luxeon 3w voltage help for an idiot!

I really am an electrical numpty, so some gentle guidance please!! I have searched and probably found the answer but it all gets lost in the techy stuff.

I am building a 3 x 3w luxeon bike light. I have a 13.4v 4.2 a/h Nimh pack to power it, I have 3 SYOK bins at the minute. What voltage do I need to run them in series/parallel. What sort of driver/recommendations please. If those luxeons won't work what BIN do I need to go to?

Any other help in idiot speak most appreciated!!! Thanks mark in the UK

It seems like you got an 11x cell NiMh pack. With that configuration I would recommend you use a george's nFlex and drive these 3x3W SY0K in series.

You'll get a whopping bright & durable light that will last 4hrs+.

George sent me this reply in an email as I thought Nflex looked the right thing:

********************************************************** K binned are marginal to run 3 from 13.2V (nominal 11 pack I assume). If you could source some TxxH you would have a much better setup.

Anyhow, the numbers go like this:

K bin (3.75V - assume worst case) x 3 = 11.25V

Once the nimhs are run down a bit they'll be around 1.1V x 11 = 12.1V.

To drive 1A to the load, nFlex needs close to 2V of input voltage greater than Vf. That means you would need 11.25+2 = 13.25V and you barely have that with the batteries fresh off the charger. So, you either need H bin Luxeons or more batteries in your pack.
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does that make sense to you? lost me, would the Nflex work with my setup? and woiuld i wire them in series, any idea what sort of runtime I would get? sorry for all the questions....Mark