Regulation board @Kai

[RV7]

Just noticed that Kai is now offering a 2xAMC7135 driver board, which provides 700ma to the LED most of the time. To my knowledge, it's one of the most efficient circuit for single 3.7v battery configurations. The only drawback is that output drops gradually near the end. But this can also be a good thing - you'd know when to recharge the battery so you can use unprotected batteries safely.

Icing on the top - great price!! Only $10 for 5 boards. I can hardly believe it. I placed an ordered without any hesitation.

Edit: Forgot the link. Here it is:
http://www.kaidomain.com/WEBUI/ProductDetail.aspx?TranID=1746

 

[Norm]

Link please.
Norm

 

[mmmflashlights]

Another thread here:

http://www.candlepowerforums.com/vb/showthread.php?t=162646

 

[RV7]

Another thread here:

http://www.candlepowerforums.com/vb/showthread.php?t=162646

Ops. My bad. Should've done a search first.

 

[RV7]

Another thread here:

http://www.candlepowerforums.com/vb/showthread.php?t=162646

I can't agree with what wakibaki said in that thread. Not at all.

AMC7135 works like an intelligent variable resistor. When Vin - Vf >= 0.12V, it changes its resistance to maintain a constant current. When Vin drops below Vf, which probably happens when a Li Ion is half discharged, it's like a direct dirve, with only 0.12v voltage drop across it.

With some simple math, you can tell its efficiency is over 90% most of the time.

 

[moon lander]

could you theoretically hook up 2 or 3 of these to 1 18650 to power 3 leds from 1 battery?

 

[RV7]

could you theoretically hook up 2 or 3 of these to 1 18650 to power 3 leds from 1 battery?

I'd think it's okay, though it may be harsh on the battery due to the current draw.

Each LED should get its own independent driver so that they get the same current, that is to say, until the battery drops to Vf. After that, due to variances in V-A characteristics, some LEDs will be slightly brighter than others.