Polarity

[Col.Coleman]

Need help please Oh wise ones.

Upon reading the online manual, it tells me that all series 1's were positive earth. Also that the fuel sender, wipers, horn and something else are the only things fused, the rest is not.

What happens if you hook up a battery negative earth.

I only ask this as I have done just that and got the vehicle to run. nothing much else works though.

I had a bit of a head scratch looking at the terminal ends to see which one was bigger than the other to give me the clue to which one was earth(normally the smaller one), but they were both roughly about the same size. I hooked up a near dead battery, to limit current, and the fuel pump turned in the right direction, as did the starter.

Now in my way of thinking, if you reversed the current in such simple deveces the should run in the oppisite direction, so it would seem to me to be a negative earth machine.

I'm too scared to hook the battery up in reverse and see what happens.

I did get some smoke from the headlight circuit, but the wiring is not the best. And the generator is working, lifting the votage to over 13.5 volts, but this should probably still do this reversed polarity.

HELP

CC

[Aaron IIA]

On a vehicle such as this that has no transistors, (still has SU fuel pump and generator) you can put the battery in which ever polarity you wish. The only difference is the direction of the amp gauge. You will get a slight improvement in the effieiency of the coil if you put it's polarity correct, (the polarity of the coil, not the vehicle) but most people would not notice this. The starter motor generator and windscreen wipers have wire wound fields, so are not polarity sensitive.

The vehicle would have originally been positive earth. If you now have a solid state modern electronic fuel pump, you must get the polarity of the fuel pump correct, or it will break. You can still do this with positive earth by connecting the red wire to the chassis instead of the black wire. If you want to fit an alternator, you need negative earth. In theory, you could purchase a positive earth alternator, but I have never seen one. If available, they would be expensive.

Aaron.

[p38arover]

The generator may need flashing. They rely on residual magnetism to start charging.

[series1buff]

Hi Col

the advice so far is good and sound . Aarons explanation says it all.

If you do swap polarity , you need to change around the ammeter connections , otherwise it will show a negative charge on the dial. From what you said , it is charging OK at 13+ volts .. so it may have already been swapped over to NEG ground by a previous owner .

You won't damage anything by reversing polarity but:

The generator has iron cores that the 2 field coils are wound over .. a small bit of residual magnetism is in those cores, it provides a weak 'start up' field for the armature .. otherwise the gen wouldn't do anything .

If you change cars ground polarity.. you need to re-polarise the cores in generator to the correct polarity . Most people use a jumper wire from the ungrounded battery post to the field terminal on the generator .. you just touch it for a fraction of a second .

On the fuses , yes its a worry . When I wired up my car, I used a modern fuse bank, with seperate fuses on everything . I think you can buy replacement looms in the original style , cotton, very expensive though. . But for practicality .. I used modern PVC wires .. Smoking wires are a worry = panic time.

Hope this helps

Mike

[Col.Coleman]

Thanks all.

The ammemeter is not moving at the moment anyhow. I will reverse things around and see what happens.

The fuel pump is a nikki and I got about 4 of them with the cars, and the make that nice tick, tick sound, so I think they are the original type unit.

I found the main fuse, busted. Will see what works when I replace it. Also found one on the regulator top right and place for another top left.

An open bank of fuses has been fitted below, looks hooked up to the indicator circuit that was fitted at some time. Have to trace it all when I can.

I am supposed to be tidying and making room, but I keep getting side tracked

CC