Li Ion discussion
Posted December 27, 2015 - 08:34 AM
- Oldford said thank you
Posted December 27, 2015 - 09:42 AM
There are stories that they have tiny pieces of foreign material (metals) in them and are shorting out the cells.
As long as your battery isn't a knock off Chinese imitation, you should be ok.
Your mileage may vary, do your own homework.
- LilysDad and Oldford have said thanks
Posted December 27, 2015 - 01:02 PM
Li-ion is kind of a general term, you need to get a little specific to weed out the safe from the dangerous under that heading.
Unfortunately lithium batteries are similar to motor oil in that the conversations quickly deteriorate into scientific arguments where big words and industry jargon buries any kind of personal experience or common sense.
Basically there are two types of lithium batteries these days, "LiPo" aka "Lipoly" which means Lithium Polymer, containing plastic in the mix, and then the general term "Lithium Ion" which has many different, metallic sub-chemistries, usually starting with Nickel, then including small amounts of metal like cobalt, manganese, aluminum added in. Sort of plastic electrolyte vs. metal electrolyte as i understand it, metal is safer than the polymer, also more expensive.
LiPo is the very dangerous "hobbyist" chemistry. It gives very high power-to-weight and is the cheapest to buy. It is used in high power applications like toy planes, helicopters, race cars, etc. Home hobbyists also buy these batteries in bulk for home-brewed transport devices like scooters and battery-powered race bicycles.
LiPo is dangerous b/c it can burst into a hot long-burning flame from simply over charging it, also over discharging it, also simply puncturing the battery. It is for speed freaks who need extensive charging and monitoring equipment, and who value speed and power, and low price, over safety. It has burned down many garages and houses from improper handling.
Most cheap Li-po batteries are made in china in hi-volume sweat shops and sold at super-cheap discount places so there isn't much quality control. They are "foil pouch" batteries that don't have much physical protection or monitoring circuitry built in, if at all.
Unfortunately the words "LiPo" and "Li-Ion" get lumped together, both in translation from Chinese vendors, and by the average consumer who is more used to calling batteries "car batteries" or "flashlight batteries" and never has to pay much thought to the chemistry inside. Also from sensationalist news stories looking for headlines on house fires.
Li-Ion batteries are used in most home-based electronics where no real thought or effort has to go into their care. The average Joe or Suzy Homemaker. Computers, cell phones, digital cameras, etc. Also the newer hi-end electric cars like Tesla and others. "Plug and Play" and limited risk, after all, the companies making these items don't want to face lawsuits. So they use safer battery chemistries.
Li-ion can be pouch batteries like in a cell phone, as long as they have metal and not polymer for the additives they are pretty safe and can withstand abuse. The technology keeps advancing with the added metals, earlier pure Cobalt batteries i believe were more dangerous, now with aluminum and manganese added they are more stable and powerful.
Bigger li-ion batteries are composed of multiple cells about the size of AA batteries that are spot welded together, with a BMS or Battery Monitoring System circuit board wired in that cuts power in case of a short. They range in size from a pack the size of a laptop or Makita battery to the big banks that power a Tesla car.
Unfortunately unscrupulous sellers from China are always out to make a buck and will try to sell the cheaper "LiPo" under the heading "Li-Ion" so that article above is true, you should pick your sources and determine what actual chemistry is used.
NCA, NCM are the current best chemistries of Li-Ion batteries. NCA has been used by NASA for years in its space stations. It means Nickel Cobalt Aluminum. NCM aka Nickel Cobalt Manganese has shorter shelf life and is cheaper. Then there is NiCO aka Nickel Cobalt an older chemistry that has been superceded by the safer blends like NCA/NCM. Other metals like titanium are constantly being tested as additives also.
Better quality Li-Ion batteries come from Japan (Panasonic) and Korea (Samsung), also Sony and LG, from outside China. There are reputable vendors in China who resell in bulk, but also crooks who will print "panasonic" or "samsung" on their junk batteries, adding to the mystery.
I'm no expert, i got into electric bikes last year b/c of injuries and had to learn a lot fast as they are so expensive. The BatteryUniversity link posted above is a good resource but just like BobtheOilGuy when discussing motor oil, there is a lot of stuff to wade through there, hope this helped break it down a bit, good luck
- olcowhand, MH81, Bruce Dorsi and 6 others have said thanks
Posted December 27, 2015 - 01:47 PM
Thanks OldFord, that was a good explanation.
- Oldford said thank you
Posted December 27, 2015 - 03:42 PM
I'm sorry i didn't address the initial question on hoverboards... don't really know what they are, googled them and saw fires. I'm guessing they use cheap, light, powerful LiPo batteries to get the things moving in the first place with 100+ lbs of human on board, and the boards themselves are going to bang around a lot, leading to failed connections, etc. So even if there is an onboard BMS if a wire falls off or something shorts, the LiPo batteries can easily thermal runaway, i'm guessing that is the problem, just more cheap chinese junk rushed to market imo again i know nothing about them just guessing... also if the average Joe leaves one charging overnight they can overcharge and thermal runaway, i'd never mess with LiPo myself, if you stick to the non-polymer Lithium batteries should be fine, think of all the times you leave your computer or phone charging overnight and no problems, still i try not to do that even with the good chemistries, any lithium battery can burn under the wrong conditions, always good to keep an eye on them when charging, good luck.
also oddly enough the chinese government only regulates electronics sold at home not overseas, so they dump all their cheap crap to the us and europe with no fear of lawsuits...
- olcowhand, MH81, Bruce Dorsi and 3 others have said thanks
Posted December 27, 2015 - 06:26 PM
- Oldford and Greasy6020 have said thanks