IF25A - USB recharging OK with 18650 and 21700?

The IF25A comes with a USB-C port for in-body charging of the 21700 battery. I was wondering if I use a 18650 battery with the included 18650-21700 adapter, can I still use the flashlight to recharge?

I have a Wukkos WK30 that uses a 26650 battery, and I wonder if I can use its in-body charging port to charge 18650’s too. Are most 18650/21700/26650 batteries interchangeable in terms of charging?

Yep, they all charge to 4.2V so use whatever you want. The built in BMS (Battery Management System) will charge them all to around 4.2V (although lots of my latest lights only charge up to about 4.15V but good enough and better for battery life… by a smidgen)

IF they fit without force- you can interchange them on any of the three form-factor platforms— if they’ll fit… and charge away! :smiley:

Has anyone measured the charge current? If it is not too high of a rate it should be fine. Also it would depend on your cells specs.

Pretty sure all those (modern) cells can easily charge at the highest USB-A can deliver. Remember, the USB-C port (on MOST of these lights lately including this one) is only for convenience and durability at the light’s plug. They don’t actually charge at the USB-C spec.

OP is using the USB-C cord that came with the light’s BMS “built into” the driver and it charges to the USB-A spec. So charging takes longer than in a modern battery charger which can push these batteries full way faster than any USB-A BMS (on most USB-C ported lights) can.

That all said, I’d bet it takes all day to charge my SP33-V3 on it’s USB port :stuck_out_tongue:

I have measured 2 amps on the FT03 and the SP36. That is ok for a good single 18650 cell but maybe a little high for everyday use. The FT03 is 26650 and the SP36 is 3x 18650. The IF25A is probably less but not sure. Most likely no concern.

Does anyone know if these built in chargers output the same amps regardless of the cell being charged?

Edited to IF25A rather than SC31 pro

Using a 2.4A charger (meaning the charger isn’t limiting the current to the charge circuit), I measured the IF25A charge current at 1.4A when the battery voltage started out at 3.5V. This was on the 21700 battery it came with.

That’s a good charge rate for both 18650 or 21700. Not that slow either. Thanks river345