This iteration is based on the Mk V, and incorporates the slim 100A BMS and LiitoKala “7Ah” cells which I’ve grown fond of. This and Batt Mk VI were quicker builds for ham friends, and omitted the automotive fuse on the output. The rest of this pack stuck with the tried-and-true design.
General Specs:
Created: January 11, 2020.
Cells: LiitoKala 32700 7Ah 3.2v LiFePO4.
BMS: 4S 100A 12.8V BMS Balance Proection PCB Board (a.k.a. “small thin 100A”).
Configuration: 4S1P.
New since last make: None, based on Mk V.
Current Owner: K6ARK Adam.
Cell specs:
LiitoKala 32700 cells
Nominal Capacity: 7Ah (6.5Ah in practical use)
Nominal Voltage: 3.2V per cell
Dimensions: 32mm x 70 mm
Weight: 145g per cell
Internal resistance: less than 8 mΩ
Cycle life: > 2000 cycles, DOD at 80%
Input charging voltage: 3.65v/cell
Input charging current: 3A
Continuous discharge current: 30A
Max discharge current (pulse): 6C
Discharge cut-off voltage: 2.5V
Charging temp: 0-45°C
Discharge temp: -20°C – 60°C
Storage temp: -20°C – 45°C
BMS Specs:
Continuous discharge current: 100A
Instantaneous discharge current: 150A
Charging voltage: 14.8V
Charging current 10A max
Overcharge detection voltage: 3.75±0.05V
Overcharge detection delay time: 1300ms
Overcharge release voltage: 3.6±0.05V
Balance detection voltage: 3.6±0.05V
Balance release voltage: 3.59±0.05V
Balance current: 58mA
Over discharge detection voltage: 2.1±0.08V
Over discharge detection delay time: 145s
Over discharge release voltage: 2.30±0.1V
Over current detection voltage: 200mV
Over current detection delay time: 20ms
Over current protection current: 120±10A
Over current protection release: cut load
Detection condition: Exterior load short circuit
Detection delay: 300us
Temperature protection: Can use external temperature switch
Main circuit conduction resistance: <= 20mΩ
Working temperature: -20°C to 80°C
Dimensions: 70mm x 60mm x 8.5mm
