Iskra alternator AA3346 14V 70A

[Bro]

Subject alternator has B- terminal (having small spade type tag) which is the only terminal not connected to the loom.  I should say there is a heavy cable from the alternator which goes to earth/ battery negative.  The alternator charges batteries fine.

Question is, ought the spade connector B- be also connected permanently to the battery neg or earth (same thing effectively) or to somewhere else or not at all?

[Tony Brooks]

I don't know the alternator but I suspect some misidentification.  A photo please. My guess is that the bade is a radio suppressor terminal that happens to be close to the B- stud.

[Tony Brooks]

I have not been able to identify that alternator number online. It seems there should be anther letter after the AA but none refrences I found showed the terminal end.

[Bro]

On 28/06/2017 at 19:52, Tony Brooks said:

I don't know the alternator but I suspect some misidentification.  A photo please. My guess is that the bade is a radio suppressor terminal that happens to be close to the B- stud.

Apologies Tony for tardy response but have been away some time.

Photo attached which shows the alternator terminal marked 'B-' which seems not connected to anything.  It's positioned just below and to the left of the 'D+' terminal (black/ yellow cable to warning lamp).

Ought this 'B-' terminal be connected to anything? And if not then ought it be insulated?

Alternator is not giving problems, I'm just curious.

[Tony Brooks]

Many alternators that have a B- terminal are actually built as "earth return" inside so although that B- terminal has what looks like an insulating washer/distance piece under it I expect the negative diode plate is making contact with the case inside.

Test this with the engine off by setting a multimeter to beep test and go between the B- and the case. I am sure that you will get a beep indicating continuity.

If that's a 6mm blade its a joke, a 9mm one might just about make some sense.  You could make a negative connection to the stud if you really wanted to but use the same size cable as the B+ side.

[Chewbacka]

3 hours ago, Tony Brooks said:

Many alternators that have a B- terminal are actually built as "earth return" inside so although that B- terminal has what looks like an insulating washer/distance piece under it I expect the negative diode plate is making contact with the case inside.

Test this with the engine off by setting a multimeter to beep test and go between the B- and the case. I am sure that you will get a beep indicating continuity.

If that's a 6mm blade its a joke, a 9mm one might just about make some sense.  You could make a negative connection to the stud if you really wanted to but use the same size cable as the B+ side.

I think you are correct.  I just had a look at the Iskra catalogue and it seems to show that the B- terminal is connected to the alternator frame.

http://www.iskra-agv.cz/us/pdf/alternators.pdf

Edited July 4, 2017 by Chewbacka

[Bro]

Thank you gentlemen.  Seems there is nothing for me to worry about and I don't even have to insulate the terminal.