red warning light

[briandoc]

My Sterling "alternator power booster unit" is showing a red warning light "high voltage trip". The 2 green lights for "ignition on" and "boost charge on" are also illuminated.
I would appreciate any advice on whether this is a fault and, if so, where I should look for the problem.

Brian Heather

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[LadyInBed]

Whats the voltage across the battery?
1 at rest
2 on load
3 When alternator is charging

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[briandoc]

Thanks - I will take a voltmeter with me on Monday and take the measurements you suggest

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[HaraldS]

Assuming theregulator is still OK, it would indicate that when stated it switched into boost-charge mode, but quickly reached the cut-out voltage, which is around 16V I think. It could mean:

A bad connection between alternator and battery, or a dead battery. Off course the third alternative is that the regulator is broken.

If the voltage sense line of the sterling regulator is connected directly to the battery, like is recommened, you could rule out the positive connection between battery and alternator.

It would then most likely be some corrosion on the minus cable, however if your engine starts just fine, at least the connection from engine chassis to the starter battery must be ok. Still you may have separate service batteries and the connection there might be bad.

Measuring is difficult, because a shut-down happens so quickly, that you can't catch it unless you have a recording meter.

You could by means of a cable with crokodile clips, put full voltage (minus or plus, depending on how your alternator is excited) onto the filed coil and with a half way discharged battery now charge unregulated and measure:

Voltage at battery: if more than 15V your battery is bad.
If less take next step and measure voltage at the alternators Bat+ and Bat-.
If that is higher than 15V and more than 1V higher than what you measured on the battery, then you have a bad connection.

If it seems to charge happily, with a voltage between 13 and 15 V, you will need to check you regulator wireing, and if all that seems fine, send the regulator in for checking.

Ah, before you do the manual exciting of the alternator, pull out that little car type fuse from the Sterling regulator, the one that gets pluged in different depending on negative or positive excitement. Taking the fuse out separates the field coil entirely from the regulator.


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[briandoc]

cleaned up and tightened the battery negative connection - problem sems to be fixed - thanks for your halp and advice

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