This battery turned out to be the basis for several other batteries. It incorporates a new 100A “slim BMS” that I found from Aliexpress. I also integrated neoprene padding to help cushion the overall pack, although this padding is a false sense of security as the battery cell holders are very fragile and will crack with any impact even with padding. This Mark 5 version has fused main output, extensive amounts of kapton tape to protect the cell heads, and uses LiitoKala cells.
General Specs:
Created: September 8, 2019.
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
25A automotive fuse on main output
New since last make: New BMS, neoprene padding added.
Current Owner: K6HZR Jose
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
