story time guys, this one is going to be good.
So i have been gathering parts for the board for quite a while now, about two months. ebay delivery times are frustrating.
My Friday activity was esk8 stuff. First thing was to finally make a fiberglass encloser for the board. It’s drying as i write this post and it came up great:
Next thing was to have a little fun with my setup:
12S1P 18650s battery --> anti spark switch --> amp,volt meter --> VESC --> motor
The setup wasn’t connected to the board itself because of the fiberglass so i just put all the components on a small skateboard i have.
Started to play with the motor: gas, brake, gas brake. At a certain moment the motor stopped completely, one of the FETs on the VESC started smoking and the red led on the VESC turned on. I quickly turned the anti spark switch off and than figured the vesc got stuck for some reason and that if i turn it on again it’ll be OK. sort of like restarting it. WHAT A MISTAKE.
Turned it On. FET started smoking again and with no warning one of the batteries in my setup burst and started releasing gas. Moments past and another battery burst into flame.
Side note: The batteries i had were two 6S1P connected in series, both of them were made by me from 18650 LG HG2 cells. Those M***********s burn like a nuclear reactor. A complete surprise to me. Did not think they can burn like this.
I ran to take my lipo guard bags and thru the battery that kept burning into one of them. I figured that it’s going to continue burn till all the six cells are dead. I was not wrong cause the moment i thru the battery into the bag another flame burst from it. Till then i managed to run to my balcony and put the bag on the window. It kept burning and it seemed as if it’s only starting to get stronger. I knew i cannot throw it to water but i do not have a suitable fire extinguisher.
I looked down to the street and saw no one was down there so i thru the bag to the street since the chance of it burning the asphalt was lower than the chance of it burning my furniture. Then i ran downstairs to check weather it was OK and it was. The fire was out. Then i remembered there was the second battery, at this moment I already realized those batteries can burst out of nowhere when their hot - and they still were. ran upstairs and everything was alright. The scene ended.
WHAT AN ADRENALINE RUSH.
- I checked all the FETs on the VESC and all but two are down, means their drain-source resistance is zero.
- The FETs on the anti spark switch are down as well. made it just this week
- I clearly remember that first thing that happened was the motor stopping and the FET smoking.
- I did not have a fuse on the spark switch.
- The motor seems OK, all the leads are shorted and nothing is shorted to it’s housing. But i have no means to check weather it’s working.
- That’s the second VESC that i break :(. This hobby is starting to be pricey.
My personal conclusions:
- A big mistake not to put a fuse on the switch. It would have prevented the fire.
- Those lipo guard bag are life savers they did the job and did not melt.
- I need a suitable fire extinguisher.
- I’m going to pad the inside of my encloser with the material the lipo guard bag is made of.
- I cannot be 100% sure but by the sequence of events it seems that the VESC got wrong first. I’m really starting to be frustrated from the product.
Some obliviously requested photos:
Hope you can learn from my mistakes. Cheers guys.