Hi Paul,
Interesting video, extreme abuse not normal use. But they weren’t expecting much, otherwise their protective gear would have been more than a woolen jumper as worn by the hatless man at the end. Full face shield, gloves, fireman’s jacket and hard hat for all within 20 m would have been prudent. The charging/ discharging bay was better. My old OHS officer would have suspended them all.
If you abuse your batteries enough they can fail in a spectacular way. Don’t be foolish and then complain.
BTW, attempting to let gas out of a nonventing battery could create a local short with the battery then self destructing. Don’t just jab a sharp object through the skin. If you don’t know how to do it and are making it up as you go then expect trouble.
One of the variables in all this is the charging rate and discharging rate. Some of the stories of batteries exploding when on charge are rather vague as to how the charging was set up. Even that video is silent on the details.
A group of model plane fliers wanting their batteries recharged as quickly as possible would be a good source of stories. Did they think doubling or quadrupling the recommended charging rate was safe, or just a way of getting it done quicker. 15 minute recharge at 20 amps, but at what risk? They don’t assess it and don’t seem to know what is safe and what’s stupid.
Some sources say that if the battery is rated at 4.2 AH, then you can charge it at 4.2 amps. How so? Is that a reliable guide or not? Can it be safely exceeded? Is it safer at half or a quarter of that rate?
FWIW I use a 1 amp charging rate on my 4.2 AH LIFEPO4 batteries, from a balanced charger. It starts at 1 amp but once the cells are each over 3.4v (target 3.6) the charging rate drops off and finally within .1v of target the current is less than 50 mA.
They were professional firefighters! If you want to use LIPO then that is up to you, My LifePo4 batteries even though they are the safest batteries, the documentation does state that you should make sure they are in protective packaging when transporting, this is more to prevent damage than safety. A LIPO is entirely different, puncture that whilst it is being carried in a rucksack and you will soon know about it!
It was interesting and so I didn’t want to be direct in my criticism but it seems I must.
Paid firefighters or not it wasn’t up to scratch for a professional test.
They weren’t fully kitted up.
There was no safety barrier or hazard signage and people in street clothes were wandering around quite close to the battery test. A big fail.
The only data presented was visual.
The thermometer readings might as well not been made other than the theater of it.
The samples were not equivalent in capacity. This I think is important.
There were no repeated tests to verify if this was normal performance. Even the tests done differed between battery types.
We learned that shorting batteries with a heavy conductor or charging it at a very high rate or striking it with an axe all result in the battery failing. No Nobel prize for that.
I think I’m done here now except to tell Andy that not only is duct tape now commonly of poor quality, so are weed killers, electrical insulating tape and super glue.
Tell me! It used to stick really well and a roll would last on a shelf for years. Now it comes undone in weeks and once you open a roll, it goes off and all the glue oozes out in months. Rubbish, bring back the tape from 50 years ago when I was a kid.
60 years ago when I was a kid, “insulation tape” was a woven material impregnated with black goo that got all over your fingers. Once applied, it set rock hard and was impossible to remove. I remember the revelation of PVC tape when I started my apprenticeship - but I agree even that is not what it was!
Don’t get me started on hacksaw blades…
Of course in those early Tesla car fires in road accidents, the problem was that in some cases the doors remained locked when the voltage was no more from the batteries and the people could not get out - poor souls!
But this is getting off the main thread. The point is that care with Lithium based batteries (of any type) is essential and once the batteries get to look like the one Colwyn has, it’s overdue to be replaced and now that the LifePO4 batteries have dropped considerably from the price that they were, for ease of usage with the 4S voltage around 13v and in many cases a built-in BMS in the battery itself, they would seem a good choice as a replacement.
The one that Andy put in the link to is now the standard battery that I take on activations.
Hi Paul, we have had reports on this reflector of LifePO4 batteries also “gassing up” and expanding, so I would not simply say that LifePO4 are the safest batteries - they may be “safer” than a LIPO but abuse a Lithium based battery be it Lithium Ion, Polymer, Ferric or any other mixture and you risk damage to it and possibly yourself. One could consider a SLAB battery safer than any Lithium battery for example but hit that with an axe and you will also have problems!
I have used LIPOs for years without issues, but I am very careful with them, they are only charged using a balanced charger and at a rate under the maximum charge rate specified.
Now that LifePO4 batteries are becoming available at a price only a little more expensive than LIPOs I believe they are a better choice. Previously when I could get a 4S 5 Ah Hardcase LIPO for €25-30 and an equivalent LiFePO4 battery was nearly €100 - the decision was different. At €35 for a 4Ah LifePO4 with built-in BMS, nowadays I think it’s worth the extra €5!
Even if it were metal, the reaction doesn’t raise the temp of the lithium high enough to ignite the gas, according to various demonstrations shown on Youtube and in my chem class at Berkeley. Is there something else in the envelope that gets hot enough?
Normally they don’t… overcharging, charging too fast or at too low a temperature can cause lithium metal to be plated onto the (usually) graphite anode. This can build up until it shorts the cell internally and… Fizz Fizz Boom
Yes… reactions between the lithium metal and the electrolyte can easily reach temperatures that cause self-ignition.
It is true that (at least in small quantities) Lithium + water is not self-igniting however by the time any lithium metal would be exposed to water in a battery fire there would be plenty going on to ignite the hydrogen produced
The reason LiFePO4 cells are so much safer is that the Lithium Iron Phosphate cathode material is considerably more stable than the (e.g.) Lithium Cobalt Oxide used in LiPo cells and can withstand higher temperatures without decomposition and consequent explosive results.
Although aimed at off-grid electricity storage a useful primer on how Li-ion cells are made up and work and modes of failure can be found at:
Richard,
You get a prize and I get to stand in the corner with a pointy hat on my head until after recess. All batteries use ions but not all batteries using lithium have lithium metal cathodes.
Lithium ion rechargeable batteries do not apparently contain a big sheet of lithium but a big coated aluminium sheet. The video I saw - a while back so can’t quote details - I now surmise was a disassembly of a non rechargeable lithium cylindrical battery not an 18650 rechargeable Li battery. I recalled a prohibition on using water on Lithium battery fires which made sense if metallic lithium was present.
The single use cells still use ions but like a lot of primary cells have a metal cathode. In the video I saw there was a lot of metal sheet that went fizz bang in water, rather like little bits of sodium does. Like a lot of videos it could have explained a bit more clearly what was happening but it had to be Li metal sheet.
Thin aluminium sheet burns fiercely in air once ignited but does not react exothermically with water.
The Zippy battery was always balance charged using an IMAX B6AC but slowly started to swell within months. It has been markedly swollen for 3 years, but finally burst as shown. I did wonder if it was a bootleg?
I have an 8 year old LiFePO4 3S for the FT817 (9.9v gives 4.7watts) which still works well. Also another 3S Zippy LiPo which is not too swollen! Currently using 3S LiPo salvaged from a defunct Dyson 21volt battery pack (I recall that dismantling the unit was exciting). All 6 cells were perfect when tested, so I have 3 spare if anyone interested? I charge each cell seperately, so guess it is always balance charged. Manage up to 5 activations on a single charge.
Rest assured, I will look for a recycling centre when shopping this afternoon.
My earliest LiPo batteries (about 2008 vintage) stayed hard as bricks until retired after ten years or so due to declining capacity. “Modern” LiPo’s seem to be prone to this “benign” swelling - all my recent purchases have exhibited it, becoming slightly squidgy with no decline in performance in what seems to be a self-limiting condition.
Yes indeed, my 2009 vintage 4AH LiPOs are still rock solid and in service. I used one for a couple of HEMA activations a few months back with no issues. Plenty of capacity still available when I changed over to one of the more modern Zippy batteries for the rest of the day. I really am wondering how long they will be able to provide power. I must admit to being reticent about replacing them… maybe I’ve spent too long activating in Scotland.
