As a part of our JET-CART PROJECT, which kicked off in June, 2021, we encountered a need for a high-capacity battery (400Wh). As there was no battery of needed parameters on a market, it’s been decided to design, build a couple which we can use for initial testing and also produce on our own.
The project involved following steps:
- Battery design
- Battery rack design and printing
- Cell testing and spot welding
- BMS (Battery Management System) selection and integration
- Battery pack testing
- Power distribution
Whole process got documented in following posts:
2X TURNIGY HIGH CAPACITY 20000MAH 4S 12C LIPO PACK W/XT90
MAKE YOUR OWN BATTERY PACK – PART I
18650 VS. 21700
6S POWER!
STORY OF THE “EBIKE BATTERY PACK 24V 30AH ELECTRIC MOTOR BIKE BICYCLE LITHIUM ION WITH CHARGER”
MAKE YOUR OWN BATTERY PACK – PART II
MAKE YOUR OWN BATTERY PACK – SPOT WELDING FUN (PART III)
MAKE YOUR OWN BATTERY PACK – WE HAVE A BATTERY PACK! (PART IV)
BMS RESISTANCE
BATTERY PACK EVALUATION
The tesla fuse idea is worth considering – rather than spot-welding a big fat strip of nickel on each cell, they instead weld a single thin strand of wire from the cell to a bus-bar. The strand is designed to melt like a fuse if more than a safe amount of current should ever try to flow through it. With one on both ends, that’s literally like having 10,000 individual fuses on a 5000 cell battery.