Healthy batteries,that have solid connections, and are checked regularly for cell internal resistance and pack total resistance are not likely to explode.
If you check your packs, and know your packs, you’ll know when your pack is unhealthy and likely to do such.
It doesn’t “just happen”
I’ve been using lithium for a long time, I know my packs, I take care of my packs, I’ve never had an 18650 vent, and the only time lipo explode is when the cells are damaged and unsafe to be discharged, and I puncture them with a spike on a stick from a safe distance.
Again batteries don’t just explode for no reason, there are causes
-punctures
-over charging
-over discharging
-shorts
-crushed
Etc
They’re fine at 12S under 60amps and under 40mph loads for people under 200 pounds. Running them on lipos with crazy vesc settings under crazy high loads will do one of a few things that i have seen:
through some mystery of science cause the fets to lock into the on position. I suspect the load just welds it into place when it gets to hot. Who knows. I see this 99% of the time when they fail.
explode the fet with visible fragmentation. I’ve seen this twice.
heat up the solder to the point of reflow and literally move the fet over untill it shorts and either blows up or cooks something. I’ve seen this only once, and the BMS caught the short before anything else was damaged.
I’m working on one now with 2oz copper and three of these fets instead of two, and also some bolt down fuses. As soon as the parts arrive i’ll assemble a few and we’ll see how they do. I’ll be open to selling a few at cost for testing before i retail them.
One thing to note about the “over discharging” one
This only applies to two things
-damaged cells
-discharging under heavy load(more then the pack is rated for, or an old cell with high IR that can no longer produce it’s rated current and now generates heat at high current draws)
While over discharging at a low wattage load such as a 12v auto/car bulb under 50W on a NOT DAMAGED cell that is dying due to high internal resistance, is a safe way to completely discharge a cell for recycling/disposal
If it’s 18650 - discharge and recycle as individual cells
If it’s lipo pack - discharge to 0v, cut the positive and negative terminals and twist together to make inert and throw in trash
If it’s a lipo cell by itself - discharge to 0v and then puncture the cell through to ensure the layers are shorted and inert then toss in trash
If it’s a lipo cell or pack, that cannot be safely discharged,go-to a fire safe area OUTSIDE(concrete/asphalt), put a nail on a fiberglass rake handle and puncture it, let it burn off and cool then toss in trash
If you read anything about saltwater and lithium packs, it’s wrong, all it does is corrode the leads off leaving a charged pack, the only way to use salt water is on packs that have preexisting punctures. As manually puncturing a pack will…well you know
i’ll know more when the PCBs arrive and the rest of the components come in from Mouser. Also i’m busy finishing up the first Carvon EVO prototype off my bench so… i’m not saying it will be a while… but it might be a minute. That board needs to be finished this week, and its thursday already.
And i’ve got a steady stream of business coming in. And i’m probably going to start writing for a magazine soon, and i’ve got my own youtube show i’ve been toying with in my head that needs to happen, and i’m writing a book. And i’ve got to test these BMSs and remotes, and i want to build a board on 76mm kegel cored wheels i found… and i just bought a 12th scale RC buggy to try and rig up a low angle follow cam…
@pshaw Get @SORRENTINO to print you one out of ABS, we’ll acetone smooth it and paint it matte, use a black male xt90, then rit dye the yellow antispark side black…
I suggest against using knock off xt-90s.
I measured the resistance in a real one vs several off brand and the off brands always had 50% to up to 200% higher resistance
@pshaw I used a 3d printed xt90 socket holder for making a clean key, here it is on the side of the battery box…found the model on the interwebs and James Curtis printed it for me. they are handy to have, print a few…Yes…I know, it needs some Abec11 97mm reflex…
As far as the control mode you described when you just kick push and the vesc keeps up the speed its already a thing. Ackmaniac’s modded firmware has it. Its called PID controlled mode and you can still use the remote for breaks.
Do you make these (3D print) or do you purchase these? Also, what is good XT90 (name brand) vs off brand? Which brand is the good one? I would like a couple of the panel mounts for my next build. I can purchase if you wish.
