headlight with cree mc e an hipflex on 3,7V

hi,
is ist possible do drive a single MC E in parallel on 3,7V liion cells.
i want to build a headlight an so i want to use a accupack with 2 18650 liion cells (parrallel).
in fact when they are full loaded, there are about 4,2V and in the hipflex manual there is a information that there are 0,5V drop current, so the mc e will drive on 3,6V - 3,7V.
but i don't know how the mc e work on this current (3,6V - 3,7V). does anyone know if that current was high enough to let the led shine bright?

thx from germany

:candle:

I don't think this is going to work well the the voltage from the cells will drop a lot under load. You could put the cells in series and then the hipflex should be good. Alternativly you could get a series wired MCE and the use a maxflex again with two cells in series.

Ifor

yes, using a maxflex and a serial wired star is both cheaper and more efficient. But you need to put the sells in series as the input current will be on the limit fopr the maxflex if used in parallel. (close to 4A)
If you already have a parallel pack you may want to look at a AMC7135 based driver. Those are very efficient when used with input voltage close to led Vf.
They are also very cheap.

Edit: you can also wire the MC-E 2s2p and connect to a maxflex driver, then you will have a maximum of about 600ma/die instead of 700, but you will have no problem driving it from 2 Li-ions in parallel.

I have an MC-E wired in series that I am direct driving with a single IMR 18650. It gets really hot, but other than that, there have been no problems. The current draw is 2.8 to 3A.

You could look for one of the drivers for the SSC P7 and use it with the MC-E wired in parallel. KD has a few and they are about $15 for the multi-level ones. That would keep the heat down when you didn't really need that much light.

Kevin