Thermal runaway of batteries adiabatically (ARC-type mode), provides safe temperature limits and limits on discharge/overcharge rates using BTC (Battery Test Calorimeter). Different designs to allow both small scale testing and large battery packs (largest dimension over 55cm).
Main Thermal Runaway Tests
Safe maximum working temperature
The maximum temperature of the environment which results in a battery thermal explosion that can be predicted
by placing the sample in the BTC and performing well established adiabatic tests.
This involves stepwise heating, followed by a wait-and-search period can be used with cells and large battery
packs alike to determine the maximum safe operating temperature.
Over-charging and discharging limits leading to battery explosion.
It is also important to determine how a thermal runaway can be triggered when a battery is discharged at too fast a rate or if it is overcharged (voltage too high).
The results of a 3-cell Li-ion polymer battery connected to a cycler and discharged at 15A, while placed inside the BTC are shown.
Battery short simulation
Battery shorts are a huge concern as they can often lead to thermal explosions at any time. The consequences of this can be simulated
by artificially creating shorts between the terminals, while the battery sample is inside the BTC. A range of resistances can be tested to
allow for ‘soft’ and ‘hard’ shorts.
A short video illustrating and explaining the visualisation process inside HEL’s adiabatic calorimeter – the BTC (Battery Testing Calorimeter), during charging / discharging tests. Please note that there is no sound recorded with the video.
A video of a nail penetration test performed on a Li-ion battery.