A reminder of lipo do's and don'ts - Fire aftermath pics

[etriker]

wrong wrong and wrong.

this is a case of an ignorant dumbass user.. buzzers going off.. WARNING WARNING.. yet keeps on charging and riding.. without reaching out to the seller for feedback = fail.

Right ? And doing it with rc lipo of all things ! The only li ion cells I have ever seen shorted were rc lipo.

They look nice with their shinny stickers on the outside but inside they are very hit or miss in quality = fail !

The dumbass thing was to put them on an ebike before tearing off the wrapper and seeing if the cells are all connected ok and remove the large solder globs ?

 

[Ypedal]

The few lipo packs i've built for customers i've made webpages for their reference:

http://ypedal.com/zippy/zippy.htm

and :

http://ypedal.com/Cyclone/cyclone4.htm
plus
http://ypedal.com/Cyclone/cyclone5.htm

Both of these guys managed KFF's, but are very intelligent people, both live close to me so each winter i demand the packs come back to me for inspection, and i have them my phone number with instructions to call me at any sign of something wrong, or un-usual, no matter what time of day.. if in doubt.. CALL.... but for god sakes.. do nto use the pack until i either ok it or inspect it personally....

mainstream ?.... pff.. hell no.

 

[etriker]

I don't have any ebike customers. Not in the biz. I do ride every day and built packs for friends.

If I was going to charge someone to build a battery pack I would never use rc lipo. Never.

 

[migueralliart]

In all honestly if you are selling "turn key" solutions to customers I wouldn't put lipos in em unless you educate well the customer. There is soooo much to go wrong with Lipos as with any other chemistry but the results are catastrophic with lipo. I have tried a couple of chemistries and built some packs from 26650 and 18650 cells (both lico and lifepo4). Even knowing what I know now when I ventured into buying my first 2 6S bricks for my entertaiment bike I read ypedals page and pretty much every single LIPO failure thread on this forum. I know there are some golden rules (which I always follow) but people shouldn't leave charging unattended AT ALL. To me it got to a point where I wouldn't charge anymore without an RC charger and balancing at the same time. This is the reason i ALWAYS charge with the balance plugs connected to my icharger 3010. I also never get a pack from hobbyking into my bike without making sure it doesn't have a bad cell or something. Also what goes in the bike can be easily retrieved in order to store in a safe area for charging. I use a small FULL METAL box (kinda like the ones they put behind the pick up trucks) and I charge my lipos INSIDE the box which happens to be vented of course. Even knowing that the box WILL contain a fire I don't leave it unattended.


BTW thanks for sharing this!

 

[mr.electric]

So the customer buys the wrong charger and plugs it into the cable going to the motor controller since the plug didn't fit the charging port.

In many cases the BMS would NOT protect against this situation. The BMS is protecting against charging through the charger port, which was not used in this case. Even if the BMS had an FET to disconnect the motor on low voltage, this path from the controller back into the batteries would be passing through the FET's inherent body diodes, and so would not be blocked even if the BMS opened the FET (which would not be part of its normal operating design).

Essentially you have a customer rewiring the setup and using the wrong charger. Pretty hard to protect against that.

The bms boards I have seen for ebike packs have a shared charge and discharge path into the bms. I am not sure how the circuit works but it only has two wires coming out that serve to both charge and discharge the pack. It seems pretty fool proof. You get
-lvc
-hvc
-current limit
-balancing
The circuit I have used most was sold by Ebikes sf before they got the new all cell brand stuff. Both the lipo and Lifepo4 packs Ebikes sf sold were wired this way. I will add a pic of the lipo board if anyone wants to see it.
I tripped the 50 amp current limit on the lipo board a few times with too much motor current. The battery shuts off until you plug and un plug it. I have never tried simply shorting one of these packs to see if the current limit function would act before something on the board melts but I feel it would have protected against the wrong charger plugged into the wrong plug scenario. Unless someone tied in before the bms which would involve dissecting the pack and soldering on a new wire. Of course if you sold enough packs chances are someone would do that as well.

 

[Ykick]

Selling ANY pack you should probably consult a lawyer. At minimum, product warning labels and perhaps a signed release or acknowledgement by the purchaser that they're aware, and have been informed, of the potential danger(s) resulting from misuse, modification, physical damage, wrong charger, etc?

 

[Alan B]

Most of the BMS designs I've seen have a separate charge management input current path and connector. Putting FET switches for current in both directions toward the motor doubles the loss during operation. Some designs don't have FETs at all in the controller power path instead controlling the throttle or shutting the controller logic power down. Bottom line is it depends on the design, and if the user is hacking the system all bets are off.

 

[Ypedal]

hell.. severely overcharge SLA in a confined space and produce enough hydrogen gas..... spark that sucker..

it's not only Lipo's that demand respect.

 

[999zip999]

But pushing a newb who just wants a plug and play battery and can't take care of a puppie or gold fish. Is just going give electric bikes a hard time. Like on a train or bus. News flash we now have a lipo bike fire on the amtrack ? Lipo has it place. It might be more of a hobby battery.

 

[Jason27]

You can't sue someone who has no money. No lawyer will take the case.

 

[Hyena]

Don't waste your money on rc lipo for your ebike

Rc lipo for ebike = fail !

Stong opinions for someone with such a low post count.
High C rate lipo for ebike use is brilliant, I wouldn't use anything else and I know many here are in the same boat. But granted, there are limitations to any battery (or any other device for that matter) and if you blatently do the wrong thing things will go sideways.
As stated there's not really a good lipo BMS solution available at the moment and I'd be worried about using one in place of manual cell checking. If they it did fail it introduces other problems and potentially could still let cells overcharge or discharge. But yes, most BMS's I've seen have a charge and a discharge lead. It sounds like this guy would have still managed to overcharge the battery anyway even with a proper BMS in place.
As Alan B said, he rewired the electrics and then used the wrong charger. How do you control against things like that ?? You can't


As for building stuff for other people, the talk of sueing is certainly off putting for those of us who build the odd ebike kit and batteries for others to try and help promote the ebike movement Fortunately the vast majority of people I've encountered are usually enthusiasts one way or the other so you'd hope they'd have the sense to do the right thing. I encourage all noobs to go with lifepo4 for the plug and play convenience and thoughtless ongoing use. The size and weight of such a pack is an instant deterrant though and usually after test riding my lipo powered bike most will much prefer lipo. I really do build these as safe and foolproof as possible but as above, you can't control for someone doing the above.

 

[HumboldtRc]

The result of what happens when you put a bolt where a fuse should have been....

6s 20ah Zippy pack

 

[Hyena]

Whoa, is that a Fisker Karma ?

 

[etriker]

Don't waste your money on rc lipo for your ebike

Rc lipo for ebike = fail !

Stong opinions for someone with such a low post count.
High C rate lipo for ebike use is brilliant, I wouldn't use anything else and I know many here are in the same boat. But granted, there are limitations to any battery (or any other device for that matter) and if you blatently do the wrong thing things will go sideways.
As stated there's not really a good lipo BMS solution available at the moment and I'd be worried about using one in place of manual cell checking. If they it did fail it introduces other problems and potentially could still let cells overcharge or discharge. But yes, most BMS's I've seen have a charge and a discharge lead. It sounds like this guy would have still managed to overcharge the battery anyway even with a proper BMS in place.
As Alan B said, he rewired the electrics and then used the wrong charger. How do you control against things like that ?? You can't


As for building stuff for other people, the talk of sueing is certainly off putting for those of us who build the odd ebike kit and batteries for others to try and help promote the ebike movement Fortunately the vast majority of people I've encountered are usually enthusiasts one way or the other so you'd hope they'd have the sense to do the right thing. I encourage all noobs to go with lifepo4 for the plug and play convenience and thoughtless ongoing use. The size and weight of such a pack is an instant deterrant though and usually after test riding my lipo powered bike most will much prefer lipo. I really do build these as safe and foolproof as possible but as above, you can't control for someone doing the above.

The hit or miss quality of RC lipo is my main problem with them. For RC use way out in the field or ebike racing it's ok I guess but to pack several of them next to each other and run them on the street is risky.

I am not willing to risk getting another EV battery fire on the news because I wanted to save a few bucks on batteries.

 

[Rodney64]

as I'm new to lipo I decided to charge my 24s pack with a elcon bulk charger. This was the advice my Battery builder gave me. More expensive but safer.

When the pack gets to 100.8 volts it stops automatically.

 

[999zip999]

My konion's LiMn cells have had vent fires (3), cute. In 500 used cells. Just enough to melt plastic and have heard of lifepo4 fires. There is alot of energy in these batteries. All of them. Start a fire with a 9v. and steel wool. Love to have the power of lipo.

 

[Hyena]

to pack several of them next to each other and run them on the street is risky.

No it's not, they're not going to just suddenly explode
Again common sense - put them in something to protect them. And even people who foolishly just duct tape them to their frames rarely run into trouble even when crashing (there's been several stories of people dropping or grinding their packs into the road with no ill effects, though obviously this is asking for trouble)
Watch some of liveforphysics destruction videos and see what's REALLY required to make modern day lipo blow up.

It sounds like you've already made up your mind though...

Rodney, as a new user and in general I'd advise you to drop that voltage a little. Bulk charging to 4.2v/cell average means you're almost certainly going to overcharge some cells, even assuming you balance afterwards.

 

[etriker]

to pack several of them next to each other and run them on the street is risky.

No it's not, they're not going to just suddenly explode
Again common sense - put them in something to protect them. And even people who foolishly just duct tape them to their frames rarely run into trouble even when crashing (there's been several stories of people dropping or grinding their packs into the road with no ill effects, though obviously this is asking for trouble)
Watch some of liveforphysics destruction videos and see what's REALLY required to make modern day lipo blow up.

It sounds like you've already made up your mind though...

Rodney, as a new user and in general I'd advise you to drop that voltage a little. Bulk charging to 4.2v/cell average means you're almost certainly going to overcharge some cells, even assuming you balance afterwards.

I took some failed packs apart. I really think they were made not to last a long time. Born to give a big bang and fail early.

And the cells can short. This stuff is for out in the field RC use.

 

[Alan B]

Selling ANY pack you should probably consult a lawyer. At minimum, product warning labels and perhaps a signed release or acknowledgement by the purchaser that they're aware, and have been informed, of the potential danger(s) resulting from misuse, modification, physical damage, wrong charger, etc?

I like Luke's technique. Make a video of them acknowledging the danger right before they ride off into the sunset, or launch the bike into space.

 

[Rodney64]

to pack several of them next to each other and run them on the street is risky.

No it's not, they're not going to just suddenly explode
Again common sense - put them in something to protect them. And even people who foolishly just duct tape them to their frames rarely run into trouble even when crashing (there's been several stories of people dropping or grinding their packs into the road with no ill effects, though obviously this is asking for trouble)
Watch some of liveforphysics destruction videos and see what's REALLY required to make modern day lipo blow up.

It sounds like you've already made up your mind though...

Rodney, as a new user and in general I'd advise you to drop that voltage a little. Bulk charging to 4.2v/cell average means you're almost certainly going to overcharge some cells, even assuming you balance afterwards.

I took some failed packs apart. I really think they were made not to last a long time. Born to give a big bang and fail early.

And the cells can short. This stuff is for out in the field RC use.

Thanks Hyena for your advice. But I'm actually at the EV shop now and picking up my charger. It's already been set to that voltage.

Something that I will need to watch closely and Chris too.

 

[999zip999]

You are the bms so monitor and see how they float.

 

[Hyena]

I took some failed packs apart. I really think they were made not to last a long time.

What make and model ? If you're using shit no name ones from ebay then maybe. The ones I've been using on my commuter bike have been cycled twice daily most weeks for 2 years now without incident and still maintain near perfect balance.

I'm actually at the EV shop now and picking up my charger. It's already been set to that voltage.

There's a local place that sells elcon chargers over the counter ? Cool.
I've never used them but I'm sure they'd have a v adj pot. Chris can probably sort it out for you. I'd drop it to 100v neat, this gives you an average of 4.167v/cell. Without balancing, over time if not immediately some will end up 4.2v with some at 4.15v but it leaves a small safety margin for overcharging. If you're charging to 4.2v average some will end up closer to 4.25v which still isn't going to spontaneously combust as etriker would have you believe but it will shorten their life. That slight imbalance for discharge doesn't matter so much, assuming you've got cell level LVC monitoring the lowest cell will just determine you're overall pack capacity before it cuts out. But again, in keeping with the general guidelines for lipo use it's best not to run them all the way down anyway.

 

[Rodney64]

The way Chris has set up the method boards as soon as the first cell hits 4.2 the charger stops. Even if the pack was drastically out of ballance I'm not running any risk of any cell being charged over 4.2.

Until I start using this I really cannot comment any more. But one thing I have learned after reading this thread is that I will not be charging over night after seeing the result of that fire. Thanks Hyena for all your advise.

 

[amberwolf]

If you think this leaves too much to chance remember that for nearly 100 years cars have used oil or check engine warning lights and beepers and everyone knows that if that comes on then you have to stop the engine or risk damaging it (in this case the battery)

However, there have been people ignoring those warnings and driving until the engine blows up, too, even though they know better (like my mom driving a car that threw a rod, knowing that's what happened, until she was all the way home from almost 20 miles away, and the engine was destroyed, or a friend that decided to drive his aging car on a road trip from Phoenix to Los Angeles in high summer, starting out the trip with multiple "idiot lights" on, and actually catching the engine on fire about halfway there, in the middle of the desert).

So...warnings *can* work, but only if you can be bothered to pay attention to them. People don't even always pay attention to red lights at intersections, drive right thru and collide with cross traffic.... I'd say that's a frequent event, too.

But a hard cutoff might cause hazardous conditions depending on how and where they ride/drive. So there really isn't any good solution except to get people to learn to pay attention, without having to learn it the hard way (and some will not learn even then).

A full BMS would have prevented this incident. The wrong charger and a host of other mistakes would just result in automatic shut off.
The only people qualified to use lipo hobby packs unmanaged for ebikes are those who put the time in studying the dos and dont's...basically people who are on endless sphere frequently.
I'm eager to see a full bms designed for use with hobby king.

Except for a balancing feature, Methods' system already has everything needed for any RC LiPo type packs to prevent the kind of situation that happened here...except that if the user unplugs things (like the actual cutoff module) and plugs a wrong charger directly into the pack, it doesn't matter what BMS is on there. It would still damage the pack, possibly fatally, depending on the charger.

The LVC on Methods' is designed to either cut the throttle (or reduce it), and/or cut power from the pack itself, depnding on which module you use or which wya you wire it.

One thing to remember about the Methods unit is that it is intended as a last-resort HVC/LVC, simply to prevent the kind of failure this thread is about. It's not meant as an everyday cutoff system.

 

[etriker]

I took some failed packs apart. I really think they were made not to last a long time.

What make and model ? If you're using shit no name ones from ebay then maybe. The ones I've been using on my commuter bike have been cycled twice daily most weeks for 2 years now without incident and still maintain near perfect balance.

I'm actually at the EV shop now and picking up my charger. It's already been set to that voltage.

There's a local place that sells elcon chargers over the counter ? Cool.
I've never used them but I'm sure they'd have a v adj pot. Chris can probably sort it out for you. I'd drop it to 100v neat, this gives you an average of 4.167v/cell. Without balancing, over time if not immediately some will end up 4.2v with some at 4.15v but it leaves a small safety margin for overcharging. If you're charging to 4.2v average some will end up closer to 4.25v which still isn't going to spontaneously combust as etriker would have you believe but it will shorten their life. That slight imbalance for discharge doesn't matter so much, assuming you've got cell level LVC monitoring the lowest cell will just determine you're overall pack capacity before it cuts out. But again, in keeping with the general guidelines for lipo use it's best not to run them all the way down anyway.

The worst job of putting together a battery pack I have ever seen was one of these.
http://www.hobbyking.com/hobbyking/store/__14609__Turnigy_nano_tech_5000mah_10S_25_50C_Lipo_Pack.html

Where do you find high quality RC lipo ? Surely it costs more than the HK stuff ?

Considering the fact that they can cause a fire the poor construction suprised me.

That and shorted cells.

I would rather take my chances with something like this.

http://endless-sphere.com/forums/viewtopic.php?f=31&t=41161&p=610273#p610273

A123 stuff is the best. RC lipo the worst. Spend your money anyway you want !

http://www.emissions-free.com/catalog/c2_p1.html