DenCo™ - Can you believe it?

The DenCo Batt Mk VII was the first to incorporate a USB module to power up to 2.4A of 5V USB power for devices. This iteration also included balance leads (much like RC batteries) so that one could use a BattGo BG-8S Battery Meter to see each cell’s voltage.

Also new in this build was a 3D printed bracket that held the voltmeter and the USB module.

This battery took 2 months to put together (mostly due to laziness and lack of a specific need). It was started in mid January 2020, and finished on February 29, 2020 (leap year).

General Specs:
Created: February 29, 2020.
Cells: Varicore 32700 6Ah 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: USB output, 3D printed voltmeter/USB bracket, based on Mk VII.
Current Owner: WE4B Jeff

Cell Specs:
VariCore 32700 3.2V LiFePO4 cell
Nominal Capacity: 1C Discharge capacity, >= 5.5Ah
AC impedance: <= 8m ohms
Dimensions: 32mm diameter, 70.5mm height
Weight 145g
End-of-charge voltage: 3.65V
End-of-charge current: 0.275A
Charging method: 1C (6A)
Max continuous charging: 6C (36A) 10-15 min
End-of-discharge voltage: 2.0V
Max continuous discharge: 33A
Max pulse discharge (5s): 55A
Cycle life: >= 3000 cycles 1C / 70% DOD
Storage performance: 60 degrees C 10-day capacity retention >= 90%
60 degrees C 10-day capacity recovery >= 92%
Charging temp: 0 – 45°C
Discharging temp: -20°C to 65°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