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This dynamo business is beginning to get on my nerves!

I have now got the dynamo back from the specialist who has made a nice job if refurbishing it. He demonstrated it on the test bed (with 12v trough the field coils) producing 20 volts!!

Now heres the rub. This test was done with the shaft rotating clockwise when viewed from the commutator end but I was convinced that it actually runs anti-clockwise when on the car. He demonstrated that this cant be the case and to prove it, he spun it anticlockwise and it produced nothing.

Now its on the car and I am convinced that it does actually run anticlockwise and sure enough there is no action.

I should say that the car is a 1930 7-45 but the dynamo is actually an Owen Dyneto type CL1005 from a later 9th series car.

Please dont tell me that the later units ran the other way??

Help!!!!!!

Please dont tell me that the later units ran the other way??

OK, I won't. They all rotate the same direction. And I assume you meant it produced 20 amps, not 20 volts?

Output of the O-D CD-865 and CL-1005 was 18 amps and max 8 volts at 1400-1500 rpm.

Thanks Dave.

no I did mean 20 volts !!! This was apparently because he tested it with a 12v supply...?

I'm determined to get this one sorted without referring to an auto electrician.

I'm going to sit in a darkened room and think some more.....

I'm determined to get this one sorted without referring to an auto electrician. I'm going to sit in a darkened room and think some more.....

That's the spirit!!

" he spun it anticlockwise and it produced nothing."

I assume that the regulator was connected during the test???

As for the voltage at 20 volts it depends on how fast he was turning the generator. Just about ANY automotive or lite truck generator (6v OR 12v) will produce as high as 80 to 90 volts DC when spun upwards of 3000 (engine) rpm which equates to someting a little higher than 3000 generator rpm.((Edit: 80 - 90v WITH THE REGULATOR ELIMINATED FROM THE CIRCUIT)

As for the generator not producing when turning opposite direction i don;t think so unless a regulator was placed in the circuit.


**** DO THE GENERATOR SERVICE test as OUtlined in the manual.
The manual should indicate ELEMINATING the regulaotr from the circuit and testing the generator as ISOLATED from the rest of the car while running. ******

Let me repeat that to determine if the genrator is good or bad IT MUST BE TESTED AS ISOLATED from the rest of the cars electrical system while running. NO REGULATOR connected to it during the test.


EDIT: IF the generator tests out ok using the test outlined in the manual then try a different regulator.

Do a Google search on (IIRC) "type 1" or maybe it's "type A" regulators VS "type 2" or "type B".

But first the generator must be confirmed as a stand alone unit.

I believe the most conventional way of describing rotation is looking at it from the pulley end so CW in that scenario. If the commutator on that generator is at the back end like most other generators, then I would have to agree that looking from the back or commutator end, rotation would be anti or counter-clockwise. Looking at the sprockets, with a direct chain drive the the generator can't help but go the same direction as the motor at slightly faster rpm than engine.

Not that familiar with the third brush systems, but on conventional generators if the field is grounded directly instead of thru the resistors, voltage can go very high. I believe the third brush types rely to a great extent on system load to "regulate" do they not. No load equals high volts which is why you hear tales of blown bulbs when something is disconnected improperly.

I agree HH. Running a generator w/o the resistance of the battery in the loop will send the voltage sky-high and blow whatever bulbs are activated. Can't say I've ever tested a generator the way PackardV8 describes.

PS - there is what appears to be an early 30s used O-D cutout and generator control Type 21262 on eBay as I write this. Item# is 110669704418. Reserve is $300.

YEs. Good point about the battery. I should have indicated to test the generator as isolated from the rest of the electrical system EXCEPT the battery. Does the Packard service manual for this model of Packard not cover the test procedure for the generator?????

Page 42 PACKARD SHOP MANUAL - 1937 SUPER-EIGHT (CONDENSED shop manual version):

"Maximum output 26 amps @ 1650 rpm REGULATOR DISCONNECTED and FIELD TERMINAL GROUNDED"

Note that it indicates to DISconnect regulator and also warns "not to run the generator on open circuit" which i assume means not to operate it under regular service that way.

The more detailed shop manual should give more explicit and detailed instructions to test the generator as UNregulated. If it doesn;t i would be most surprised.

BTW, i have been running a Delco 6 v generator with field grounded to the generator frame now for nearly 20 years and over 650 hrs (about = 30K speedo mileage) with no problems whatsoever. I don;t recommend it. But for test purposes it is generally accepted shop procedure for testing purposes and outlined in most service manuals.

I'd just like to know if the owner of this car has performed such a test???

Thanks guys for your valuable insights.

I am slowly learning the finer details of the 3 brush dynamo (infact I get it 100%) and the regulator/cut out (about 60%).

It is sometimes confusing as there is a lot of seemingly authoritative advice on the interwebs which is actually not properly thought out or just plain wrong. Commonly terms are confused - current / charge / volts / field / induction / amps etc seem, to some people, to be freely interchangable!

(Dont worry - I know exactly what each one means unlike some so-called experts)


Now - back to the saga.

This morning I;

1 removed the relay

2 connected voltmeter between the +ve output on the generator and the +ve terminal on the battery (+ve grounded!) - 0 volts

3 Started the engine 0 volts

4 Connected the field wire on the generator to the -ve battery terminal with a jump lead - 14 volts !!

5 Increased revs from tickover - 19 volts !!

So the good news is that the generator is working very well indeed. I was confused as to why the voltage was so high but I have now seen OD's post regarding the lack of load from the battery. This was of course connected but the flying lead from the ammeter to the relay was not, hence no current was able to flow to the battery.

So step 1 complete!

I now have to turn my attention to the Bosch regulator / cut out I have. I'll take a look at the one on Ebay as an alternative but there is no reason at all why the one I have should not work - its specification is all but identical to the factory original.

More to follow but, in the meantime, thanks again for your advice.