Output measurments of different cells

Hi, did anyone made a compassion of different chemistry types 18650s?

High drain PD/PF vs B/A/IMR and other type of cells…

Lumens per cell or amps per cell on same driver/flashlight assuming all fresh when compared? thanks.

Do you know this? http://lygte-info.dk/

I know, what i wanted to know is how voltage sag affect the lumens output :slight_smile:

Well, I think that the best way to find out is to look at the discharge curve of different cells at the current that your flashlight drains. The higher the voltage the better.
Then about the driver: If it is tested by HKJ on that site I gave you then you’ll find the graphs of current vs input voltage. In that case you have everything you need I think.
If nobody tested it then there is no way to be sure.

Your flashlight drivers are direct drive, linear or boost?

Boost i think on both TK61/TK75…

I already ordered the PF2900 mah (Orbotronic PD in the graphs) but still was curios to see :slight_smile:

Boost drivers should keep the LED current constant for most of the discharge curve. At some really low voltage it’ll start dropping however…
I don’t know your driver, but in general boost drivers can ouput the same amount of current/lumens for a wide range of input voltages.

Yes, i’m aware. But at 4.5A + it kinda gets complicated….(modded lights)

I don’t have any results to give you as I don’t have that driver/light.
However on the same driver, the better the cell holds its voltage at 4.5A the better it’ll be.
But again, if your boost driver is smart enough to output a constant current, it won’t change much. The only difference could be that it’ll keep that level of current for longer.
That’s all I can say, maybe somebody will be able to give you results.
If you have other specific questions about the electronics and stuff I might help though…

Yes that’s why i’m a bit worried. With my Panas 3400 mah protected, i get around 35/40 mins on turbo, and after that, the light goes to high after 2 mins from turbo…it drops the output.

You have 4*18650 in parallel in your light right?
4.5A total means about 1.2A per cell which is not much. I’m surprised it won’t hold that for longer.

The PD/PF would probably be your best all around choice in those kinds of lights, easily giving 4-5A and sustaining that for the longest amount of time. The new Efest 35A gives much more current and at 2500mAh is not so terribly far behind the Panasonic cells in capacity.

The Samsung 25R is also a mid level choice, giving more current but less runtime than the Panny’s but less current than the Efest.

If you’ve already got the Panasonic on the way, you made a good choice.

Edit: Panny PF’s give more current for longer than the 3400mAh versions from them.

But wait… Are you sure that the driver is of the boost type?
I doubt that as a bosst driver steps up the voltage and the LED needs about 3.3V which is lower than the batteries.

It really depends on the light.

On TK61, even modded. You might as well use stock NCR18650B. Absolutely no reason to use any high drain cells.

See the stock section of this TK61 teardown/mod thread. Its perfectly regulated from a buck driver. And even with cells almost fully drained. The light will not pull more than 1,1A from each cell (when stock).

Unless the drain on each cell is more than 3A, its no use to go for PF/PD over the typical "B". HKJ`s webpage shows discharge graphs nicely. Those graphs combined with the knowledge of how much a light is able to pull gives you the answer to which cells are best suited. With a DMM you can always measure how many amps it pulls.

I often see see recommendations of using "high drain" cells, even in lights where its not needed. Lights that are well regulated and does not put a lot of load in each cell.

If the light is not properly regulated, output will often start to sag at some point. In my X6M review you can compare output between two different Keeppower cells. First its some sag due to heat. Then you will see better how voltage sag between the different cells works on output.

This light has a 2S2P battery config? Interesting.

I saw this post for the TK75 mod… (batteries drain) keep in mind i’m new to this stuff…