I have a 1972 Clubman with Lucas ACR15 internally regulated alternator.

Recently i left the car in a garage for 3 weeks and the battery went dead flat.

The only non standard item drawing current is a cd player which has a yellow "hot all the time" wire to power the cd player clock, memory etc.

I suspected some parasite current drain and found a 40-50mA discharge. Taking the fuses out was unhelpful so I disconnected the power lead from the alternator. Battery drain dropped to 8mA, a more realistic figure for a cd clock.

So I surmise that there is an internal fault in the alternator.

Does anyone have experience of such things? Is it a crook diode? Is there an easy fix?

Auster3

It could well be a diode failing in the regulator or a transistor . The internal regulators for the 15 / 16 ac are becoming hard to get. I replaced the whole alternator with a 17 acr which also has the benefit of greater output as well as readily available parts.

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Cheers Dave.

I had the same problem, a NOS UK made alternator I bought 20 years ago fixed it.
New alternators are so cheap it's not worth fixing old, unless it's a real S...

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.