• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.

    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

TR5/TR250 TR250 Alternator Warning Light

Well, here's a status update:

The new regulator arrived from Moss. Turns out that other than the foil decal they have attached to the cover, admonishing one to be careful about polarity, the unit is identical to what I have previously purchased from BPNW. Only difference was that Moss' regulator was more than TWICE as expensive. Lesson learned on that one...

So I carefully connected up the new, new regulator and ... no change. Just as before, the alternator warning stays lit with the key out and engine off. The light turns off when the key is turned to the first position and stays off when I start the engine. So, I am convinced the problem does NOT reside with the regulator.

One other thing I tried was to disconnect the black wire connected to the "-" terminal on the regulator and connect a length of wire I made up that I could connect to a good visable ground. Theory being that I am not sure where the other end of the black wire actually grounds, as the wire dissappears into the harness within a few inches after leaving the regulator. This resulted in no change.

The only remedy that seems to actually work is to disconnect the brown wire that connects to the B+ (or unmarked terminal) on the regulator. With this wire disconnected, the alternator light no longer stays lit with the key out/engine off, lights when the key is in the first position, and turns off a second or so after the engine is running.

I think the charge the battery receives from the alternator comes through the heavy NW wire connected to the "+" terminal on the alternator, which leads diretly to the ammeter and then to the battery.

If this is correct, am I doing any harm by not having this N wire at the "B+" regulator terminal connected?

Yours truly... confused and frustrated!
 
RagTopMan said:
If this is correct, am I doing any harm by not having this N wire at the "B+" regulator terminal connected?

The issue would be the same as I mentioned before. If the regulator does not limit the output voltage of the alternator, it will severely overcharge the battery (once the battery becomes fully charged, of course). This will result in the battery throwing droplets of acid out the vents, which will attack whatever they come in contact with; along with an explosive mixture of hydrogen and oxygen that can potentially do some serious damage if it happens to find a source of ignition. (Trust me, battery explosions are no fun at all.)

It will also seriously shorten the life of the battery.

But I think it would be worth checking (in some fashion) whether the regulator is regulating or not. I have a feeling that it will, in fact, work perfectly without that wire.
 
Back
Top