
Poor bugger.
https://www.youtube.com/watch?v=O-PaSSTA2YE
Kurt
[ Edit Coulomb: it turns out that bottom balancing had nothing to do with this, see 3 posts down. ]
Yes, I don't like Jack or his ideas much but..."There but for the grace of God go I.".offgridQLD wrote:Probably something we all should think about when playing around with batterys. Minimize the risk for the .000001% chance something unexpected happens.
Kurt
offgridQLD wrote: He has a video up now about what happen with pics of whats remaining.
Starts about 40min into his video.
Kurt
His two recent blogs give no further information about the fire. They consist almost entirely of right-wing homophobic political and religious rants having no relevance whatsoever to batteries or EVs.Jack Rickard wrote:POP. BANG.
What was that? Sounded like somebody banging on one of the closed garage doors. BANG POP POP. What the hell?
I went into the next room to see who was banging on the door, but as I reached to open the door, the POP POP BANG sounded again but BEHIND me. I walked over to the Better Place battery pack from the Renault Influenza that we use on the OEM components test bench. BANG POP POP. These are actually pretty loud. What the……?????
This pack was right out of the cargo container and we never even attempted a bottom balance. We were only going to use it for testing chargers and DC-DC converters and the UQM test bench. But as the result of one of our assclowns playing around with the bench while I wasn’t in the shop, it had drained down very slowly overnight to a very low level.
It seemed to charge back up ok. But never quite got to full charge. So I had hooked it up earlier in the afternoon to bring it up some more.
I quickly shut off the charger and cut off the contactors. But it continued to BANG and POP irregularly. I can’t leave to go to bridge with it like this I’m thinking. As there had been several of these “no show” moments in the past few weeks where I threw my wife under the bus with regards to one plan or another, this was not really good. I can’t believe I’m doing this again.
Suddenly the pack begins to issue the familiar white smoke – just a bit at first, then more. The pack weighs 450 lbs, and the fork lift is at the other end of the building. I went over to the wall water spigot, glad I had a couple hundred feet of hose there to water our grass. No hose. Assclown somewhere had made command level decision to move it down to the basement in the other building apparently. There was a hose, but it was four feet long.
By this time the white smoke was coming out pretty good. I don’t know why, but I was curious what the temps were. So I grabbed an infrared gun and shot all the cells. Most were warmish in the 35-40C range but there were two sitting at 95C. Not good.
Suddenly the pack spewed a spear of sparks and flame about six feet straight out the front – right where I had been a moment before. And then it exploded into a massive fireball shooting flames up to the ceiling with such velocity that they splashed laterally from there.
Yes. But we don't want to "let the smoke out" either, since it means the cell is destroyed. And that "smoke" is possibly blinding and lung-corroding, and definitely highly flammable and with a very low flashpoint, and so it is quite likely to turn to flame. And yes, a poorly designed BMS could well be the ignition source. But a well designed BMS will prevent it from happening in the first place.T1 Terry wrote: Try to keep in mind the Jack formed his philosophy of no BMS and bottom balancing using LiFeP04 cells, they don't burst into flame, just "let the smoke out"
That would be quite an admission. So I went looking. It wasn't in the video, but buried in the comments after it. Thanks for correcting me on that, Terry.I think in the first video after the fire he says that these chemistry batteries probably can't be used without a BMS.
Ya think?Jack Rickard wrote:I guess I think a BMS is probably in order with these.
Which seems to imply, "If it was possible to bottom balance them, no one would need a BMS, even with this chemistry", which is a complete non-sequitur.I’ve had little luck bottom balancing them.
Yes a Nissan Leaf pack would go in exactly the same way if used without a BMS and abused in the same way. Why do you say "not much more than" when that's all you need in a BMS, to prevent catastrophe. There is no active temperature control of the battery in a Leaf.T1 Terry wrote:Does this mean the Leaf battery pack could go the same way? Let's face it, the vehicle BMS is not much more than staying well away from the top and bottom areas as far as battery capacity and temp monitoring. Tesla have active cell temp control but does the Nissan Leaf?
So where did he go wrong? He thinks the copper shunts (dendrites) form during the over-discharge. They do not. They form when you recharge after an over-discharge. So presumably he thought that since the cells hadn't got hot immediately after the deep discharge, there must be no copper shunts, so it must be perfectly safe to recharge them. Wrong!Jack Rickard wrote:What happens when we over discharge our cells? Well, we are moving lithium ions from their cozy location in the graphite on the anode, through the electrolyte and into the cathode. If we continue past a certain level, a couple of things happen AGAIN. First, we again go into oxidation and produce CO2 and our batteries swell. Second, we start to emerge copper from the copper foil the anode rests on through the carbon in a streamer we will refer to as a shunt. It penetrates the separator and connects to the next “cell” that is, between two foils inside the cell. ANd it shorts them out. The more of them that are shorted, the less cell you have active. And they cause heat. The most common cause of death is over discharge. You cannot make the shunts go away. A little swelling is telling. But the shunts are death.
Thanks for clarifying. We have misunderstood each other.T1 Terry wrote: The not much more than refers to not monitoring individual cell voltages to determine end of capacity or end of charge, nor do they monitor or control cell temp as you have pointed out.