I have a small cube-like 3Ah LiFePO4 battery from a commercial manufacturer popular with hams these days. I used it mostly with the KX3 on trips.
I saw that the K2 26650’s could be arranged in a 2×2 fashion to create the exact same form factor. Couple that with a newly discovered tiny protection board, and I conceived of a way to make a similar battery (which is good since the original commercial battery is no longer produced).
Created: March 1, 2020.
Cells: K2 26650 2.85Ah 3.2v LiFePO4 (capable of 150A pulse max).
BMS: HX-4S-3828 LiFePO4 BMS PCB Board for 26650 or 18650 LiFePO4.
Total Rated Capacity: 2.85Ah.
Current Owner: NJ7V Charlie.
Watt Hours: 9.4
Nominal Voltage: 3.2
Fully Charged Voltage: 3.65 (recommended), 4.1 (maximum)
Fully Discharged Voltage: 2.5 (recommended), 2.0 (maximum)
Continuous Discharge (A): 42
Pulse 30 Seconds Discharge (A): 50
Short Pulse Discharge (A): 150
Charge Current (A): 5
This board does NOT BALANCE.
Module size: 38 x 28 x 3.8mm / 1.49 x 1.10 x 0.15 inch
Upper limit working current: 8A
Upper limit instantaneous current: 20A
Over charge voltage range: 3.65±0.05V
Over discharge voltage range: 2.35V±0.05V
Static current: <30uA
Charge voltage: 14.4V-15 V
Short circuit protection: yes. Delay self recovery
Tips: After the wiring is successful, the board needs to be charged and activated before it has output.