Batt 9 is a build with tried-and-true components. It uses the HX-4S-F100A BMS, which is probably too permissive for the cells, but is quite reliable. The cells once again (like the Mk IV) are LiitoKala “7Ah” cells in 4S1P.
The changes to this battery are the usage of Anderson PowerPole connector for the charging port in addition to the main output. The reason these dual-port BMS’s are used is for the possibility of simultaneous charging and load. The intended recipient of this battery has a strong preference for putting PowerPole on All The Things™. This battery also incorporates sticky cardboard backing paper to seal off the back and bottom, in addition to neoprene on the bottom and corners.
This build follows the more traditional form of the earlier versions, but includes USB.
General Specs:
Created: November 21, 2020.
Cells: LiitoKala 7Ah 32700 3.2v LiFePO4
BMS: HX-4S-F100A 100A continuous (though cells max at 30A continuous); 10A max charge (should only be charged at 3A max).
Configuration: 4S1P
New since last make: Powerpole charging port, battery cardboard backing.
Current Owner: K8MRD Mike
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:
HX-4S-F100A BMS
1. Continuous discharge current: 100A
2. Instantaneous discharge current: 120A
3. Charging Voltage: Iron lithium charger 14.8V (Switching power supply: 15V-16V)
4. Charging Current: 10A(Max)
5. Overcharge detection voltage: 3.75V±0.05V
6. Over charge detection delay time: 1300 ms
7. Over charge release voltage: 3.6V±0.05V
8. Electricity equalization detection voltage: 3.6V±0.05V
9. Electricity equalization release voltage: 3.59V±0.05V
10. Electricity equalization current: 58mA
11. Over discharge detection voltage: 2.1V±0.08V
12. Over discharge detection delay time: 145s
13. Over discharge release voltage: 2.30V±0.1V
14. Over current detection voltage: 200mV
15. Over current detection delay time: 20mS
16. Over current protection current: 120A±10A
17. Over current protection release: Cut off the load
18. Detection condition: Exterior load short circuit
19. Detection delay time: 300us
20. Over current protection: Cut off the load
21. Temperature Protection: Can use an external temperature switch
22. Main circuit conduction resistance ~20mΩ
23. Working current: ~30uA
24. Working Temperature: -20°C to 80°C
25. Size: 70 x 60 x 8.5mm
