Non IMR 18650 on Mac

[BenChiew]

Does anyone know if it is safe to run a NON IMR 18650 on one of Mac's Tri 18650 lights?
Can it handle a 2.8amps power draw?

 

[Colonel Sanders]

A quality cell will. LiCo cells are generally rated at 2c which is to say a rate twice their capacity. Personally I think 1-1.5c is better for frequent use. So, a 3400mah cell x 1.5c is 5.1a. Plenty of current to support a Tri. :thumbsup:

 

[BenChiew]

So a 2.8amps draw on a protected AW 18650 of 3100mA is below 1c, that should be comfortable.
In terms of runtime, what would be the difference between a IMR18650 2000mA and a protected 18650 3100mA?

 

[The_Driver]

Because of it's low voltage under high loads a 3100mAh (Panasonic) battery will typically not last longer than a 2600mAh (Sanyo) battery. Those are usually cheaper.

 

[BenChiew]

Are there more than 1 type of 18650 protected in 2600mA battery? Looks like i should go get some.

 

[Colonel Sanders]

Because of it's low voltage under high loads a 3100mAh (Panasonic) battery will typically not last longer than a 2600mAh (Sanyo) battery. Those are usually cheaper.

I'll bet you dollars to doughnuts that a Panny 3400 (and maybe a Panny 3100) will far outlast a Sanyo 2600 under a 2.8a load. I've done the testing on the 3400s and it takes the 2.8a load just fine.

But yes, of course the 2600s are generally cheaper.

 

[BenChiew]

Thanks guys. But what is the consensus here? I know nuts about batteries.

 

[badtziscool]

Thanks guys. But what is the consensus here? I know nuts about batteries.

There's a thread floating around here that talks about voltage of a cell for a given current draw, but I can't seem to find it.

In a nutshell, the 3100/3400 mAh cells have a slightly different design that gives it more capacity. The drawback is that when the cell is under high current draw, the voltage of the cell ends up being lower than on a 2600 mAh cell given the same current draw. Because of this, the driver must draw even more current from the battery to maintain the current draw at the led. It's this lower voltage/higher current demand at high current draw (i.e. lower efficiency) that makes these 3100/3400 cells not last as long as the 2600mah cells under high demand.

At what point this becomes true, I'm not sure, but I don't think 2.8A is it. You should get more runtime with the 3400mAh cell with this light.

 

[BenChiew]

Thank you for those explanation.