks will tell you if you've been sold a dodgy alternator or not

[bigsmellydaddy]

What engine ?

Mine did the same - changed it for a brand new Lucas (now Hella) unit for 35 quid - light off on tickover and no probs.

[Mike C]

thanks all for the replies. I'll try and do some tests tonight.

 

It's a vx 2.0 by the way.

 

ta

 

 

Mike C

K9 JPE