2x26650 -VS 6x18650

In one of my higher power setups I use the following cell configurations:



Tailcap current draw with the 2xIMR-26650 cells is 3.75A (31.5W)
Tailcap current draw with the 6x18650 cells is 3.95A (33.18W)

I was positive the 2x26650 setup would blow the 18650 cells out of the water, but thats not the case at all.:thinking:

1- Is my observation typical for multi-18650 setups like this?
2- Are my 26650 cells no good?
3- How much current is being drawn from each individual 18650 cell?
4- Is the exposed -Batt metal (red arrow) at risk of shorting?

thanks!!
:thinking:

kramer5150 said:

In one of my higher power setups I use the following cell configurations:

Tailcap current draw with the 2xIMR-26650 cells is 3.75A (31.5W)
Tailcap current draw with the 6x18650 cells is 3.95A (33.18W)

I was positive the 2x26650 setup would blow the 18650 cells out of the water, but thats not the case at all.:thinking:

1- Is my observation typical for multi-18650 setups like this?
2- Are my 26650 cells no good?
3- How much current is being drawn from each individual 18650 cell?
4- Is the exposed -Batt metal (red arrow) at risk of shorting?

thanks!!
:thinking:

Click to expand...

Bit like comparing a 4cyl engine to a V8 ... More cells = less strain on each cell .. So I would dare to say the 26650's are doing rather well .

Since you have 3 parallel chains of pairs of batteries in the 18650 config, each 18650 (assuming they are relatively equal batteries) will see 1/3 of the total current. Or 1.32 Amps each.

Martin D. White

on the shorting thing, WHEN/IF you connect the top batteries CAN, to the bottom batteries CAN it can cause a short. just put in a ring spacer of cardboard.
The can, on most of this stuff is one of the poles of the battery, and it runs the whole length, just rip the insulation off and you will see quick enough.
as long as it doesnt crush or lean into the edge, and the insulation holds that is there, it will be fine. extra insulation would be to put in the ring that keeps the cans from ever making contact.

also depends on what you use to make the contacts between them, if it is interconnecting the series units into a parellel single X3 Also. Just dont want the interconnect to rub through the insulation and contact the CAN or outer ring at the top either.

| . |
| . |
| . | <----La CAN, or negative terminal metal thing
| . |
|__|

This doesn't really help you with the batteries you have, but I've had a couple of people tell me that the AW 26500's will deliver more current than the Batteryspace 26650's:thinking:. Maybe less internal resistance:shrug:. You might already be aware of this, but I thought I'd share it in case you not, but like I said, it really doesn't have anything to do with your original question.

kramer5150 said:

In one of my higher power setups I use the following cell configurations:

Tailcap current draw with the 2xIMR-26650 cells is 3.75A (31.5W)
Tailcap current draw with the 6x18650 cells is 3.95A (33.18W)

I was positive the 2x26650 setup would blow the 18650 cells out of the water, but thats not the case at all.:thinking:

1- Is my observation typical for multi-18650 setups like this?
2- Are my 26650 cells no good?
3- How much current is being drawn from each individual 18650 cell?
4- Is the exposed -Batt metal (red arrow) at risk of shorting?

thanks!!
:thinking:

Click to expand...

Did you measure voltage drop across the cells while under load? Was it a regulated circuit? I would like to see the voltage drop and compare it to the current draw. I know in a regulated flashlight my IMR cells have a lower current draw than Lico cells due to maintaining higher voltage under load but in a direct drive flashlight they will produce a higher current and voltage making the light brighter.

You have to take into consideration that when you parallel 3 18650's together, they are in effect, a single cell with a capacity which is the sum of the 3 individual cells added together. I would think in most cases, this would amount to their being considerably higher in capacity, and thus likely able to hold voltage under load better than a single 26650. I would think that 3 18650's in parallel would more closely approximate a 32650 in performance, although the IR may come into play in this case, and give the 32650 an advantage.

Dave

Results are not surprising. I would suspect that 3 18650s would outperform a single 26650 in voltage maintenance/current performance test. The 3 18650s represent more volume and should represent better performance all other things being equal.

I've also found, that having more cells, even if they are totaling up to be smaller in consumed volume than a single larger cell, can result in better performance under loads. 4xAA alkaline cells will out-perform a single D cell for higher current applications, but it's about 10% less volume.

Hey kramer5150

I am wondering what flashlight you are going to put 6x18650s into. Is this a modified light, or one you are making from scratch.

I ask because I also have plans for a 6x18650 flashlight, but I am having a hard time finding one to mod (and I don't have the machining skills or tools to make one myself).

Cheers!
Battery Guy