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Lithium-ion batteries?

Old 01-11-24, 01:41 PM
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Originally Posted by Duragrouch
In one of my past lives, my work involved EOD (bomb disposal) robots. Came time to modernize and upgrade the power densities, the lead-acid batteries were replaced with Nickle Metal Hydride; Lithium Ion batteries had long been on the market and offered even greater power density, but there was hesitancy to make a potential bomb from a bomb-disposal robot.

I do not yet own an electric bike, but am happy for the Li-Ion cells, their high power density, their range. But given the size of those batteries, I would never charge them on the bike, I would obtain a STEEL (not aluminum) charging box that could totally contain any fire, explosion, and excessive heat, and always charge the battery in the box, with the box sitting on something fireproof, like bricks or a concrete floor. A bit more hassle, but a lot more safe. It would be nice if the battery were internal to the bike if the bike itself could contain a fire, but a frame from aluminum or carbon-reinforced-plastic, no. This is why Boeing had to replace the box holding lithium emergency batteries on the 787, from aluminum, to steel or titanium (I forget which), because aluminum did not adequately contain two separate fires.

My phone and keyboard use lithium batteries. Despite their much smaller size, I never leave anything on a charger unattended.
Well, it sounds like you're going to spend some MegaBucks to get a charging situation that meets your wants. Your approach seems to assume a fire will happen and you want to contain it; in other words, no faith in the manufacturers or 3rd party certifiers.
I would suggest shopping for only eBikes that have 3rd party certified battery packs and chargers. Some eBikes now have their power systems certified as well. (Aventon, for instance) Quality eBikes' batteries have a BMS (Battery Management System) built in which keep fires from happening. Ditto for the charger.

Check my recent thread on safety certifications for more specifics: Safety Certifications
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Old 01-12-24, 08:21 AM
  #77  
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Originally Posted by Smaug1
Well, it sounds like you're going to spend some MegaBucks to get a charging situation that meets your wants. Your approach seems to assume a fire will happen and you want to contain it; in other words, no faith in the manufacturers or 3rd party certifiers.
I would suggest shopping for only eBikes that have 3rd party certified battery packs and chargers. Some eBikes now have their power systems certified as well. (Aventon, for instance) Quality eBikes' batteries have a BMS (Battery Management System) built in which keep fires from happening. Ditto for the charger.

Check my recent thread on safety certifications for more specifics: Safety Certifications
Oh I totally agree with your recommendations, same as the government. My feeling is even the best systems can fail; Boeing has really, *really* high quality specs on their lithium battery system on the 787, and even they had a runaway failure. Thus, on something this critical, where I could not charge the battery on the bike in a fire-safe area, I would charge the battery alone in a fire-safe box. Even a small lithium battery in contact with flammables could start a fire, but those large assemblies for serious power output, they just turn into bombs when there is a big charge failure, they don't just burn, they actually explode, not like high explosives, but enough to send flammable igniters many feet. Serious failure-modes require layers of protection; Quality batteries with good failure detection and shutdown modes, AND a backup of containment if that fails. At the very least for now, until more is known over time.

One place in Asia, is pioneering a system, where no one charges at home; You buy the bike, and pay for battery lease; You run the battery until low, then swap it out at a commerical center for a fully charged battery, faster than filling up a gas tank, 30 seconds and you're gone. That's a really great system. However, in my city, one brand of rental e-bikes has that kind of a system, a big battery in a compartment under the seat, and they are a frequent target of theft, thieves prying or sawing open the compartment to steal just the battery.
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