Luxeon w/2 or 4 NiMHs ?

ikendu

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Is there a Luxeon made to run with 2 or 4 NiMH AAs?

The posts I've been reading on the CMG Reactor seem to say that I won't really be happy with it unless I'm running lithiums.

I really want to stick with NiMHs for routine usage (although, I'd want to be able to run with lithium for winter emergencies).

I've been very attracted to the Opalec Newbeam (especially for the same brightness with NiMH!), but I'd like something a bit brighter.
 

vcal

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Originally posted by ikendu:
Is there a Luxeon made to run with 2 or 4 NiMH AAs?

The posts I've been reading on the CMG Reactor seem to say that I won't really be happy with it unless I'm running lithiums.

I really want to stick with NiMHs for routine usage (although, I'd want to be able to run with lithium for winter emergencies).

I've been very attracted to the Opalec Newbeam (especially for the same brightness with NiMH!), but I'd like something a bit brighter.
<font size="2" face="Verdana, Arial">I'm feeling similarly...but have you thought about dat2zip step-up sandwiches?
 

Slick

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3 AA NiMh's work just GREAT to drive a Luxeon. They will not push it as hard as 3 AA alkalines, roughly about 700-950Ma for the NiMh vs. 1.3-1.8 amps for alkalines
shocked.gif
(in the same flashlight). This is what I recomend for use in my "LGI's", however you SHOULD let them sit over night after charging them. Freashly charged NiMh's are BRIMMING with power to dump and might cause a overpowering problem (although I've never experienced one).

To sum up what I've said, 2 NiMh's will NOT be enough, and 4 will be too much.
 

Jonathan

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There are two 'easy' measurements that can be used to describe batteries. Voltage and internal resistance.

Voltage is what pushes the current through the load. Internal resistance is the aspect of the battery that lowers its terminal voltage as the current increases.

Alkaline cells have a nominal fresh voltage of 1.5V, NiMH are 1.2V. But NiMH have much lower internal resistance. This means that _if_ the voltage of a set of NiMH cells is too much for a particular Luxeon, there is very little internal resistance to limit the current. Alkaline cells, on the other hand, have lots of internal resistance which helps limit current flow.

What this means is that if the NiMH voltage is a bit high (as Slick mentioned, this can happen if freshly charged), and if the forward voltage of your particular Luxeon is low, then you can see LED frying current.

If you are using a regulated system, NiMH cells will _often_ work well where Alkaline cells work. This is because the lower 1.2V rating of the NiMH cells will pretty well balance out the voltage lowering effect that the Alkaline cells see.

-Jon
 

vcal

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Ikendu-a combination that really works super efficiently and will let the Luxeon live a looong life is to use 2-AA NimH, driving the Amber emitter.
cool.gif
 

ikendu

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Originally posted by Slick:
Freshly charged NiMh's are BRIMMING with power to dump and might cause a overpowering problem (although I've never experienced one).
<font size="2" face="Verdana, Arial">Hmmm. I've been thinking of getting a PT Attitude and running it on 4 NiMH AAAs. Since the Attitude is unregulated, would I be risking frying it?
 

lemlux

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As aI've posted elsewhere, I have two of Mr. Bulk's dimmer LGI's. I think "dimmer" simply mens that they happen to have higher forward voltages, as they don't heat up much with 3@ alkalines or 3@ NiMHs. I get very good brightness and run time with unregulated NiMHs.

As Jonathan and Slick suggest, an individual Luxeon's forward voltage requirement is the luck of the draw. My two LGI's appear to be relatively dim when run on only two lithiums and a dummy.
 
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