1/2 Charge Resistor - Advice Please.

[Ian McGowan]

Hi John, Using the names used on your diagram here,  one side of the resistor to the POS Dynamo terminal (+D), the other side of the resistor to the Dynamo SHUNT (SH) terminal; both located on the rear of the ammeter.

[John P]

I've just wired it as suggested but although on full charge with nothing turned on the ammeter shows approximately 8 amps charge, in the 1/2 charge position there's virtually no charge although no discharge either.

This was done on the drive at reasonable revs but obviously it's not the same as if it was being driven.

[Reckless Rat]

Sounds ok to me.

[Bob Culver]

That wiring diagram contrives to make something very simple quite obscure, even for those with elctrical experience. Has anyone redrawn a clear version, as John Cornforth has for the later cars?
I presume it applies to the dyns originally with inernal resistor but there is no hint of it.

[Bob Culver]

Is the coil drawing an unusually high current?. The field internal resistance seems to be about 1.5 ohm. Trebling total reis reduces field current to 1/3 and, altho not necessarily linear, output probably simialr. So if 2 amp running coil current 10 amp gross reduces to 3.3 and with coil current subtracted, almost no net output
If the resistance winding is unenclosed and not insulated could short a few turns with a wrap.

[Renaud]

That wiring diagram contrives to make something very simple quite obscure, even for those with elctrical experience.

Ha ha! Agreed Bob!

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I use a little Non to expensive electric box of tricks made by Ron Bailey a member of the PWA7C with instruction from him slight modifications are made to the wiring of the dynamo and the 3rd brush is removed. This allows for better charging of the battery with no requirement for Summer/Winter switching.  I have had this for the last 6 years without any problems.  The other benefit is that it charges faster and is kinder to the battery as it shuts off charge completely when the battery is full of charge

John Mason

Hi John,
I'd be interested to know more about that box please. Any link?

[Bob Culver]

Hi Renaud
I have never had cause to more than glance at the diagram. The more I look the worse it gets! It would be easier to fathom from the actual switch. I cannot understand why it is so obscure. Perhaps as today they wanted to channel all diagnostics to the agents!
All the contacts on the ign/dyn switch are shown joined?? If the fuse (star) blows the dyn output seems connectd to the field and nothing else, a very undesirable state likely to burn out the field?

[John Mason]

Renault I have sent you a PM.

John Mason.

[David Cochrane]

I have just fitted a C35M dynamo to the RP and put a 3.3Ω resistor across the terminals of the dynamo, where it fits very neatly beside the terminal block under the connecting wires. I get 10-12A on full charge and 1-2A on 'half'-charge. Ideal.