Test/review of Sony US26650FT 3000mAh (Green)

HKJ · 2018-08-28T15:46:04.000Z

Sony US26650FT 3000mAh (Green)

Official specifications:

Nominal capacity: 3000mAh
Nominal voltage: 3.3V
Chemistry: LiFePO4

This is a LiFePO4 cell, i.e. the voltage is lower and the discharge looks very different from normal LiIon. The two cells are very well matched.

Most of the discharge the output voltage is very flat, voltage mostly depends on discharge current, not on charge state.

Conclusion

This chemistry has lower capacity, lower voltage, but much better lifetime. The batteries looks to be high quality.

Notes and links

Vapcell told me that I was missing some cells in my comparator and they would be happy to supply them.

How is the test done and how to read the charts
How is a protected LiIon battery constructed
More about button top and flat top batteries
Compare to 18650 and other batteries
Compare to 26650 and other batteries

djozz · 2018-08-28T17:40:02.000Z

Pretty cool cells, it would be so nice if LiFePo cells came in a bit higher capacity then they would be great for modern low voltage leds and lineair drivers. Thanks for the test.

antonkochubey · 2018-08-30T06:13:47.000Z

Woah, a new decent LiFePO4 cell! Previously, all we had was remaining stock of A123 cells, and complete junk from SoShine & similars. Nice.

Are you going to test the 18650 version as well (US18650FT)?

HKJ · 2018-08-30T06:56:54.000Z

Shadowww:

Are you going to test the 18650 version as well (US18650FT)?

I do not have the cell, but if I find it I will test it.

adam7027 · 2018-08-30T09:46:03.000Z

Looks like a very interesting cell. I also would be happy to see something very similar in 18650 format. They would be very good to drive red, far red and infrared LEDs with linear driver.

They could be useful for some very low Vf Nichias as well.

EasyB · 2018-08-30T13:15:58.000Z

The flat voltage curve means it has sort of built-in regulation, but it doesn’t seem as sweet when you see it has less than half the energy of the shockli 5500mAh 26650.

BlueSwordM · 2018-08-30T13:37:11.000Z

No regulation.

Justvery low internal resistance and discharge curve of LifePO4 cells.

djozz · 2018-08-30T13:38:00.000Z

EasyB:

The flat voltage curve means it has sort of built-in regulation, but it doesn’t seem as sweet when you see it has less than half the energy of the shockli 5500mAh 26650.

What is sweet to me is that LiFePo cells have no safety issues, which makes them suitable for purposes that li-ions are not suitable for.
I can see a USB-rechargable flashlight that has the light output of a 4xAA flashlight but is more compact. Someone care to talk Sofirn into a D4S with 4 LuxeonV’s, USB-charging and this cell, putting out 3000 lumen over the entire discharge of the battery?

Or mod it! Just put XP-L2’s in a D4S and this cell, and watch how high the sustainable output is!!! (assuming that the MCU runs at the lower voltage, and ai, there will be problems with LVP kicking in way too soon)

EasyB · 2018-08-30T14:33:22.000Z

BlueSwordM:

No regulation.

Justvery low internal resistance and discharge curve of LifePO4 cells.

Obviously there is no voltage regulation circuit in the cell, but it’s sort of regulated in that if you connected an LED direct drive the current would be essentially constant over most of the discharge of the cell.

led4power · 2018-08-30T17:09:31.000Z

djozz:

What is sweet to me is that LiFePo cells have no safety issues, which makes them suitable for purposes that li-ions are not suitable for.

They are safer because of higher tolerance to thermal runaway, but they still use the same toxic and flammable electrolyte.

Barkuti · 2018-08-30T17:32:03.000Z

Shadowww:

Woah, a new decent LiFePO4 cell! Previously, all we had was remaining stock of A123 cells, and complete junk from SoShine & similars. Nice.

Are you going to test the 18650 version as well (US18650FT)?

There are other players in the LiFePO₄ league: Bench Test Results: EnerCig EC-IFR20C 46A 2300mAh LiFePO4 26650...great cell, close to A123 @ E-Cigarette Forum

I believe such cell is manufactured by Heter Battery.

Cheers ^:)

shlfn1 · 2019-12-05T10:58:31.000Z

Hi HKJ, I have recently come across a heap of these cells in a 8S 14P configuration with a Sony (assume balance) pcb. Scored 12 in total with 8 reading 26.XX volts & 4 packs with nil voltage on any cells,I have experience with Li ion 18650’s but wonder if its worth trying to recover these lifepo4 0 volt cells, any advise would be appreciated, thanks.