Cree R2 output at different votages

Yoda4561 said:

Those sorts of modules "should" be about the same brightness between 4 and 18 volts, so instead of 4x rcr123 I would run 2x17670 or 2x18650 for the huge increase in capacity.

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blueskybob said:

I picked up a Cree R2 from Dealextreme that is said to have a voltage handling range of 3.7 to 18 volts. But from what I hear anything over 14 will harm it. I have it in a tube with 4 CR123 at 3.0 v (12 volts) and it is nice an bright. Better that the incan that came with it. If I put 4 CR123r at 3.7 volts I will push it over 14. Will this be a big opps?!

Wondering if there is a table showing the output at various voltages or should I just do the old empirical eye test by using dummy batteries to fill in. Thinking of putting a smaller tube on it. Maybe one that will hold apx 2 or 3 CR123 batteries or someting simliar.

3 CR123 3.0 v (9volts) versus 3 CR123r 3.7 v (11.1 volts) versus 2 CR123r 3.7 v (7.4 volts)

Thanks

Bob

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LumenHound said:

You have the single mode R2 drop-in?
Higher input voltages just make it run hotter. Don't go there.
If you read through all of the 45 reviews for the sku # 11836 left by buyers you'll find the info you are looking for.

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Justin Case said:

I found an hot spot lux increase of about 15% when going from 2xSF123A to 2xAW17670 in one of my Cree R2 drop-ins.

Supposedly the single mode DX R2 (I assume we are talking about the DX11836) uses the same driver as the DX6090. That driver has been well-characterized on CPF, for example here.

As the data shows, for 2xSF123A running at about 5V under load, the drive current is just under 0.9A. For 2xAW17670 running at about 7.4V under load, drive current is at the max of 0.96A. There does not appear to be any additional drive current increase at higher input voltages, so you aren't going to get any more lumens out of the LED by using 4xLi-ion or 4xLi primary. However, it doesn't look like you will suffer from any additional decrease in driver efficiency either. As Vin goes up, Iin goes down and PowerIn appears to be relatively constant at about 4.5W-4.7W. Power out also tops out at about 3.2W, so efficiency looks like it also plateaus at just under 70%.

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