# EVTV fire



## dougingraham (Jul 26, 2011)

It sounded like the only EV damaged in the making of this film was the Mini-Cooper.

From what I understand it was one of the Better Place packs had been run down flat earlier in the week and it was on charge when a couple of cells popped off and took the rest of the pack with them when they ignited. This would have been front and center on the shop web cam. If anyone had been watching they would have had a spectacular view.


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## RIPPERTON (Jan 26, 2010)

Cells popping is usually overvolting.
Bad BMS.
Some cells were zero and some still 2.8v when charging started


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## Hollie Maea (Dec 9, 2009)

RIPPERTON said:


> Bad BMS.


Well, no BMS. Jack doesn't use BMS, and is evangelical in his views that no one should ever use it.


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## Moltenmetal (Mar 20, 2014)

This is one of several very good reasons a BMS is worth buying.


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## RIPPERTON (Jan 26, 2010)

So did he even run through the pack and manually check all the individual cell voltages ?


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## palmer_md (Jul 22, 2011)

http://evtv.me/2015/11/a-dark-and-sunny-sunday/

In his own words....


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## RIPPERTON (Jan 26, 2010)

The penny has dropped...

_



Jack Rickard replied:
I guess I think a BMS is probably in order with these

Click to expand...

_You learn so much when shit blows up


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## Karter2 (Nov 17, 2011)

But those were/are complete packs with BMS, cooling, breakers, etc all built in.
Or had JR done some "doctoring" to it.
Even so it's more than a little concerning when that sort of event happens to someone with the experience of JR.
Lucky it wasn't close to the stock of other Betterspace packs !


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## frodus (Apr 12, 2008)

RIPPERTON said:


> Jack Rickard said:
> 
> 
> > I guess I think a BMS is probably in order with these


I'm at a loss for words


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## RIPPERTON (Jan 26, 2010)

Karter2 said:


> But those were/are complete packs with BMS, cooling, breakers, etc all built in.


They may have had BMS fitted but what charger was he using.
You are only going to prevent a fire if the BMS is integrated into the charger to switch it off.


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## Hollie Maea (Dec 9, 2009)

RIPPERTON said:


> They may have had BMS fitted but what charger was he using.
> You are only going to prevent a fire if the BMS is integrated into the charger to switch it off.


Any BMS that may have come with the pack was disconnected, as per usual.

As The Bard once wrote, "The fault, dear Brutus, is not in our stars* but in ourselves".

*Or "Assclown interns" as the case may be...


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## JRP3 (Mar 7, 2008)

This is really a shame. I've suggested to others that you probably can't treat these like LiFePO4 with bottom balancing. Sorry to see it confirmed like this.


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## dcb (Dec 5, 2009)

shit, those are renault batteries, i.e. leaf batteries, my favorite bargain...
limn204

no initial balance either.


He has another renault battery too, so not sure,
Here he is saying after opening it "If I remember that code, we have 30 seconds to comply before it blows"

https://youtu.be/YWPQTjpKovQ?t=7420


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## kennybobby (Aug 10, 2012)

i guess davide would be having the last laugh now...


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## Moltenmetal (Mar 20, 2014)

Could it be that Jack us changing his religion on this??,

A basic BMS interlocked to stop charging is pretty much critical safety gear for any lithium pack. You can eliminate the shunt charging/ balancing function, but recharging without BMS comes with risk even if you lowball the charger total shutoff voltage by a lot. Manageable risk? With a lot more care than can be expected of the average driver, then sure- but everyone gets lazy after a while. I know I do not have the patience to run around checking end of charge voltages cell by cell often enough to reduce that risk to a level I would find acceptable. BMS purely as a HVC alarm trip during charge is comparatively cheap insurance against a potentially very costly failure.


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## Caps18 (Jun 8, 2008)

Not that this is a good thing, but at least we will get some good information and recommendations on how to keep this from happening to anybody else.


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## frodus (Apr 12, 2008)

Moltenmetal said:


> Could it be that Jack us changing his religion on this??,
> 
> A basic BMS interlocked to stop charging is pretty much critical safety gear for any lithium pack. You can eliminate the shunt charging/ balancing function, but recharging without BMS comes with risk even if you lowball the charger total shutoff voltage by a lot. Manageable risk? With a lot more care than can be expected of the average driver, then sure- but everyone gets lazy after a while. I know I do not have the patience to run around checking end of charge voltages cell by cell often enough to reduce that risk to a level I would find acceptable. BMS purely as a HVC alarm trip during charge is comparatively cheap insurance against a potentially very costly failure.


Exactly. 

I've stayed away from the BMS arguments except for one piece of advice:
While people poo-poo BMS with balancing function, I'm adamant about having some sort of device that monitors cells and can shut off the load or the source in the event of an over current/voltage/temperature or under voltage situation.

No one has time to go through each cell and ensure they're balanced each time they charge. Its a pain and impossible while driving. For the longest time while Jack preached about no BMS, he WAS the BMS, monitoring cells and balancing as needed, all by hand. 

For me, I think a product that monitors cells and protects them is a requirement. Sure it costs a bit more, but it saves my investment.


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## Karter2 (Nov 17, 2011)

Jack explains...
..about 22 mins in....
https://m.youtube.com/watch?feature=youtu.be&t=1384&v=Lb75ktwoMIw


> ...A BMS is fitted,.....but not in use ..???


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## Caps18 (Jun 8, 2008)

RIPPERTON said:


> They may have had BMS fitted but what charger was he using.
> You are only going to prevent a fire if the BMS is integrated into the charger to switch it off.


The BMS that comes with these batteries is a closed box, and it won't work with the way we are using the batteries.

It looks like I will need to research BMS's now. What ones are reliable, easy to use, and can prevent any of the 56 LiMnO2 batteries I have from doing this?


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## dcb (Dec 5, 2009)

It was more an issue with pack authority than any individual cell I think is the point, a plain pack voltage monitor with disconnect authority should have caught this. A simple half pack monitor can detect most imbalance conditions. And a bottom balance would have provided a failsafe, so that all the cells run out of energy at the same time, instead of cells 1-94 turning on the weakest ones 95 and 96. Top balance contributed to this most likely, damage from the initial discharge.

Be safe and careful out there.


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## Karter2 (Nov 17, 2011)

dcb said:


> . Top balance contributed to this most likely, damage from the initial discharge......


...over discharge seems to me the major factor,...
..compounded by un monitored charging.
No amount of balance, top or bottom played a part at all
A BMS might have prevented one or both issues,...
..but the bottom line seems to be good old Human Error.


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## dcb (Dec 5, 2009)

Karter2 said:


> No amount of balance, top or bottom played a part at all


I'm inclined to agree, just pointing out one point in the causality chain here, perhaps more appropriate to testing/experimental setup purposes than production (well tested system production that is, not rush to market component "production"). Production is obviously going to want the cells at their maximum energy level. 

DIY is fairly "experimental", and trying to recover cells is gonna happen (and bottom balance minimizes the effects of inadvertent discharge by minimizing cell reversals, which also happens).


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## onegreenev (May 18, 2012)

He had the pack connected to an unmonitored load. Yes it was a small load but that is enough. He made the mistake he said not to do. I remember having 4 HiPower cells connected as my 12 volt power source for my discharge setup and when I was done the only thing connected was my JLD meter. Thats all. All the cells were balanced at the bottom. I figured that the load was not much and the cells were pretty much full. Enough to at least have it sit in that condition for quite some time. Nope. Did not happen. 4 Days later I came home to see four badly swollen cells. Dead. Since they were not clamped or anything like that they just got swollen. Had they been in a huge pack then that would be a problem. Under load, even a small one, you do not want to have it unmonitored and unable to fully self disconnect from every load at a specified voltage. That is a must. Im glad he finally took the blame himself. But I pretty much don't bother with the old guy anymore. I have not watched a full episode for nearly a year now. Just too boring and not enough building. Just hawking his wares and his arrogance. No thanks.


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## dcb (Dec 5, 2009)

well, like the scotsman, there is no "true" bottom balance, most folks don't have the nerve to take them all the way to zero before charging a string. I would like to understand the difference between 0 volts and cell reversal though (how many volts do lithium cells start life with?), but it is best avoided alltogether, but still will happen sometimes.

But that is part of the issue w/monitoring and cell level bms loads, is that they add their own small load, which seems to necessitate their existance. Complete disconnect when not running (and monitoring) or charging(and monitoring) is a viable option. It was monitoring circuits that killed both your packs, they just couldn't do anything about it.

edit, I think I will be adding a small 12v battery for vehicle monitoring purposes, it is making a lot more sense now (what? your 96 node fancy schmancy bms had a glitch? who would have dreamed of it?!?) and ensure the pack is completely out of the loop when not in use.


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## Moltenmetal (Mar 20, 2014)

Overcharging is what caused the fire.

Over-discharge resulted in the cell imbalance that made over-charging inevitable, since no BMS was being used.

Cell level BMS provides warning of both conditions. But since low voltage doesn't trigger automatic re-charge, the user is still in the loop to prevent damage from over-discharge. The small load on the cells due to the BMS circuitry can indeed cause damage if ignored for long periods, for instance during unattended storage.

Since if you care about the cycle life of your Li pack, you should avoid discharges below 70-80% DOD anyway, the primary risk the BMS is reducing is over-charge. It's worth it on that basis alone in my opinion.


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## dcb (Dec 5, 2009)

dcb said:


> I would like to understand the difference between 0 volts and cell reversal though


followup: most sources say bad things happen below about 2.45v to a cell, so 0v is kinda moot except as an experiment (to validate the 2.45 assumption).

MM, I would say anything that monitors the whole pack voltage would be terribly useful, followed by something that compares pack halves for gross imbalance, all without causing constant drain on the main pack, or its own imbalance. Would you categorize that approach as BMS? 

cell level monitoring is a level of complication and expense and variables that cause a continuous drain, unless you make them even more complicated. Granted you can get them into the uAmp range, but that is assuming every cell monitor is having a good day, every day. So I certainly don't expect everyone to be on-board with that level of monitoring and complications. The more complicated, the less reliable.

I *think* that is what people are assuming when the term "BMS" is brought up, and I think it is overkill in a lot of situations and makes new issues that are rarely considered.


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## Moltenmetal (Mar 20, 2014)

I don't agree, but of course that doesn't matter. We just have different points of view. 

Whole pack voltage isn't of much use at either the top or the bottom in my opinion- it can easily miss a cell which is high. Individual cells can be easily over-charged if there's even a small amount of imbalance, and continual perfect top balance sufficient to prevent such an occurrence is not realistic. Anyone who has bottom balanced their pack and just shuts their charger off at a particular voltage is playing roulette with the lifetime of individual cells in my opinion. You can play it and win for a long time, but eventually it could get you. If you're happy to be the BMS, checking cell voltages at the end of charge one by one by yourself frequently enough to be confident, then by all means- to each their own. I'm not, and I'm confident that most people aren't really either. They'll get lazy eventually, and the BMS is cheap insurance against it.

I have reliable Ah monitoring (by far the most useful), cell level BMS (equally useful as it is how EVERY charge terminates), total pack voltage monitoring/automatic charger shutoff (never used) AND half-pack voltage balance indication on both my front and rear packs (Lee Hart bridges- somewhat useful and they cost $1 to build, so very cheap insurance) in my vehicle. Yes, that's belt and suspenders for sure, but those packs were EXPENSIVE and they need to last a long, long time to make the project worthwhile.

Again, the concern over BMS alarm trip boards draining individual cells is not much of a meaningful concern unless you're going to be storing the vehicle unattended for long periods. And if you are, you can and should recharge the pack to 50% DOD first. Most BMS will run off a 50% DOD cell of realistically useful capacity for vehicle applications for a long, long time.


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## onegreenev (May 18, 2012)

He did say he did not bottom balance the cells. He assumed they were all good. Bad move, and from the one that has said all along to balance them all. So no, you can't use 0 volts for a bottom balance. No battery can use 0 volts for a bottom balance. You take the cell to the steep knee of the discharge curve for your particular battery. So for the LiFePO4 you go to about 2.6 and even as low as 2.4 volts. Not below. As you should have a system in place that will take that pack and shut it down completely if you reach a specified static voltage. I still follow jacks routine and if he had done what he has been touting all these years he would not have had an issue. His issue with BMS systems at the time were those that used active setups that actually shunted power to cells to match them all up when you charged them. Also finding the right BMS can still be a daunting task. How do you know what is the best. Everyone says theirs is best or acceptable. I agree you need a way to shut down a pack completely if a specified voltage is met. Using the Lee Hart battery bridge is a no brainer. It should be mandatory for all packs. It can be done. But good careful bottom balancing is going to help. 

Don't let your pack sit with a load and don't assume the load won't be a problem or that you have x about of days before it becomes a problem. I assumed with my 4 cells and this is what happened. I assume even with well balanced cells you may have an issue below the balance point you had set. My cells were balanced yet a simple little JLD meter drained them and caused this in 4 days. I was going to do more discharging and assumed it would have been able to handle that for a good month or more. I did not check exactly what kind of a drain the JLD meter was producing. Im assuming now, quite a bit more than you think.

I will still have my bottom balanced cells and a well made bat bridge will be installed.


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## dcb (Dec 5, 2009)

I really do appreciate all the testing they do at EVTV, and I know jack has learned (and shared) a lot of information about batteries and etc. This is solidly in the "stuff happens" category when you are experimenting, IMHO. Human error, yes, but I've no expectation of them being super-human.


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## Caps18 (Jun 8, 2008)

From what Jack has done in the past, these cells are difficult to bottom balance because they tend to bounce back. I checked the voltages on the packs I just finished this week, and voltages range from 7.76V (3.88V x 2) to 7.4V. But I have done nothing with the batteries and the 7.4V (3.7V x 2) ones were bought from a different vendor.

I will be bottom balancing these, but I'm not sure if there is a difference between getting them all to 6V (3V x 2) and 5.8V (2.9 V x 2)? 

Do you have any links to more information on the Lee Hart battery bridge? I will be able to totally disconnect everything from my batteries, since I might need to have it sit for months at a time. I can say that they hold a charge pretty well for 18 months.


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## onegreenev (May 18, 2012)

http://www.evdl.org/lib/index.html

Scroll down and you will find Lee Hart's stuff. 

I had no problem bottom balancing my Leaf cells. I'll let you know later my ticket on that. 

Pete


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## alvin (Jul 26, 2008)

Here is another link.http://www.sunrise-ev.com/LeesEVs.htm


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