I suppose it is time to face reality. We have won the battle most completely. And we have lost the war most entirely. I concede defeat reluctantly, petulantly and never with good grace. But it is time to finally admit, I was wrong about the Battery Management Systems and/or Battery Monitoring System issue. And I’m just going to have to live with that.
In the win column is of course the entire top balance/bottom balance issue. In this episode, Jason Horak, the one most severely talented example we have of a man who can make an electric vehicle stop in its tracks at will, demonstrates rather empirically the efficacy of bottom balancing in allowing you to recover ALL your cells after an egregiously unfortunate event with your batteries.
Having had both the Speedster Duh (discharged to 6 volts across 57 cells) and the Toyota pickup (about the same across 48) BOTH recover ALL cells after almost identical mishaps within the past two months, the hypothesis is pretty much working theory at this point. You can protect your cells from overdischarge by bottom balancing.
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We also know from about 30 EV fires now that the best way to avoid the corollary of over discharge, overcharge, is to avoid the top balancing BMS systems entirely.
I’ve had a couple of “signposts” epiphanies over the past year I will relate briefly.
The first is Rich Rudman of Manzanita Micro. In a brutish attempt to make a joke, and sport of me and the whole “zero drift” concept, at EVCCON last year he noted that he charges every day, and every day his top balancing BMS gets REALLY hot. His analysis of this is that the cells must drift a LOT to cause all that balancing to be going on, resulting in all that heat. Proof positive that they DO in fact drift….
As I happen to know that the drift of the cells is so small you would need to address it about once every five years, he alerts us to a significant and clearly observable phenomenon nonetheless. He may not come to us from the great NASA layoff, but I have no reason to question his honesty. He either observed the heat or did not and he asserts he does observe it.
They ARE shunting current in an attempt to equalize voltage at the top of charge, and if that works, then why does it have to work again the next day? Why DOES his BMS give off heroic amounts of heat every day if in fact they are top balancing the cells.?????
His hypothesis is that I’m totally wrong on the drift concept. I have to struggle with that. But ok. Maybe. Actually no. We know too much about that to accept.
So the remaining possibility is that he isn’t actually top balancing the cells at all? Now how could that be. The circuit basically measures the voltage of the cells, while charging, and cells that reach a certain voltage, you shunt the current that WOULD go into the cell into a resistor or something so that the energy does NOT go into the cell, while maintaining energy flow into the other lower voltage cells. One by one, all cells will be brought to the SAME voltage, and the same amount of shunting and you will be top balanced.
If this is so, then on the morrow, if you discharge the pack and then recharge it, the cells should arrive at the same voltages at the same time, and very little shunting should occur at all. As they are already top balanced, they should STILL be top balanced and the process terminate very quickly. But it wasn’t terminating. It gave off a lot of heat every day.
So we have two possibilities, either they are coming UNBALANCED during the discharge and charge process, or they are NOT achieving the top balance as designed.
Now we know that we can DISCHARGE all the cells and “balance” them at 2.75 volts. If we then charge them, and DON’T top balance, when we discharge them again, if we do so carefully so that any cell reads 2.75 volts after stabilizing, that we can indeed read very close to 2.75v on ALL the other cells. This is empirical, demonstrable, and repeatable. Jason can repeat it.
So that leaves the possibility that they are not being top balanced AT ALL. What a thought.
The other epiphany was the very excellent battery test graphs that Mr. John Hardy of Surrey UK provides us. In one of these, John refers to the writhing of snakes at the top. Once cell will rise in voltage, while the one next to it actually FALLS – while charging. Then the falling cell will rise, and the rising cell will fall. If you see four or six or eight of these together in different colors, it looks like snakes battling over a cricket.
Understand that this is observed by zooming in in both time and voltage so we are displaying millivolts across seconds or minutes. Pretty big zoom factor. Zoom out and they all rise and level off. Zoom in and you seem them bouncing along at the levelled off place, actually writhing in agony.
Semiconductors can actually measure and respond somewhat more quickly than the human time frame. We can picture the process, rarely the speed. How many times a second is a BMS measuring voltage, and adjusting current levels through the shunt. We think of it as CONTINUOUS. But you can chop the time zone to the degree you want to observe – with test instruments of course.
They THINK or VISUALIZE charging to a certain level, and then shunting at a certain level when it “levels off”. That rather assumes it levels off. But if at the more microscopic level it isn’t level at all, but each cell rising and falling rapidly, what would happen to the resulting shunt current? It too would rise and fall rapidly and in tandem of course.
So why do the cells rise and fall minutely at this “level” we are holding in our Constant Voltage phase.
Let’s go back to the crowded night club analogy I used before. In theory, lithium ions are intercalated into the carbon crystalline matrix. And ideally they occupy every other space in the matrix with an empty space between each ion. In this three dimensianal world, entering ions take the first available seat. But later entering ions, having a like charge, displace them to a seat more interior in the matrix.
So for the first ions entering the matrix, it is analogous to going into the nightclub at 5:15 PM finding an empty room but an open bar. You can just walk in to the room and up to the bar and order a beer.
But as a crowd starts to gather at 8:30 PM, you have to walk around and between people to get to the bar. Some of them move to accommodate you. Your path is zig zag through the crowd to the bar.
Now by 10:30 PM when the club is in full swing, for you to enter the door at all, several people have to move to accommodate your entry, and their movement causes several other people to move as well and this travels like a wave through the crowd.
At maximum copacity, for anyone to enter the room, EVERYBODY has to move a bit to accommodate and the normal distance people are comfortable with between each other is quite diminished. In fact, we are kind of touching people all around us. And it’s hard to move through the crowd at all.
Unlike a gas, this may not be an entirely uniform process. Some parts of the room may be more densely packed than others. And if 10 people near the entrance tire of the constant breeze from the door, and move deeper into the room, there’s a sudden opening where several people can enter unimpeded. But then it is more or less “full again”. Eventually, even the deeper, less desireable locations within the bar will be filled with humanoids, a bit under the influence of ethanol and perhaps even available for other late night activities if you play your cards right.
And so this diffusion action of lithium ions intercalating into the carbon matrix, might just have a varying pressure at the “door” depending on the random position of lithium ions in an actually fractured and broken series of matrixes exhibited by each carbon granule.
If you observed this pressure or voltage at the microscopic level, it would tend to vary or bounce around this level “average” both exceeding it when it was difficult to get in and perhaps falling slightly below it when a clump of ions redistributed making room.
But there is a further interaction. We have a BMS trying to vary the pressure on the cell in reaction to what it reads there by shunting current. And this varying pressure reacts with the diffusion pressure and becomes interactive in some time zone.
I would like to propose that instead of referring to this as top balancing, we more accurately depict it as cell charge masturbation. We are jacking off our battery pack. And while it is not likely to cause pregnancy, it will create a little excitement in the form of heat.
That hypothesis eases my mind with regards to the daily heat generation of the BMS. Of course, semiconductors age and fail rather readily in the presence of heat. In failing, they don’t limit current and we overcharge the batteries. If we overcharge them sufficiently, they will of course burn your car, your garage, your house, or your warehouse to the freaking ground. Or say a Norwegian Ferry.
So how are we winning the battle and losing the war?
We currently live in an upside down Alice in Wonderland world. You can actually have a latino neighborhood watch captain who MENTORS black kids in the area, get in a fracas with a known black ne’re do well who attacks him and beats the crap out of him, characterized as a RACIST who goes out at night and hunts down negroes to murder. In our media he was actually morphed into a white guy – a cracker no less.
A Korean airlines crash where in the media we actually had a blond lady aviation expert explain the relationship between knots – nautical miles per hour and mph, statute miles per hour, exactly BACKWARDS with no comment from anyone else on the program or indeed on television AT ALL.
An intern at the NTSB responded to a San Francisco television stations request with the names of the crew of the airline. Imagine the TV stations’ embarassment when they learned that SUM TING WONG and WI TU LO were NOT the actual names of the crew members in the crash. Indeed HO LEE FUK and BANG DING OW were also madeup names.
And the dumbing down of America and twisted Up id down and down is up surreal presentation of reality gets extended to public policy.
The CALB cells we sell everyday are shipped all over the world for years now. Not ONE has every caused a fire or even heated up in transit. But because of some incidents with “lithium” cells, a term almost certain to cover a multitude of sins and cell types, we have actually crafted and deployed certain Department of Transportation “regulations” involving our batteries. We can no longer send them USPS. We can no longer send them ANYWHERE by air. As shippers of the batteries, we have to undergo DOT “training” and be “certified” to ship cells. We now pay $750 per year for a special Hazmat hotline and have purchased HAZMAT stickers with that hotline number on them. We pay a $30 per shipment surcharge on ALL cell shipments. Actually we don’t pay shit. YOU pay for all of that when purchasing the cells.
We have once again solved a problem without an actual single incidence of its occurrence. The inmates have taken over the asylum. ANd of course YOU are to pay for their totally uninformed indeed moronic attempts to do good and make you safe from everything but a clue.
Alice in Wonderland.
I have spent years of intensely focused effort on devining what these cells actually do do and don’t do in a series of given circumstances. We have actually devised a very simple, inexpsive, elegant and TOTALLY EFFECTIVE way to stop the infernal loosening of cell connections that plagued all electric vehicles. Our braided straps and Nordlock washers, devilishly simple, have just STOPPED this problem. You can tighten a connection and it is tight forever now.
We have the simplest means possible of avoiding the overcharge of battery cells and the connected fires. Just undercharge the cells deliberately. We don’t have any writhing of snakes because we never charge them that fully.
And we’ve developed bottom balancing procedures that I admit are onerous and vexing to perform – ONCE – but appear totally effective at preventing cell death and perhaps even from capacity loss due to overdischarge.
But I’ve heard the most amazing thing from three different viewers in a single month, all pretty serious OEM wannabees. All three acknowledge that as best they can tell, I”ve probably got it right. But it doesn’t matter. They have to have a BMS anyway, or at least CLAIM to have a BMS anyway, or there are liability issues they just cannot appear to have not done something about.
And no doubt they are correct in that line of thinking. In fact, if they keep burning up cars with the BMS’s, I would predict that within two years it will be ILLEGAL to operate an Electric Vehicle without a BMS – to prevent fires – which ironically are caused by the BMS.
IS this too improbable for belief? Certainly not. As I said, you are paying $30 per shipment and for a sTICKER with a HAZMAT hotline on cells that have never burned anything up anywhere!!! ITS THE LAW.
So how are we going to deal with this IN Alice’s house?
When in Rome, do as Alice does. The most ridiculous upside down thing that might spring to mind would be for Jack Rickard to develop a BMS. And so we are going to develop a Battery Management System.
Or is it Battery Monitoring System. One thing we’ve always had going for us is nobody can actually really tell you what BMS stands for with any authority. Or really what it is supposed to do. It’s like a blue elephant gun. As long as it prevents sightings of blue elephants, the details of how it works are not precisely of interest. It’s a gun, and it is VERY effective at completely eliminating BLUE elephants from the neighborhood. In fact, there’s never been a failure. Worldwide. Since the development of the blue elephant gun, there have been NO sightings of blue elephants WORLDWIDE.
So if blue elephant guns happen to burn the occasional house to the freaking ground – well – small price to pay wouldn’t you say? If only ONE CHILD IS SAVED from the horrors of the dreaded rogue blue elephant….well need I say more….
So like the kid on Christmas morning, digging through the pile of horseshit, I’m just certain there has to be a pony in here somewhere. What if, what if we built a BMS that didn’t burn ANYTHING UP AT ALL?????
In April of this year, Sendyne announced a new chip that measures shunt currents with heretofore unparalleled accuracy and manages to measure LARGE currents and SMALL currents both with very good accuracy.
The SFP 100 Current Measurement IC looks like a bit of a breakthrough to me – even though kind of pricey at $27 per chip. We are having some small success with the new 32-bit 84 MHz Arduino Due on both the GEVCU project and my efforts at controlling and configuring the TC Charger. Let’s do some design criteria.
1. Accurately measure ampere hours and kilowatt hours IN to the pack and OUT of the pack. Not JLD404 accuracy. Lab accuracy.
2. Measure pack voltage accurately.
3. Break the pack into four sections measuring the voltage of each of the four sections. We will dynamically compare the voltage of these four quadrants. They should be IDENTICAL plus or minus some small amount and that balance between them should hold for cells charging, cells at rest, and even for cells DISCHARGING at 1000 amperes. If any vary, it indicates we have a problem cell. While driving, we don’t need to know WHICH cell. Operationally it doesn’t matter. We are not going to replace the cell while operating the vehicle. If we know we HAVE a bad cell, we can determine which cell is bad with shop equipment that we don’t have to carry and won’t burn anything up with two hundred sphagetti wires.
4. Let’s measure temperature. Accurately. And let’s say in four places in our pack.
I don’t really want to defeat our NORDLOCKS. So let’s drill out some M8 stainless steel bolts and insert the temperature sensor and the voltage tap IN the bolt so we are actually measuring internal anode temperature at four places in our pack.
5. Provide relays like the JLD404 that can be used to set daughter mode, disable the controller, disable the charger, or whatever you want it to do with regards to ACTION you can take on the knowledge.
6. CAN bus reporting to make information on pack voltage and current available to other devices in the car.
7. Perhaps a bluetooth interface to show pretty dials for instrumentation on tablets, smart phones, or dash screens.
So that’s my entire wish list for a non-incendiary BMS. And using this, you could claim to anyone who cared that your lithium battery pack was fully protected by a Battery Management System of the highest order and sort.
In short, it is entirely possible to both monitor and manage a lithium battery pack with no balancing function at all. The top balance is a ridiculously simple minded adaptation of the lead acid cell thinking that you have to top balance to avoid the damages of cell drift caused by internal discharge. The lithium batteries NEVER DID HAVE AN INTERNAL SHUTTLE MECHANISM to support cell drift at all. The reason I knew there was no cell drift is we lack even a THEORY of cell drift for these cells. No one has ever described how it might work in a rocking chair cell. What I’ve known all along in a dialog with the Rich Rudmans of the world is that their base assertion doesn’t actually have even a theoretical basis in these cells. Aging differences due to temperature would be so slight that it would essentially be irrelevant to operating the pack.
Jeff Southern has offered to help me with this project and I would expect it to take some time to develop. Perhaps other viewers might join in as well. The irony of an EVTV BMS product offering is not lost on me. But there’s no particular rush. We do pretty well with the JLD404 for now. But I think something more advanced may be in order. I just have to come to grips with the oddity that we have won the battle, and indeed lost the war. If asked if we have a BMS, I can see a day where the answer MUST be oh, yes. We have an excellent BMS – safest in the world.
Jason Horak has very generously made a more graphic presentation of EVnetic’s logger.exe program available for your consideration. He calls it the Soliton EV Display and Data Logger. It might save you from his front seat full of various test equipment if you face examining the same issues. And it is likely to be otherwise and variously useful.
I find it ironic watching the Affordable Health Care Act implode on deployment after the democrats successfully shut down all Republican resistance to this heroically expensive mess that promises to end health care in America.
One of the basic premises of this act was to “end discrimination” in health insurance. Previously, if you had a pre-existing condition – meaning you were already sick, health insurers would simply blackball you. Deny you insurance. And then of course they also “discriminated against women” charging higher rates than men on the mere basis that women go to the doctor about five times more often than men.
Incredibly, now they are talking about not only ending these discriminations, but deploying NEW ONES with different rates and programs for the obese and of course for everyone’s whipping boy, the zigarrette smoker.
I have smoked non-filter cigarettes pretty much continously since 1968 and have a very unusual blood cholesteral level of about 125, no serious health problems, and visit a doctor about once every two years for a flight medical and VERY occasionally to have my ears washed out. But they insist it is “only fair” to prevent me from costing you all more money because of my health. More Alice in Wonderland.
I had the idea some years ago of giving smokers at least a quiet symbol of protest against this constant persecution and discrimination that has now become an international sport. Herewith, the Raucher Pin.
We are also going to have 4 inch patches made that are more realistic semblences of the Juden badge. And we are of course considering a line for the obese – another victim group to which I might be able to lay some legitimate claim.
I put this up a couple of days ago So far, over 90% don’t realize its a joke, and about half don’t even have any knowledge of the historical reference. But the pin is real. ORDER TODAY. Remember SUPPLIES ARE LIMITED.