Yet another Lipo Fire

im starting to have nightmares about the tabs on these lipos.
i think its really important to have them compressed well and enclosed so there is no movement inside the battery boxes

I've mentioned before in other threads that using silicone wire for ebike wiring is a bad idea. You should be using automotive or marine grade wiring. Silicone wire has terrible abrasion resistance.You can literally cut it with your fingernails.

I see the damage you are pointing to. But it's not certain sure that did not happen as the pack burned.

But I'm with you on this one, I think something shorted someplace, as the packs were able to bounce around in there some. Padding the bottom just put off the inevitable a bit longer. The packs, and the easily cut silicone wires were able to move around in there too much IMO.

I doubt I get much compression from it, but my starting point on lipo packs is always an extremely tight fitting coroplast box to give the packs some chance of standing the vibrations in the box. Then, inside the metal box, I use various soft materials that keep the coroplast box from doing excess movements inside the box or bag. Typically stiff foam materials, like fatigue mats, yoga mats, or more coroplast. Not too soft couch cushion foam.

Box em up good, as I've been saying since my first duct tape lithium battery in 2008.

The very first battery fire thread I ever saw was on a lifepo4 battery with a BMS. Loose and protected only by the duct tape, this battery shorted it's main wires on a sharp metal edge, and burned a converted to electric vespa scooter. That thread was in 2008 on V is for Voltage forum.

I'm sure what this thread needs is another opinion (NOT) but based on my very similar experience, bulk charging a puffed (i.e., probably internally failing) pack is a fire waiting to happen. I personally can't tell what caused that fire based on what is left. Could have been a short, could have been pack damage but again, bulk charging puffed LiPO is hazardous and in my opinion, the most likely scenario. The OP was smart or lucky enough not to do it in his basement or house, regardless of the cause.

Be careful out there. Unless you are Hindu or Buddhist, you won't be coming back for another shot.

in the first picture, on the right in the middle of that circle of wires you can see where one of the large conductors has all the insulation melted off and the strands are exposed. i feel that is the wire that shorted but all the other wires are similar size so they would also have the same current so why that one melted the insulation and not the others is the question.

that wire is on top of the sense wires coming from the pack underneath, yet those sense wires did not melt so is that pack the one that ignited? did that pack short to itself so only that pack initially overheated and went into runaway?

there are just so many wires, all the sense wires and cables and connectors rubbing against the metal. all inside a conductive metal box so that any place where the insulation wore down by rubbing on some sharp edge inside that steel box is where it could have shorted, and it would have to be two places where it rubbed through the insulation.

but if he was bulk charging with no protection it may be that the wire was just melted by the flames coming from the pack underneath it and the fire did not start from overheating following a short.

that was what i hoped we would learn from an analysis of this fire.

pdf said:

bulk charging puffed LiPO is hazardous

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If bulk charging is another way of saying over charging then I'm fully with you on that. The problem with puffed cells remains in any charging scenario though. Not just highly questionable one's. Puffed=Damaged. It also means there is movement within the cell. Cells often contain contamination that coupled with movement can lead to them puncturing themselves. A top 5 cause of cell fires I'm led to believe.

If I found a puffed cell I might keep using it carefully while replacements arrived. Some people just keep using them though. See: Darwin.




In the UK we have £1 shops. A good source for camping mats if anybody here needs packing materials.

friendly1uk said:

pdf said:

bulk charging puffed LiPO is hazardous

Click to expand...

If bulk charging is another way of saying over charging then I'm fully with you on that. The problem with puffed cells remains in any charging scenario though. Not just highly questionable one's. Puffed=Damaged. It also means there is movement within the cell. Cells often contain contamination that coupled with movement can lead to them puncturing themselves. A top 5 cause of cell fires I'm led to believe.

Click to expand...

I should be specific. Bulk charging without single cell monitoring can be hazardous; doubly so if a damaged cell is in the mix. From personal experience, abused packs tend to puff more. So to me, a significantly puffed pack is one that is probably damaged internally. Therefore, bulk charging a puffed pack is likely to lead to overcharging good cells to try to bring the average pack voltage up. So, yes, it is another way of saying overcharging is hazardous. No-one would knowingly overcharge a cell, but doing so while bulk charging is very easy if the cell voltages are not being monitored and a cell or more is damaged.

Sorry... I have been sorta "out of touch" with ES for the last few months... Define "scooter" for me please? (Used only once in this thread... Guess I am too lazy to poke around ES a bit... I am pretty sure the answer is here, somewhere...)
L

A scooter is an italian hairdryer made by vespa

Edit: There not just made by vespa though. Honda made lots, but in their defense, I must say, some did have pedals.

If its a sit up a beg ride with little wheels and step through platform for resting your feet on it's a scooter. The hairdryer noise is optional.

Ahhh! So it's a *converted* Vespa! Thanks for clearing up my confusion!
L

Are, I have edited late and deceived you. If it was a vespa I might of said it's for the best. He appears to of built something though. It looked good in his link. Not toasted either

Oh well, That will teach you to search lol

friendly1uk said:

I found a post listing the 5 likely causes of lipo fire, and an explanation of each on another forum: http://www.rctech.net/forum/electric-road/182219-understanding-lipo-fires-101-a.html
A bms should sort out 3 of them. Hard case batteries a 4th. Leaving internal shorts out of our control. Nice metal box

Click to expand...

Just read this link on the causes of lipo fires. Very useful, with a good explanation of what is going on during overcharge/overdischarge. Good stuff.

Sorry if I was confusing the issue, but I thought I wrote that pretty clear.

This thread is discussing a Lipo fire in a scooter. From the pics I presume the stand up scooter kind. Typically 100-1000w brushed motors, and sla batteries in a box built into the deck you stand on.

The VESPA, was discussing the first battery fire I ever heard of, in 2008. This fire happened with not only "safe" lifepo4, but also a bms. He converted an old gas Italian vespa scooter from gas to electric. He had a duct tape type, pouch cell, lifepo4 battery, not protected, rattling around a bit loose, in an area with sharp metal edges.

I'm not sure if the pouches got cut, or just the main wires, but either way enough sparks from a short set flammable pieces of the scooter on fire and it burned.

I just wanted to say, ANY battery carried in a way that allows a short can catch fire. BMS or no BMS. You can do a fun demonstration of this by getting a 9v radio battery and putting it in your pocket along with some pennies. Educational. You won't forget the experience.

All battery packs need a BMS. Its far too risky to charge without one. Human error can lead to fires.

dogman said:

Sorry if I was confusing the issue, but I thought I wrote that pretty clear.

This thread is discussing a Lipo fire in a scooter. From the pics I presume the stand up scooter kind. Typically 100-1000w brushed motors, and sla batteries in a box built into the deck you stand on.

The VESPA, was discussing the first battery fire I ever heard of, in 2008. This fire happened with not only "safe" lifepo4, but also a bms. He converted an old gas Italian vespa scooter from gas to electric. He had a duct tape type, pouch cell, lifepo4 battery, not protected, rattling around a bit loose, in an area with sharp metal edges.

I'm not sure if the pouches got cut, or just the main wires, but either way enough sparks from a short set flammable pieces of the scooter on fire and it burned.

I just wanted to say, ANY battery carried in a way that allows a short can catch fire. BMS or no BMS. You can do a fun demonstration of this by getting a 9v radio battery and putting it in your pocket along with some pennies. Educational. You won't forget the experience.

Click to expand...

No pal, you didn't confuse the issue. It was me thinking a scooter would be, well a scooter, not a childs toy. I forgot they are called scooters too.

www.scooter.co.uk/

I couldn't make sense of his pics, I just knew some effort was involved.

WOW... Currently slightly over 14,000 messages on ES that use the word "scooter"! Any links to a message/thread here that defines the word? Seen here:
http://www.finedictionary.com/scooter.html

1 scooter large black diving duck of northern parts of the northern hemisphere
2 scooter a sailing vessel with runners and a cross-shaped frame; suitable for traveling over ice
3 scooter a wheeled vehicle with small wheels and a low-powered gasoline engine geared to the rear wheel
4 scooter child's two-wheeled vehicle operated by foot
5 scooter a motorboat resembling a motor scooter.

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I nEVer thought for an instant we were referring to a "large black diving duct"! Yer kidding, right?

Hehe...

L

I'm sorry to mislead you so badly lock.

If you think this fire was bad for the owner, what about the poor duck. It was bad enough having them installed without this happening. All I can think of now is orange sauce lol

Yummm... Peking duck...

Lets get back OT?
L

there is nothing left here. the guy disappeared.