Organised by INDY partner CAFA Tech, a ballistic battery test in Estonia evaluated the reaction profiles of different battery chemistries when shot with a 7.62 calibre bullet. The results provided valuable insights into the safety characteristics of these batteries, which are critical considerations for military applications.
Notable attendees included John Zevenberger from TNO, Stamatis Petrogiannis from Intracom Defence, and several military experts from the Estonian Defence Forces.
Five different promising battery chemistries were tested. All battery packs had an approximate energy capacity of 600 Wh and were fully charged to their limit and loaded with 150 W of power during testing. Each battery was subjected to two shots fired by a marksman in a prone position, ensuring consistent targeting across the packs.
The following battery chemistries were tested:
- Lithium-ion (NMC)—The battery exhibited one of the most violent reactions. Individual cells exploded and shredded the pack, causing the fire to last intensely for approximately five minutes.
- Lithium iron phosphate (LFP) – Displayed a relatively modest reaction with no explosions or dark smoke. The battery burned calmly for about 20 minutes, reaching a peak temperature of 200 °C.
- Lithium polymer (LCO) – Reacted the most violently and rapidly. It produced significant dark smoke and large flames. The intense reaction lasted about a minute, with temperatures exceeding the 400 °C limit of the thermal camera.
- Lithium titanate oxide (LTO) – Had the mildest reaction, producing only light smoke and no flames. The battery temperature remained below 100 °C throughout the test. Compared to other batteries, LTO produced a very distinct smell when damaged.
- Sodium-ion—This battery showed a medium-level reaction, with a few cells catching fire and propagating flames. The reaction produced no dark smoke. The fire was extinguished after 3 minutes, with the temperature peaking at 140 °C. Notably, this was the only battery that remained in working condition after being shot and could supply 150 W to the load.
The tests provided critical data for assessing the viability of various battery chemistries in military applications, highlighting their performance under extreme conditions and their safety implications.
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