I contacted the seller of the controller and motor kit but undaunted he claims that all the damage was due to the battery and the fuse which he said did not work. All he deduced by looking at the photo of the burned scooter in which you can see the frame and little else. How he came to draw this conclusion remains a mystery to me.
The fuse was recommended by him from 150A and the battery (at a characteristic level) was recommended by him.
Description of the event in which the fire occurred:
"Since it was not a short circuit of the battery (besides, as soon as the smoke came out I opened the contactor) the only option is that during the slowdown from 60km / h to 0 the controller has suffered damage. I repeat once again what I said, I was traveling at about 60 / 65km / h after slowing down after overtaking. When I tried to accelerate again to go back to 80km / h I noticed that the scooter was no longer responding to the accelerator commands. This problem had already occurred previously presented, but at low speeds, between 20 (about 1050rpm) and 30km / h (about 1600rpm). I solved earlier by turning the key and opening the contactor circuit (excluding the battery) and closing the circuit and scooter started. That day, however, it was not like that, by turning the key and opening the contactor circuit, the controller did not reset from the error. Before reopening the contact of the known white smoke contactor and trying to stop at the roadside and instantaneously I open the contactor circuit, but the combustion of the controller does not stop. I tried to put it out with my jacket but it was too strong to put out and I knew that if the fire heated the battery too much I would be at risk, so I walked away looking for help from passers-by. Meanwhile the fire had already wrapped the fairings in plastic and the saddle of the scooter and I could not do anything more to tame it and I waited in the distance for it to go out. Help came too late. "
Seller:
"Suppose the controller has an internal short circuit, then in this time, the Feus circuit breaker should trip and the BMS should cut the power as well. But the result is that the battery etc. is still working as you stated in the last one. email, so it means BMS and fuse and circuit breaker didn't trip at that time. So it means there is no short circuit. So from this perspective, it means our controller is not a problem.
Thank God, get off the e-scooter on time and you are safe. But in reality, the battery broke on its own, it will first produce a little smoke, then slowly draw fire. It doesn't stop right away, because the battery is combined one by one. So the first is broken, then the second. "
Certainly a short circuit produces high current, but a short circuit of the lithium cells causes instant damage to them. The cells react by heating up to about 65-70 ° C, sometimes with deformation of the cells. The battery is instantly unusable as it no longer produces current. This hypothesis is to be excluded since the fuse has not tripped, and neither has the circuit breaker. Furthermore, the BMS would also cut power if a short circuit occurred. The battery was still functional and healthy, as the lights, voltmeter and everything connected was still functional at the start of the fire.
The only event that produces a battery explosion (not smoke, but instantaneous explosion) is overheating, that is the strong overheating of the battery cells, for example if exposed to fire, which happened, in fact in the video we note how some cells explode (like fireworks) as a result of overheating caused by the flames. The only event that causes smoke from lithium cells is punching them (it is not enough to hit them with a hammer, you have to damage them internally) laterally, sending anode and cathode into contact within the single cell itself (an event that produces little smoke and a instantaneous explosion of the cell). If a short had occurred (and the fuse, circuit breaker or BMS had not blown) the battery would have exploded while I was still on the scooter, and thankfully it did not. From this it is clear that it was the fire that damaged the battery (and the whole scooter with the rest of the components). Fire caused by the explosion of the controller components, mainly the electrolytic capacitors, which are known to release considerable smoke on rupture followed by the development of flames. The electrolytic capacitor contains a wet separator inside and will dry out of the unit by becoming too hot, causing an internal short to develop. Certainly the current developed by the decelerating motor has damaged the controller by overloading the capacitors, causing them to break with consequent emission of white smoke and flames fed by the surrounding components and by the plastic that covers everything.
I hope to get a refund, and in any case I would have already lost the money for customs taxes and total destruction of the scooter. I could make use of the Italian legislation for the protection of defective and unsafe products which very clearly states that "any damage, even to third parties, caused by a defective and therefore unsafe product caused to things and / or people is the responsibility of the seller, unless is a pre-sale contract in which such compensation is waived ".
