If you thought lipo fires were all hype, read on

[Former Member]

[This posting has been removed]

[Tim Mackey]

Do NOT chill them whatever you do....honestly all packs will perform much better when nicely warmed - I even had my missus make me a little "quilt" to keep mine in so they are kept warm. LiPos can stand getting pretty darn warm before they start to suffer.

[Tim Mackey]

Ron. I am currently ( dreadful pun not intende ) finishing off an article for the magazine on Lithium batteries, and therefore cannot give too full an answer to this issue - "rules" mean that pubication in the printed magazine precede articles appearing on the forum, so please look out for said article over the coming months.

Meanwhile here is a sneek extract of one or two critical points regarding temperatures and cell life /efficiency

• Cells should be stored @ 50% capacity in a dry cold place between 0 and 15º C.

• A pack charged to 100% should not later be then cooled below room temperature. Therefore if planning to take a pack out into very cold weather, a charge to 90% or so of capacity is advisable. Then, I usually transport them in a warm “blanket” or similar, so that they are at best capacity just prior to flight.

• A nice and efficient working temperature for your packs is around 40º C

• If cells are “cut off” at no lower than 80% maximum depth of discharge and never charged above 90 % of full capacity, their life cycle may be almost doubled. Lifespan is certainly maximized if you do this and if not discharged continuously at currents that cause the battery to go above 65ºC maximum.

HTH

[Erfolg]

I have read that the problem has been put down to an exploding Lipo.

I can believe that the lipo initiated a fire, but surely not all the damage shown. Was there petrol or glo fuel involved?

When the Sony portable PCs caught fire there was no mention of explosions from what i recollect. How do all these Li-ion batteries go on in portable tools and the sports car that was recently featured on TV. Are these potential product liability actions waiting to hit the USA court system?

But then again if what happened  is the equivalent of standing a plastic can of petrol adjacent to an electric fire, it is a warning to me that I must be careful and remind myself that I need to be vigilent.

I remember the often quoted cases of Nicads doing real damage by exploding, I also know of a case where a pb acid battery exploded as some one used a lighter to see if the cells where gassing during charging. In these instances it was behaviour that was less than cautious, and not in occordance with recommendations that lay at the root of the incidents.

I just hope that my gut feeling that handled responsibly, the risks are acceptable and no greater than other products i use, is correct.

Erfolg   

[Tim Mackey]

Yes but the point is there has been no word as to what caused the LiPo to "explode". These things simply do not self ignite or otherwise explode on their own accord.... even though surprisingly this chap claims to have witnessed such an event - also interesting that he mentions certain brands "have given him trouble in the past" and laso there is some talk of possible incorrect balance plug connections / wiring.

My bet is that as the battery was under charge, the settings were wrong, despite his claims that they were not.

How could he be 100% sure- especailly as the evidence went up in smoke.

On a positive note...sounds like plenty of folk are helping him out with replacements!

[Erfolg]

Many years ago I visited Cognac Hennessey. It was explained that only certain fork lift trucks were allowed to work, as electrically powered devices had an unacceptable risk of producing a spark. As the atmosphere was heavy with alcohol fumes, a risk of explosion was very real. This had occurred elsewhere.

An explosion would have been caused by exploding alcohol vapours not the electrical spark, this being the initiator.

Similarly whilst working a various chemical producers, the risk of fire and explosion was very real in some locations. The electrical equipment, motors, switchgear etc. were manufactured to particular standards. The same was true of hand tools, alluminium and steel combinations were avoided. All these things were done to ensure that no fire or sparks could act as initiators to a major fire or explosion.

Being a garage there is a possibility that many other materials could be stored together. Typically Cellulose thinners, modelling dope, white spirits, glow fuel all these common materials if present have great potential to cause a significant fire.

Could this be a case of pointing a prejudicial  finger at a bit player?

I am just removing my white spirit to the garden shed, thinking of doing the same with the dope and cellulose thinners.

Erfolg  

[Erfolg]

The more I have thought about these events, the less credible I find it, to see a Lipo as an explosive device. That is as a mini bomb. Yes they can puff up. But if the package burst, I would be suprised if it made a large pop, never mind a bang as in a balloon.

We all know that alluminium can be made to release a large amount of energy, as in rocket motors Or that magnesium can burn with with great intensity. But to get them to do these things does take some effort and engineering. I have never seen an Audi A6? spontaneously burn like a rocket, or a Volkswagen engine catch fire because the engine parts started to spontaenously burn.

Given the potential of Hydrogen Peroxide, it is a small wonder that all these blonde haired ladies have not had there hair catch fire during treatment.

What is really required is a contribution from a Chemist (preferably  qualified), who can tell us about mole energy values of the components, relate it to temperature, pressure etc. In other words Gibbs free energy.

I bet that the energy available from our sized lipos, both electrical and the constituants, is nothing like that of a 50mml bottle of Meths, Petrol, White Spirits, etc, being far lower. That is partially why we struggle to emulate ic engine performance

If I am wrong the Airports need to stop us taking on board aircraft ,Portable Computers, Mobile Phones etc. and stop worring about liquids.

I do believe there is the potential to catch fire, but explode like a bomb, mmmmmmmm 

If you tell me that if contents are exposed to air, there is the potential for an exothermic reaction, I might beleve it. Althoght unless the breach is large the in leakage of air would probably be to small to sustain a significant rate of reaction.

I seem to remember some one driving a nail through a Lipo to demonstrate there robust nature, or ma i mistaken?

Very Sceptical

Erfolg