Quote:
Originally Posted by ions82
I've wondered the same thing. I think it is highly unlikely the Seg batteries would catch fire. They are, literally, "bulletproof." I remember a Valence Saphion promo video where they shot the cells with a gun. No fire. Regular lithiums burst into flames. So, I'd feel OK in using the voltage supply trick on a pack that still has Saphion cells, but I wouldn't be as confident If trying it with a rebuilt pack. Some accounts I read in which individuals revived their own packs said it only took a matter of minutes of supplying voltage to a dead pack (showing less than 10 volts) to bring it back up to a "chargeable" state.
Also, as Jason from MTO mentioned, even successfully reviving a pack doesn't mean that it doesn't have bad or degraded cells. It may have a couple bad ones but is still perfectly useable. For how long becomes the question. It's amazing that a lot of these Segway packs that are ten years old are still kicking. It's a testament to how well the cells and BMS are engineered. But as Don mentioned, the only way to store the Seg unplugged is to remove the batteries. Otherwise, they risk that early/untimely death.
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I remember that video. What everyone shoudl consider is that Saphion is just a brand of lithium iron phosphate battery. It is no different than Coke being a soda. In fact, any UN38.3 tested/approved lithium iron phosphate battery will do exactly what you saw in the video. Our rebuilds react the same if punctured. In the end Saphion cells aren't any safer than the ones we use in rebuilds but rather it is a name that was marketed quite well. Lithium iron phosphate is certainly a "safer" chemistry of lithium than lithium cobalt or lithium manganese etc..
I also wanted to clarify my statement since your reply made me question whether I was clear enough in what I wrote. "Even successfully reviving a pack doesn't mean that it doesn't have bad or degraded cells". That part I agree with. I do not agree that a pack with a few bad cells is perfectly usable or safe. In many cases the BMS would restrict use based upon dead/inferior cells. Be well!