Simple test of hub dynamo

[Sweep]

Yes clearly a dynohub theme at the mo, but this is a specific narrow question.

I bought a cheap dynohub wheel from Decathlon to do some testing with power generation to a powerbank (no need for lights).

The hub is a Shimano DH C3000 3NQR

In doing some initial tinkering I am worried that I may have damaged it.

Is there a simple way to check that it is working?

ie just the Dynamo - I do have an ewerk power convertor kindly given to me by someone on here which I intend to use to link to a powerbank.

But since I gather that device in itself can be a bit complicated I would like to take things one step at a time.

ie - see if the dynohub itself is working.

If it is will start connecting/testing other stuff.

Seem to remember that I may have read about a "spark test" somewhere.

Look forward to some advice - please note that I am an electrical ignoramus - can wire a plug, that's about it.

[rjb]

If you spin the hub it should be relatively free, just a bit of cogging. Short the terminals it should be a lot more difficult to spin. You could check if you get a spark across the terminals as well by momentarily shorting across whilst spinning the hub.

[Brucey]

put a dead short across the terminals. The result should be much more drag than normal.

cheers

[Sweep]

If you spin the hub it should be relatively free, just a bit of cogging. Short the terminals it should be a lot more difficult to spin. You could check if you get a spark across the terminals as well by momentarily shorting across whilst spinning the hub.

Thanks for reply rjb but as I said I'm an electrical ignoramus and I stress it's the electrical side of the hub I want to test, not mechanical, basically as I have a concern I may have bust a connection.

By "short" I assume you mean make a direct connection between the two terminals.*

What would you use do do this or to try to generate a spark?

Would something laid across them, but not necessarily touching them, work? Like a screwdriver or a long allen key?

Or do I need to find some suitable wire which will actually touch both contacts?

*I assume that this shorting would do no damage since no sensitive device of any sort is connected in the circuit?

PS - excuse my paranoia - can you elaborate on your final wink?

Something I shouldn't really do for some reason?

[Sweep]

put a dead short across the terminals. The result should be much more drag than normal.

cheers

Apologies ditto for ignorance.

Can you explain what you mean by a DEAD short Brucey?

How would you suggest I do this/using what?

[Brucey]

dead short = no electrical resistance

use a length of wire, paperclip, w.h.y.

cheers

[Sweep]

dead short = no electrical resistance

use a length of wire, paperclip, w.h.y.

cheers

sorry brucey (testing your patience I know)
what does
w.h.y

mean?

[Brucey]

what
have
you

[backnotes]

As above - short the terminals and it should get harder to turn. Pictures of Shimano hubs suggest there are two holes in a terminal block and if you bend a U out of a paper clip and put a leg in each hole so it wedges in, you might not need 3 hands to spin the wheel, hold the axle and short the terminals at the same time.

The other obvious test is to stick a dynamo light across the terminals and watch for it flickering as you turn the wheel, or a 6v bulb with flying leads.

Then I'd keep an eye on this evolving thread viewtopic.php?f=5&t=138977 when you get onto the next stage the project!

[Sweep]

Many thanks folks for the usual swift great advice.
Applied a bent paperclip to the contacts (didn't bother doing via the clip-on plug) and got not only the reassuring extra drag but some sparks as well.
I folded some insulation tape over a bit of the clip and held it there with some pincers.
Wasn't sure if that step was necessary to achieve proper result but as I said I know nothing about electricity and power generation.
Thanks again - doubtless now onto further complications