FT has Feilong 32650

[LEDAdd1ct]

@Paranid

They also have FeiLong 32650 5000mAh LiFePO4 Link

I hope they add some 18650 and 26650 LifePO4s as well.

I would love to know the real capacity of 32650 LiFePO4 at a low current draw, say 50 to 100mA.

I was thinking about getting two and running an XM-L2 at low currents for an emergency light.

Though we’ve established the LiCo 3.7v cells true capacity,
there is just about zero information on the LiFePO4 cells under the Feilong label…

[leaftye]

Back in stock.

[sacra]

I know it’s been explained time and again how the energy density of 26650s and 32650s are lower because all the R&D is focused on 18650s but it’s still troubling. Here’s a 32650 with 3x the volume of an 18650 and and only 2x the average capacity (and much less than 2x that of a top-of-the-line 18650 cell). Assuming wall thickness and electrolyte composition is the same across cell sizes, that basically leaves the electrodes and the amount of electrolyte as the variables.

So what’s at play here? Does the electrode in a 32650 occupy a greater percentage of the cell’s volume compared to an 18650? A naive envelope calculation assuming electrode surface area scales with cell volume suggests that’s true but the corresponding decrease in electrolyte volume (as a percentage of call volume) doesn’t come close to the decrease in energy density that we see in reality. Perhaps the electrode size is dictated by some maximum allowed distance between the electrode surface and the most distant electrolyte ion?

Anyway, it’s a shame 26650s/32650s have lower energy density than 18650s. I recognize that one of the attractions of these larger cells is their higher discharge rates but I like the simplicity (and relative safety) of single-cell flashlight designs and the thought of a single-cell light that can run for 4-6 hours on high makes me smile.

[B42]

@jayrob

@leaftye

I’m hoping these new cells are still good. They’d make a base for an awesome battery pack. I’ve fallen in love with the 26650 platform, and now I want to switch to 32650’s. Luckily for my bank account, the flashlights aren’t available yet.

FS: 1000 Lumen XM-L U3 Mag mod with voltage monitor!

FS: Vintage Ray-O-Vac XM-L U3 Mod! (1000-Lumen)

“FS: 1000 Lumen Vintage Eveready XM-L U3 Mod

Shameless plug…

Ha, those are kind of neat. You should give one to Dale’s grandpa so he can compete with Dale’s lights.

[B42]

@sacra

I know it’s been explained time and again how the energy density of 26650s and 32650s are lower because all the R&D is focused on 18650s but it’s still troubling. Here’s a 32650 with 3x the volume of an 18650 and and only 2x the average capacity (and much less than 2x that of a top-of-the-line 18650 cell). Assuming wall thickness and electrolyte composition is the same across cell sizes, that basically leaves the electrodes and the amount of electrolyte as the variables.

So what’s at play here? Does the electrode in a 32650 occupy a greater percentage of the cell’s volume compared to an 18650? A naive envelope calculation assuming electrode surface area scales with cell volume suggests that’s true but the corresponding decrease in electrolyte volume (as a percentage of call volume) doesn’t come close to the decrease in energy density that we see in reality. Perhaps the electrode size is dictated by some maximum allowed distance between the electrode surface and the most distant electrolyte ion?

Anyway, it’s a shame 26650s/32650s have lower energy density than 18650s. I recognize that one of the attractions of these larger cells is their higher discharge rates but I like the simplicity (and relative safety) of single-cell flashlight designs and the thought of a single-cell light that can run for 4-6 hours on high makes me smile.

One of the other attractions is maintaining higher voltages for longer periods of time as well. Maybe this is a less mAh storing chemical energy mix per volume that maintains higher voltage for longer as well. I agree it seems they should be significantly higher mAh though…