Glad you dodged the flames! What a mess.

Thanks for the reminder that we can learn from this. I'll do my phone battery replacement in my garage, on a metal table with a glass-insulated top, with the door open and my ABC fire extinguisher, sand bucket, and water pail handy.

One of the hazards of dealing with any concentrated energy source in a car is that gasoline, natural gas, propane, and diesel can explode. Hydrogen can explode. Batteries can explode. It seems like fire suppression devices should be built into cars...

I think many/most of us know that Li Ion batteries have the potential to catch fire if the terminals or shorted. What I don’t think everyone may know is how quickly and how intensely they ignite.

Let me first say I’m not an amateur with electronics - been designing & building electronic equipment for about 65 years, and I am a competent tech. In the past, I have replaced cracked screens and bad digitizer pads in IPads a few times - not fun, but not rocket science either. You have to be knowledgable, careful and precise. So when my old IPad battery reached the end of its life (a curse on Apple for not making it easily replaceable), I ordered a replacement battery (since Apple would not replace it) and proceeded to disassemble the IPad this morning. Not for the faint of heart in that it requires softening the glue holding down the screen with s heat gun and then carefully prying it off. Then there are s multitude of timy ribbon cables to be carefully removed. All went well and I began removing the battery which requires softening the glue on the backside and carefully prying it off the case. As I was doing so, the plastic pry tool (supplied with the kit) must have punctured the flexible plastic case of the battery. Without warning, it erupted in flames, the like of which I haven’t seen since making rocket fuel in HS. Hard to overstate how quickly it exploded and the size of the conflagration. Smothering it didn’t phase it, and fearing I was about to lose the house, I grabbed one end (with flames shooting 1-2’ in the air), ran to the adjoining bathroom to my office and tossed it in the sink and turned on the water (wondering if there would be a further Li reaction with water). I was VERY lucky there was a bathroom a few feet away. The whole thing must have taken about 10 seconds including the 2 seconds of disbelief it was really happening. The result was scorched floor and carpet, a smoke filled room, fire alarms going off, black particles and soot everywhere and a badly shaken person. After this was over, I took a Xanax and drank a beer, and my heart rate is beginning to return to normal.

So what’s the point of this story? It is truly unbelievable how quickly and virulently a Li Ion/polymer battery can catch fire - gasoline is baby food in comparison. So make absolutely sure that you either use a plastic cap or other means to insulate the connectors of Li Ion batteries when you fly or carry spares. It’s easy to see how they could bring down an airliner.

I have Li Ion chargers for tools, cameras and IPads/IPhones, and I’m now rethinking all of them. The problem is that once the failure begins, it’s self perpetuating. I’m not aware that NiMH batteries in my PCs, cordless phones and rechargeable AAs have the same issue, but I’m going to do some research.

This from a company specializing in transport of LI ion batteries:

“Lithium ion battery fires usually occur after a battery has been damaged. Damage to a battery can cause a rupture in the membrane that separates the chemicals inside, causing a reaction that sparks a dangerous and self-perpetuating fire. Although these fires were poorly understood at first, analyses show a thermal runaway causes fire and explosion of the lithium ion batteries.

In any environment, small lithium ion fires can be put out with special fire extinguishers. Contrary to popular belief, Class D fire extinguishers are ineffective on lithium ion fires. Although they are labeled for use on metal fires, lithium ion batteries are a special case because they do not contain any actual lithium metal. The dry powder in Class D fire extinguishers will not slow a lithium ion chemical reaction.

Lithium ion battery fires are considered a Class B flammable liquid fire. A type ABC or BC fire extinguisher is effective against this type of blaze. These fire extinguishers interrupt the chemical reaction in the lithium ion battery, eventually stopping the fire.

Fire extinguishers designed to combat Class B fires are available in a few different formats. The best one is the dry chemical type because the extinguisher can launch the dry powder up to 20 feet horizontally. Carbon dioxide (CO2) and foam fire retardants are also effective, but their range is around half that of dry chemical extinguishers. Clean agent extinguishers are better for the environment and are less harmful to humans, so they are a better choice for close quarters like airplanes.

Surprisingly, water can be somewhat effective in dampening lithium ion fires, in part because it reduces the heat. However, chemical fire retardants are more effective, and any industrial or transportation setting that regularly has lithium ion batteries present should invest in more substantial fire prevention systems and protocols.”

1) the battery was almost completely discharged
2) heat is required to soften the glue, after heating, I would estimate the outside of the case was no more than 120 deg f (comfortable to touch)
3) puncture of case very likely and almost certainly the cause of the initial failure
4) impossible to short terminals ( battery still attached to MB connector)
5) my guess is that a puncture of the case/membrane by the tool or pulling the battery away from the case caused a failure of one cell which caused enough heat to penetrate adjoining cells and participate an escalating reaction. I don’t think just breaching the case would cause the failure - most likely the corner of the tool ruptured an internal membrane.

Takeaway? If I were designing with Li Ions, I would clamp them in place for easy removal/replacement - not glue them, then they would be easily and safely replaceable. I think it’s a poor design unless you never intend them to be replaced (which is apparently the case here).

Honestly, I don’t think heat was a factor except to the extent that I probably didn’t use enough to loosen the glue properly.. It’s an aluminum case, and the heat (from a hairdryer) was applied to the back of the case for well less than a minute with the heat source constantly moving. I placed my hand on the case periodically, and it was not hot. In retrospect, I wonder if prying around the edges may have also bent the battery (they are somewhat flexible), causing internal damage. I don’t know enough about the internal construction to understand the failure mechanism in more detail.

Also, in an age with pages of warnings, often absurd, in every product we purchase (don’t immerse the appliance in water), it’s interesting that there was no warning label of any kind on either the replacement or original battery. Although I usually make fun of these, it would have been appreciated as a reminder as to the danger in this case. Based on the warnings against inadvertent overcharging on this thread by several RC hobbyists, I am going to survey my home, identify all the LI Ion chargers, and place each in a large Pyrex dish away from any combustible materials and make sure there is a linked smoke detector near it. I’m also going to check all my camera batteries to determine if they are Li Ion, and make sure the spares have the plastic covers in place over the contacts. It occurred to me that I have several Fuji batteries loose in an accessory pouch without covers, they may not be LI Ion, but I’m certainly going to check - this incident definitely got my attention!