Lucas AC11 Alternator with Bosch Regulator
Oct 26, 2020 9:48:30 GMT
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Phil Nottingham likes this
Post by thomashb on Oct 26, 2020 9:48:30 GMT
Hello,
New owner of a P5B Coupe with some odd charging circuit behaviour.
Just recently in June, previous owner had the Lucas AC11 alternator rebuilt and a Bosch RE55 regulator installed where the Lucas 4TR used to be. Is this a common modification? I have searched the forum for mentions of the Bosch regulator but didn’t find anything.
The 3AW warning light relay is still present, as well as the Lucas 6RA relay.
Presently I am seeing only 12.1v at the battery at idle and under medium load I only see 12.8v. This is consistent when testing the voltage at the battery wire output of the alternator itself.
If we take the recent receipts from the auto electrician at face value, the alternator and regulator should both be performing fine.
I therefore have two questions for the brains trust:
1. Would a faulty 3AW or 6RA relay cause low voltage like this?
2. I am also unsure if the ignition light behaviour is normal. When I turn the key to the On position but do not crank and start the engine, the ignition light comes on for two or three seconds and then goes out if I don’t start the engine.
If I turn the key to the On position and immediately crank and start the engine, the light stays on throughout the cranking process and stays on a little longer after the engine fires up and goes out in the normal way once the revs have picked up and the alternator is spinning nice and fast. Under both scenarios, the voltage at the battery is the same.
Grateful for any answers to these questions you come up with or any advice you might have about removing the Lucas 3AW and 6RA altogether.
Cheers,
Tom.
New owner of a P5B Coupe with some odd charging circuit behaviour.
Just recently in June, previous owner had the Lucas AC11 alternator rebuilt and a Bosch RE55 regulator installed where the Lucas 4TR used to be. Is this a common modification? I have searched the forum for mentions of the Bosch regulator but didn’t find anything.
The 3AW warning light relay is still present, as well as the Lucas 6RA relay.
Presently I am seeing only 12.1v at the battery at idle and under medium load I only see 12.8v. This is consistent when testing the voltage at the battery wire output of the alternator itself.
If we take the recent receipts from the auto electrician at face value, the alternator and regulator should both be performing fine.
I therefore have two questions for the brains trust:
1. Would a faulty 3AW or 6RA relay cause low voltage like this?
2. I am also unsure if the ignition light behaviour is normal. When I turn the key to the On position but do not crank and start the engine, the ignition light comes on for two or three seconds and then goes out if I don’t start the engine.
If I turn the key to the On position and immediately crank and start the engine, the light stays on throughout the cranking process and stays on a little longer after the engine fires up and goes out in the normal way once the revs have picked up and the alternator is spinning nice and fast. Under both scenarios, the voltage at the battery is the same.
Grateful for any answers to these questions you come up with or any advice you might have about removing the Lucas 3AW and 6RA altogether.
Cheers,
Tom.
