3kwh 20s40ah HK lipo going up in flames while charging.

[liveforphysics]

I would love to know what you think any amount of firefighters or army guys or anyone else would have done better.

Duh
He would have pulled out the 35lbs of powdered copper he keeps in his backpack for lithium fires



-methods

Lol.

[Stevil_Knevil]

Mounting lipo packs with 5mm bungee cord would allow flaming packs - (as they melt through) to be ejected off the side(?)..

..not unlike a fuse..

[El_Steak]

My sympathies, that's a lot of Lipo to see going down in flames. Hopefully you'll be able to salvage some of it.

As the other said, LVC boards (Methods supplies them for cheap) are the way to go.

For a 20s pack, a duo of 1000W 10s RC chargers on separate power supplies is also a good way to charge with HVC cell-level protection and balancing.

[amberwolf]

A few of my bikes have the packs hard mounted and i worry some day that this will happen and i got no way to quickly remove the pack to let it burn....... *ponders a quick release method........

A little thermite or similar, mounted around the edges of the pack mountings. If the pack burns, it sets off the thermite and then you just knock the thing out of the frame.

Assumign it doesn't melt your frame first....

[Stevil_Knevil]

Bingo! Thermite enhanced bungee cord

[Lebowski]

I have brand new out of the box 5s 5Ah zippy packs for my bike. I'm ballanced charging using a iCharger1010+
to 4.1 V. For discharge I have beepers which observe every cell and are set to go off at 3.6V . Max charge
rate is 1C, discharge 1.5C

I am a Lipo newbe so, am I treating my packs right ? Would a fire like this be likely ?

[amberwolf]

Only if you take more Wh out than you are putting in, and then recharge them. Use a wattmeter to monitor charge and discharge, and cell-level LVC / HVC, and you shouldn't have any issues, once you've established that the packs are all good to start with.

[neptronix]

I have brand new out of the box 5s 5Ah zippy packs for my bike. I'm ballanced charging using a iCharger1010+
to 4.1 V. For discharge I have beepers which observe every cell and are set to go off at 3.6V . Max charge
rate is 1C, discharge 1.5C

I am a Lipo newbe so, am I treating my packs right ? Would a fire like this be likely ?

That is being extremely nice to them.
You should be fine, unless you have a pack or 2 in there that is a *real* oddball.

I suggest that since you have the same charger setup as me, you check out logview, it works with the iCharger for charge / discharge graphing.

http://www.logview.info/vBulletin/

[amigafan2003]

A few of my bikes have the packs hard mounted and i worry some day that this will happen and i got no way to quickly remove the pack to let it burn....... *ponders a quick release method........

Yeah - I had my 63v10ah lipo pack hardmounted in the frame in an alloy box. I now have it sitting in an ezee bag velcro'd to the rear rack. I can rip it off the bike real quick if required.

[dogman]

About how I treat my packs too Lebowski, except I charge to 4.2v I don't have a good reason to discharge them deep, so I rarely do. Most of the time I stop at about 3.8v

The key things are don't overdischarge, then recharge them in a place where fire would be a bummer. I've really heated up some packs overdischarging them by mistake, but no fires when I did that a to a few times.

I think I will always prefer charging my RC lipo off the bike. That's when the fireworks are likely, or in a crash or other event that shorts them.

[miuan]

I bet that if you had a meter on all of the individual banks you would have seen that the damaged banks where showing a much higher voltage than all the rest.

I recently tested one of these hardcases specifically to find out what happens to 0V cells that either wouldn't hold charge anymore, or were just puffed but behaved normally. Upon 1.5C charge, the bad cells held a voltage of about 2V while charging, but dropped back to zero in a matter of seconds after I stopped the charge. So each cell was dissipating 15W heat, but eventually they'd start holding some of the charge I gave them, and got to 3.5V by the time the good ones in series already got over 4V. The weak cells were dangerously hot and puffed, but didn't pop. Then I let them sit and watched ALL of them lose voltage, the leakers and keepers alike. About 10mV per minute.
It seems that using these cells would soon result in a situation where they'd get to 0V while others were fully charged, thus overcharging all the other cells, or popping the weak cells from heat. Though they proved to be quite heat resistant, an enclosed pack of stacked cells would've helped them pop much sooner.

$3 for one of those cheap ass Hobby City beepers - buy 3 or 4 of those and plug them in.
That will save your ass next time
Just dont leave them plugged in all the time (while storing)

While they're handy little devices, it's not a good idea to slap them on all the riding time, then bulk charge. They tend to unbalance cells quite badly. Treat and know your cells so you can trust them and not just worry all the time.
I've had much more luck with conservative pack level LVC and cell level monitoring before and during charging (about mid charge).

I also use these on all my (and friends') builds.
http://www.ebay.com/itm/Digital-Voltmet ... 0904901912
...and stop at 3.7V per cell unloaded.

[Lebowski]

About how I treat my packs too Lebowski, except I charge to 4.2v I don't have a good reason to discharge them deep, so I rarely do. Most of the time I stop at about 3.8v

The key things are don't overdischarge, then recharge them in a place where fire would be a bummer. I've really heated up some packs overdischarging them by mistake, but no fires when I did that a to a few times.

I think I will always prefer charging my RC lipo off the bike. That's when the fireworks are likely, or in a crash or other event that shorts them.

I had a look at the graphs neptronix posted in another thread and had the impression there was not a lot
of Ah to be had between 4.1 and 4.2 ? I chose 3.6 as the underlimit, the beepers measure when the pack
is delivering upto 1.5C so the 3.6 is my idea of 3.7 but take away 0.1 due to the current drawn (the beepers
only have a resolution of 0.1V for the alarm, else I'd have gone with 3.65)

[whatever]

cell logs when riding will show duds
I charge in lots of 24v packs also, much safer.

[Ypedal]

http://www.youtube.com/watch?v=5F3hWc0x1B8



In that video, the cell on the left did not burst into flames, even tho it was over-discharged and puffed and vented gas, but it was only 2 cells.... run a 100v pack and do this... it will release flames.

[kfong]

Bummer, that's a lot of batteries to loose. For those who have batteries mounted into the frame. You should enclose them in metal or carbon fiber with a vent. That way they can burn out without much damage to the bike or surroundings. I never bulk charge if possible, too many unknown variables such as damage to packs after a ride, over discharging, loose connections, wrong charging voltage, bad cells, broken wires. A good RC charger will at least address some of these problems by monitoring the packs through the balance ports. I like the Hyperion chargers, very well designed and reliable. Draining your packs too close to the knee is going to give you unbalanced packs, so balance charging afterwards is a must. If something is wrong, the algorithm on the charger will stop the charge process and indicate the problem. A good way to double check during the charge process with the Hyperions is to look at the balance voltages. It even gives you max difference. Most lipo fires happen during the charge process, since you are forcing energy into the pack vs removing energy during use.

Was any packs saved? Seemed unlikely with such big packs.

[Ypedal]

nevermind the pack... how's the bike ?..

[neptronix]

About how I treat my packs too Lebowski, except I charge to 4.2v I don't have a good reason to discharge them deep, so I rarely do. Most of the time I stop at about 3.8v

The key things are don't overdischarge, then recharge them in a place where fire would be a bummer. I've really heated up some packs overdischarging them by mistake, but no fires when I did that a to a few times.

I think I will always prefer charging my RC lipo off the bike. That's when the fireworks are likely, or in a crash or other event that shorts them.

I had a look at the graphs neptronix posted in another thread and had the impression there was not a lot
of Ah to be had between 4.1 and 4.2 ? I chose 3.6 as the underlimit, the beepers measure when the pack
is delivering upto 1.5C so the 3.6 is my idea of 3.7 but take away 0.1 due to the current drawn (the beepers
only have a resolution of 0.1V for the alarm, else I'd have gone with 3.65)

My graph is deceiving. Those cells were charged up to 4.15v or so.

I avoid charging above 4.175v/cell average though, because i like to bulk charge 99% of the time. You do need a little room for error.