Summer charge resistance ohms value?

[Tattybogle]

Does anyone know the value of the summer charge rate wire resistor in the little box atop the dynamo in a 1932 RN?

Many thanks in advance.

[John Cornforth]

For the later Ruby, I believe the resistor in the bulkhead CFR unit is 3 ohms.  I would expect a similar value in the earlier style unit mounted atop the dynamo.  It roughly halves the field current when in circuit, and will dissipate a few watts.  The value isn't critical, a commercial type of 3.3 ohms rated at say 5 or 10 watts would be worth a try.

[Tattybogle]

For the later Ruby, I believe the resistor in the bulkhead CFR unit is 3 ohms.  I would expect a similar value in the earlier style unit mounted atop the dynamo.  It roughly halves the field current when in circuit, and will dissipate a few watts.  The value isn't critical, a commercial type of 3.3 ohms rated at say 5 or 10 watts would be worth a try.

Many thanks for your helpful reply, John.

[peter burton]

About £4 on fleabay are 1.5 ohm ballast resistors as fitted to MGB's. On both my Chummy and RP these bring the half charge down to a couple of amps charge rate, just fine for summer jaunts.
All the best,
Peter.

[Tattybogle]

About £4 on fleabay are 1.5 ohm ballast resistors as fitted to MGB's. On both my Chummy and RP these bring the half charge down to a couple of amps charge rate, just fine for summer jaunts.
All the best,
Peter.

Thanks, Peter, that is very helpful.  Am I right in assuming that you connect this in series with the existing wire resistance?

[peter burton]

PM sent.

[bob46320]

I use a 1.0 ohm on my '32 RN.  The wire wound resistor around the ign light is 15 - 20 ohm.
BobH

[Bill Dixon]

I use a 1.0 ohm on my '32 RN.  The wire wound resistor around the ign light is 15 - 20 ohm.
BobH

On my RP I use a 22ohm 0.6 watt resistor to replace the wire wound resistance wire on the ingnition warning lamp, the value of the series resistance mounted on the under side of the CFR cutout is 3 ohm.

Hope this helps.
Bill in Lincoln.