Joined: Apr 2018 Posts: 507 Threads: 129
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Location: Staffordshire
Car type: Ruby mk 2
Some of you will remember all the trouble with my Ruby Dynamo.
After reporting too much end float I had the good advice to reduce the amount.
But after rebuilding the unit I could not get it to generate.
I was sure it was rebuilt exactly the same so was puzzled
After repolarising it was OK
However it appears it will light a 12v / 21w bulb BUT NOT a 6v bulb ??
Any ideas why.
PS Sorry to keep resurrecting this issue.
Happy new year to everyone
Joined: Apr 2018 Posts: 507 Threads: 129
Reputation:
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Location: Staffordshire
Car type: Ruby mk 2
Thanks for the thought
Both bulbs light on a battery
Joined: Aug 2017 Posts: 2,748 Threads: 31
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Location: Auckland, NZ
If you are starting with the bulb connected, try running the dynamo (with field connected), at modest revs before attaching the bulb. A large low resis cold bulb my keep the sytem volts down so cannot start.
On the late 4 pole dyns with internal field resistor, if requird to run disconnected from the car system (and hence battery) the only suire way to nobble the dyn is to fully earth field and output. With a large cold bulb you may have a situation analogous.
Joined: Apr 2018 Posts: 507 Threads: 129
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Location: Staffordshire
Car type: Ruby mk 2
Thanks Bob
I will give it a try in the morning
Joined: Aug 2017 Posts: 612 Threads: 19
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Location: Hampshire UK
Hi Tiger
A common test method is to strap the Field input to the Dynamo output. However, without a battery connected to cap the voltage at 6 to 7 volts, the output can rise to high levels as the dynamo speed is raised. This risks cooking the field coils if you keep going for too long.
As Bob hints, the problem with a bulb-only load is that a cold bulb has a very low resistance compared to when it's burning bright. The dynamo output may never build up and get "off the ground"
An alternative method is to run the field completely independently from a 6 volt battery. It will draw 2 or 3 amps. I suggest the load on the Dynamo output is one or more 6V bulbs in parallel, with a total rated wattage of say 30 to 60 watts. This will give a realistic load for testing.
Joined: Apr 2018 Posts: 507 Threads: 129
Reputation:
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Location: Staffordshire
Car type: Ruby mk 2
John
Many thanks for your help.
As usual a comprehensive answer .
I am working towards getting my Ruby roadworthy this spring.
This impart due to much help from yourself and other seveners
Thanks again to all.
Regards
Tim
