tomjasz
1 GW
Jil said:
Damage that pierces a cell or shorts cells can cause a fire.
How do you store your batteries safely indoors?
- Thread starter Enkidu
- Start date
Damage that pierces a cell or shorts cells can cause a fire.
Jil said:
There have been fires with packs just sitting there unused and unconnected. The only one I recall any specifics about was John in CR some years back with a hardcase RC LiPo pack just sitting on a table or desk.
But any battery that has a charge, that has something happen to a cell causing internal damage that can lead to an internal short (at any point in it's lifetime, from factory to battery builder to seller to end-user), can fail catastrophically, self-discharging thru that short, and also discharging any cells in parallel with it.
Whether that leads to a battery fire or not depends on how fast it does this, and how hot it or other cells get, and how hot the interconnects get, and the materials around it.
It's not a very common scenario...but there is always a risk.
The cheaper the pack (and thus the less quality control there probably is of the cells themselves and of the pack construction), the higher the risk. Really cheap packs that use salvaged cells are even higher risk as you cannot know anything about the history of the cells at all before they were salvaged, and any of them could have experienced detrimental or even damaging conditions at any point in their former usage. (and sellers that use recycled cells to save money probably do a lot of other things to save even more money....).
Note that physical damage is probably the greatest risk, but other things that could cause internal cell failures include overcharging and overdischarging, especially if the cell is actually reversed in voltage by the discharge (meaning, it had so little capacity vs the other cells in series with it that when the system stopped pulling current, it had used more capacity than the cell had to give, actually reversing the cells voltage).
Cells can also be defective from the manufacturer. They would probably be rejected at QC if there is a detectable difference in the behavior of the cell, and if it's sufficient they would scrap the cell to have it destroyed...but it seems to be that some (possibly a lot or even all) of those "destroyed" cells don't actually get destroyed, but instead get resold by the scrappers that were supposed to destroy them, and used in battery packs....which means that whatever defect is in them is now latent within that pack, "waiting" to fail in whatever way it is going to.
tomjasz
1 GW
Rare as users of LiPo these days
Jil
1 kW
Interesting videos here :
https://www.youtube.com/watch?v=CnNId0mDnBo
(the failure of Lipo safety bag with the 16000 mAh battery is impressive ! See at 1:50)
https://www.youtube.com/watch?v=WR-Rw0PLgpA
(this one shows among others the failure of a Bat Safe container used above its rated capacity, see at 3:35)
https://www.youtube.com/watch?v=CnNId0mDnBo
(the failure of Lipo safety bag with the 16000 mAh battery is impressive ! See at 1:50)
https://www.youtube.com/watch?v=WR-Rw0PLgpA
(this one shows among others the failure of a Bat Safe container used above its rated capacity, see at 3:35)
tomjasz
1 GW
Jil said:
Bat safe insufficient size and can’t withstand a li ion eBike pack fire. 50-100 cells is beyond the rating for a LiPo battery.