Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[cd 2.2]

Right I changed the pack on the back of my bosch 100 amp alternator for one from an astra alternator (couldn't be bothered to change the pulley's over and both units are the same apart from this). Shortly after I have done this I have noticed that the battery light shows really dim on the dash until I get the car moving 
I'm going down the line of thought that brings me to an end point of, the replacement second hand pack is also failing 
I can only think that it's that or that the battery isn't too healthy but the alternator is definitely putting out acceptable charge levels during normal use .... Any ideas?

[tidla]

If the pulleys are of different diameters then maybe the "cut in" speed has altered?

[Vamps]

If the pulleys are of different diameters then maybe the "cut in" speed has altered?

+1..........

[terry paget]

What's the voltage at the battery terminals with engine idling? It should be 14.5 volts. Switch on rear screen heater, headlights and flashers and see how much it falls. If it falls below 13 volts all is not well.

[Kevin Wood]

Resistance in the wiring to and from the alternator and battery will do this. Check the crimped connections at the battery terminals and also double check the wiring at the alternator for soundness. You might also need to clean up the areas where the alternator bolts to the engine to achieve a good ground connection.

[Marks DTM Calib]

Also a failed diode in the rectifier will do the same.

[cd 2.2]

If the pulleys are of different diameters then maybe the "cut in" speed has altered?

Pulleys are the same diameter I measured them both  Voltage on idle is 14.2  volts I believe and it never drops below 13 volts, even with full load and all electrics running ... I can always go get another pack (it was only emergency in the first place) but where do I get a brand new one from?

[Kevin Wood]

If the pulleys are of different diameters then maybe the "cut in" speed has altered?

Pulleys are the same diameter I measured them both  Voltage on idle is 14.2  volts I believe and it never drops below 13 volts, even with full load and all electrics running ... I can always go get another pack (it was only emergency in the first place) but where do I get a brand new one from?

Do some diagnostics first.

Measure voltage drop from casing of alternator to battery negative terminal, then B+ terminal of alternator to battery positive terminal, with the engine running and plenty of electrical load. If you get more than a few hundred millivolts, it's a wiring issue. Also check that neither of the battery terminals are getting hot under the same conditions.

Google "Mid Ulster Rotating Electrics" for a decent source of both regulator and rectifier packs.