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The pictures do indeed speak for themselves! Goodness me. What are the statistics on lithium-ion battery failures? Are they dangerous full stop, dangerous in c

The pictures do indeed speak for themselves! Goodness me. What are the statistics on lithium-ion battery failures? Are they dangerous full stop, dangerous in certain scenarios (e.g. heat), or do we only hear about the failures when 99.9999… of the time they are fine as they are everywhere? Are all lithium-ion batteries created the same?

reisse 3y ago
Take a look at this guy's setup. He put consumer modem into a closed outdoor box under the sun without any ventilation or cooling whatsoever. Given there is enough sun to power the solar battery, I'd bet the temp inside the box is >70 degrees C. I am honestly amazed the whole setup lasted for so long.
- fbdab103 3y ago
  That is what you have to plan for when dealing with consumers. That someone will stick the device somewhere in the messy real world because it is easy. You have to engineer for people "holding it wrong" when failures can lead to loss of life.
- j45 3y ago
  With so many unused hotspots out there maybe it’s a few tweaks away. Battery management aside, those portable 12v fridges are great at using a fan to heat or cool
- ajvpowell 3y ago
  Author here. You are totally right, this whole thing was a self-confessed shoe-string hack job so it was far from ideal in any respect. I was pleased how long it lasted though and performed. Regarding temps, the modem itself, I seem to remember, never reported a temp higher than 55 degrees C. I don't live in a very warm place though...
bob1029 3y ago
I like to do a bit of napkin math when storing batteries. I don't care what the technology or marketing says. Think about it in terms of "A 33kWH battery roughly equals 1 gallon of gasoline". This is the most paranoid possible way to look at it, but it does help to establish some perspective. Energy is energy and if you don't really think it through, you may wind up with much worse than LTE modem/router fires. Tesla power walls are an example of something I could never install in my home due to this simple math. I would not be able to sleep at night knowing there is a chance they could go up while bolted to my home. I've got one of those EcoFlow batteries (2kWH) for emergencies, but I keep it on a concrete slab (protected from weather) outside my home. Go look at how a datacenter does their batteries if you want to get a sense of this very same paranoia at scale. All the DC-scale UPS systems I've seen typically consist of gigantic, low voltage cells installed in a manner expressly designed to deal with the worst case. I think the density of the energy is what is most dangerous in my mind. A whole room full of lead acid batteries might not be very portable, but its a hell of a lot easier to inspect room-scale components, prove they are safe, and deal with emergencies before they turn into catastrophes.
- fbdab103 3y ago
  If I am ever in a scenario where I could have a house-sized battery system, I intend to have a disconnected concrete shed dedicated for storing them. Seems like a simple mitigation which would make me feel significantly better about the situation.
- reisse 3y ago
  > Think about it in terms of "A 33kWH battery roughly equals 1 gallon of gasoline". This is the most paranoid possible way to look at it, but it does help to establish some perspective. Nah, that's the wrong way to think about it. Oxidation (well, burning) of lithium releases far more energy than the electric charge of the battery. Electric (dis)charge merely gives the initial heat to break structural integrity and set lithium on fire. And even then the problem is not in the amount of energy, but in that it's almost impossible to extinguish a lithium fire. And the fumes from battery are thick and toxic. > I think the density of the energy is what is most dangerous in my mind. A whole room full of lead acid batteries might not be very portable... Nah again. Lead-acid just does not burn so spectacularly. And about the energy density - filled fuel tank of a regular car has much higher energy density than Tesla battery, but is significantly harder to ignite, easier to extinguish, and when burning, releases the energy slower.
  - George83728 3y ago
    The worst case scenario with a lead-acid battery is some manner of electrical fault leading to electrolysis in the batteries, releasing hydrogen and oxygen gas which subsequently may cause a very violent explosion. I've never heard of a house blowing up like this, but it has happened with submarines.
    - Tool_of_Society 3y ago
      Long ago a friend's car battery exploded. The car was an early 70s chevy nova so there wasn't much in the way of electrical system to check. Everything was good and the next battery lived +5 years with no changes. Always figured there was some minor defect or something that caused the battery to start emitting hydrogen.
fer 3y ago
> What are the statistics on lithium-ion battery failures? Are they dangerous full stop, dangerous in certain scenarios If you wanna get more paranoid: https://www.reddit.com/r/spicypillows/ https://www.reddit.com/r/spicypillows/ Jokes aside, hard to say, but it's mostly scenarios. Some batteries have proper venting (or puffing), protection circuits and sensors to prevent thermal runaway, and they are very unlikely to fail catastrophically, they would stop working before, generally. Now those take more space, so such features are often offloaded onto the PCB designers to make them fit, and you may trust them more (or less) than the battery manufacturer. More or less the same can be said about the charging circuit, and how it might handle low voltage or trickling/stop charge. Personally I've seen flashlights that burn through the 18650 without respecting the minimum voltage whatsoever, and that would put 5V to charge. There a proper battery will refuse to charge or just die, but an unprotected one might catch fire. As anecdotal data, after dozens and dozens of devices, I've only owned two batteries that became spicy (without catching fire), a Chinese-brand laptop and a cheap quadcopter battery.
kristopolous 3y ago
> Are all lithium-ion batteries created the same No They have different chemistries with different characteristics. Some are safer than others See here https://en.m.wikipedia.org/wiki/Comparison_of_commercial_battery_types https://en.m.wikipedia.org/wiki/Comparison_of_commercial_bat... Beyond the actual chemistry there's regulators of various quality and strategies that can be found in many modern battery packs. I'm not a professional in battery manufacturing but I'm sure there's somebody around here who is that can give more details

reisse 3y ago

Take a look at this guy's setup. He put consumer modem into a closed outdoor box under the sun without any ventilation or cooling whatsoever. Given there is enough sun to power the solar battery, I'd bet the temp inside the box is >70 degrees C. I am honestly amazed the whole setup lasted for so long.

fbdab103 3y ago
That is what you have to plan for when dealing with consumers. That someone will stick the device somewhere in the messy real world because it is easy. You have to engineer for people "holding it wrong" when failures can lead to loss of life.
j45 3y ago
With so many unused hotspots out there maybe it’s a few tweaks away. Battery management aside, those portable 12v fridges are great at using a fan to heat or cool
ajvpowell 3y ago
Author here. You are totally right, this whole thing was a self-confessed shoe-string hack job so it was far from ideal in any respect. I was pleased how long it lasted though and performed. Regarding temps, the modem itself, I seem to remember, never reported a temp higher than 55 degrees C. I don't live in a very warm place though...

bob1029 3y ago

I like to do a bit of napkin math when storing batteries. I don't care what the technology or marketing says. Think about it in terms of "A 33kWH battery roughly equals 1 gallon of gasoline". This is the most paranoid possible way to look at it, but it does help to establish some perspective. Energy is energy and if you don't really think it through, you may wind up with much worse than LTE modem/router fires. Tesla power walls are an example of something I could never install in my home due to this simple math. I would not be able to sleep at night knowing there is a chance they could go up while bolted to my home. I've got one of those EcoFlow batteries (2kWH) for emergencies, but I keep it on a concrete slab (protected from weather) outside my home. Go look at how a datacenter does their batteries if you want to get a sense of this very same paranoia at scale. All the DC-scale UPS systems I've seen typically consist of gigantic, low voltage cells installed in a manner expressly designed to deal with the worst case. I think the density of the energy is what is most dangerous in my mind. A whole room full of lead acid batteries might not be very portable, but its a hell of a lot easier to inspect room-scale components, prove they are safe, and deal with emergencies before they turn into catastrophes.

fbdab103 3y ago
If I am ever in a scenario where I could have a house-sized battery system, I intend to have a disconnected concrete shed dedicated for storing them. Seems like a simple mitigation which would make me feel significantly better about the situation.
reisse 3y ago
> Think about it in terms of "A 33kWH battery roughly equals 1 gallon of gasoline". This is the most paranoid possible way to look at it, but it does help to establish some perspective. Nah, that's the wrong way to think about it. Oxidation (well, burning) of lithium releases far more energy than the electric charge of the battery. Electric (dis)charge merely gives the initial heat to break structural integrity and set lithium on fire. And even then the problem is not in the amount of energy, but in that it's almost impossible to extinguish a lithium fire. And the fumes from battery are thick and toxic. > I think the density of the energy is what is most dangerous in my mind. A whole room full of lead acid batteries might not be very portable... Nah again. Lead-acid just does not burn so spectacularly. And about the energy density - filled fuel tank of a regular car has much higher energy density than Tesla battery, but is significantly harder to ignite, easier to extinguish, and when burning, releases the energy slower.
- George83728 3y ago
  The worst case scenario with a lead-acid battery is some manner of electrical fault leading to electrolysis in the batteries, releasing hydrogen and oxygen gas which subsequently may cause a very violent explosion. I've never heard of a house blowing up like this, but it has happened with submarines.
  - Tool_of_Society 3y ago
    Long ago a friend's car battery exploded. The car was an early 70s chevy nova so there wasn't much in the way of electrical system to check. Everything was good and the next battery lived +5 years with no changes. Always figured there was some minor defect or something that caused the battery to start emitting hydrogen.

fer 3y ago

> What are the statistics on lithium-ion battery failures? Are they dangerous full stop, dangerous in certain scenarios If you wanna get more paranoid: https://www.reddit.com/r/spicypillows/ https://www.reddit.com/r/spicypillows/ Jokes aside, hard to say, but it's mostly scenarios. Some batteries have proper venting (or puffing), protection circuits and sensors to prevent thermal runaway, and they are very unlikely to fail catastrophically, they would stop working before, generally. Now those take more space, so such features are often offloaded onto the PCB designers to make them fit, and you may trust them more (or less) than the battery manufacturer. More or less the same can be said about the charging circuit, and how it might handle low voltage or trickling/stop charge. Personally I've seen flashlights that burn through the 18650 without respecting the minimum voltage whatsoever, and that would put 5V to charge. There a proper battery will refuse to charge or just die, but an unprotected one might catch fire. As anecdotal data, after dozens and dozens of devices, I've only owned two batteries that became spicy (without catching fire), a Chinese-brand laptop and a cheap quadcopter battery.

kristopolous 3y ago

> Are all lithium-ion batteries created the same No They have different chemistries with different characteristics. Some are safer than others See here https://en.m.wikipedia.org/wiki/Comparison_of_commercial_battery_types https://en.m.wikipedia.org/wiki/Comparison_of_commercial_bat... Beyond the actual chemistry there's regulators of various quality and strategies that can be found in many modern battery packs. I'm not a professional in battery manufacturing but I'm sure there's somebody around here who is that can give more details