CREE Q5, consequence of no power driver

Hey I have a cree Q5 flashlight, I did not like that the flashlight came with 3 different modes: Hi/low/blinking. I took it apart and bypassed the driver completely so I don't have to click the button so many times to turn it off. So the Q5 emitter is receiving 4.5v directly. (what is the M amps for that? please answer also) A guy at a television repair shop shot me down telling me that the led would eventually burn out. Is this true?

Isn't this a re-post?

In your other thread you mentioned 3 AA's.

If they are alkalines you will probably not have a problem.

If they are NiMH you *might* overdrive the LED, depending on the Vf of the LED.

Yes it is a repost. I don't understand why I didn't get hardly any replies. How come I don't get any replies? Do I need to be a member for a long time for people to reply? I would understand that...

Anyway...thanks for your answers greg...

Your question requires a bit of specialized knowledge as to the exact emitter specs, and there's a good chance most people here didn't know what to say so they didn't reply. I can't even give you a solid answer other than "probably", but I think you should go for it if you don't mind breaking the light. Especially if it's much brighter. And once you do kill the emitter, you now have the perfect opportunity to put in a new LED and driver of your choosing.

If you are worried about burning out the emitter why don't you just buy a single mode driver and put it in very cheap and simple solution.:twothumbs

NathanH1991 said:

Yes it is a repost. I don't understand why I didn't get hardly any replies. How come I don't get any replies? Do I need to be a member for a long time for people to reply? I would understand that...

Anyway...thanks for your answers greg...

Click to expand...

It is practically impossible for us to know for sure if you will have a problem. The issue is that we don't know what the front voltage of your LED is.

Out of the last batch of Q5's I purchased from ETG, they ranged from 3.2 volts to 3.8 volts at 1 amp of current.

Worst case scenario, let's hypothetically say you have a low Vf emitter, and it draws 3.2 volts at 1 amp. You would be fine with alkalines. With NiMH you could overdrive the emitter, depending on the resistance in the light (switch, etc.).


If you have a good DMM, you might try checking current at the tailcap. It would give you an idea, but keep in mind the DMM will lower the current of the light when in place.How much? Depends on the DMM.