Little-Acorn

There was an explosion in a FedEx office this morning (Wednesday, April 14) here in San Diego, maybe four miles from where I live. Apparently a box with some kind of lithium batteries in it, went bang. No one was hurt.

First I heard of it was an announcement on the local station (KOGO 600 AM), which said that a "Lithium Ion" battery had exploded. I looked into several other reports, all of which simply said it was a "Lithium battery". I called the station and asked if they knew for sure it was a "Lithium Ion" battery, and told them the differences between "Lithium Ion" and "Lithium Polymer". Told them I use the former in e-bikes, mostly because they are the SAFE version of lithium batteries that don't explode, while occasionally LiPoly batteries do. Asked them not to call it a "Lithium Ion" battery unless they knew for sure that's what it was.

I have a hunch it was a LiPo - we all know how unstable those can be. Hopefully they will take my advice, but who am I.

I still haven't seen any reports of this explosion that calls it one way or the other, except for KOGO's verbal report.

Can some of you folks give the station a call, and ask them to verify exactly what kind of battery it was? Lithium-Ion (aka LiFePO4) or Lithium-polymer? And point out to them the differences in safety between the two?

KOGO's News Tip line is 858-560-6671. Their call-in listener line is 800-600-5646.

All we need is for shipping services to ban "Lithium batteries". I wouldn't blame them for banning LiPo's, they can be dangerous, though explosions like this are rare. But we use Lithium-Ion batteries because they are the safe ones, that DON'T explode!

------------------------------------------------

Another report can be read at https://www.signonsandiego.com/news/2...xpress-office/

Some of the text:

nwmtnbkr

Acorn,

LIFEPO4 is not the same as Lithium ION or Li-ION. They have different chemistries. LIFEPO4 is safer than traditional Li-ION and doesn't have the same issues with fire and explosions that Li-ION and LIPOLY share (although Li-ION isn't quite as volatile as LIPOLY). The cathode in LIFEPO4 is Iron Phosphate. The cathode in Li-ION is either Cobalt Oxide or Magnesium Oxide. Li-ION. like LIPOLY, can pack a lot of power in a small package and, therefore, is used in consumer products that require decent power but small dimensions, such as cell phones, laptops, etc. There are numerous reports of Li-ION batteries catching fire or exploding.

Little-Acorn

Yep, guess I didn't use the names right. Though I've frequently heard LiFePO4 batteries referred to as "Lithium Ion".

But my point stands. I wish the media would correctly identify the kind of battery that went bang. Was it a Lithium Polymer, or LiFePO4, or....??

It would also be nice if they pointed out that certain battery chemistries have more instability than others, the latter being quite safe.

nwmtnbkr

I don't think the media or general public cares about the distinction between battery chemistries. It's something people in industries that handle them for any reason must focus on since US and international (UN) regulations require that they be handled as hazardous material. I wouldn't get too frustrated about it.

chevy42083

Yup... most don't know the difference, so most won't care. Wasted air time.
I know some basics of LiPo from running R/C cars, but couldn't tell you anything about them compared to any other lithium battery.

They only said lithium to distinguish it from a Duracell/energizer in someones office/clock radio. That was the extent of the need to explain the battery.

Avenir

Reading all the posts about Lithium Polymer is getting me somewhat concerned. The two electric folding bikes we have paid a downpayment on have them. Here are the specs on it:

7 Speed Shimano Gears
Alloy aluminum handlebars, stem and brake levers
LED rear light
PP fenders with gel seat
Folding pedals
36V/9-10 Panasonic lithium battery with 350W front motor. Charging times 2-3 1/2 hours. Dual volt charger included
Speed under power 28-30 km/hr. Range 50-80 km per charge
Manual, pedal-assist and full throttle available to use
Alloy aluminum V brakes, frame and forks; Single walled alloy rims with stainless spokes
Capacity: 115 kgs
We are buying the bikes ready made, come from a Canadian Distributor whose prototype picture (that they emailed to me) has the name Li Cheng on it. I googled Li Cheng and found it to be a manufacturer from China. Do I have anything to be worried about? What safety precautions do I need to take with these?

dumbass 

I wouldn't over react to this. There are billions of batteries made, used and charged every year and damn few of them ever have a problem. As for where the bike or batteries are made I have bad news for you..........most bikes and batteries just like everyrhing else these days are made in China. So unless your going to stop buying almost everything your going to buy it from China like it or not so just have fun with it. By the way it's been like this a lot longer then most people know about.

CowtownPeddler

There are two ways to make a cell go like that, and since it was quite small an explosion, I am quite surprised.

After watching the videos of Lithium cells go, you can overcharge them (fire), or you can puncture them. They don't just explode on their own. You can also set them on fire, and then they go. Either way, with my cells, I expect a chain reaction - one will go and take the others with it.

I got mine across the border via Fedex. It wasn't cheap, but they were packed quite well and clearly marked.

There is much more to this story, like they fell off the conveyor - cracked and off they went. Notice that staff were nowhere near and there weren't any injuries reported.

I'd also say that they were much smaller than my 20Ah cells - showed them off to an RC shop dude here and he couldn't believe his eyes. Good bet these were small cells as well - my package weighed in at just over 20lbs.

I estimate each has the potiential of 7 road flares, so the pack would be like 84 road flares going off, all at once and in a bundle. I do hope I never get hit by a car with an almost empty gas tank or worse.....

I joke about it, but safety is all about never assuming anything and ensuring you are aware and choose correctly to identify and minimize risk.

I have named my bike "Pinto" after a favourite Ford car which is notorious.

Avenir

Thanks for the replies to my concerns. I do feel a bit better about it all. I will try and make sure I never overcharge the batteries, like setting a timer when to unplug. I would however hope that there is some sort of built in protection in these things that they do not overcharge even if plugged in too long, whether that is part of the controller? or what? I am really in the dark as to the mechanics of these things. I understand the bicycle, but as soon as it is electric I am baffled. That is where the hubby comes in! (some knowledge but not particularly with respect to ebikes, but fixing cars etc.)
Cathy

dumbass 

The protection will be in the charger. Be sure to use the correct charger (the one that comes with the bike to start). Never charge when you are not home and I try to never charge when I go to bed. You should never charge on a flamable serface and like all batteries charge in a well vented area and don't charge cold batteries. Most chargers will tell you not toexceed a certain amount of time on charge. There are several and/or different reasons for this. Bottom line follow the directions and you should be fine. While this is new to you it's not "new". But like everything you should always take some common sense procations as I listed above.

CowtownPeddler

Well, the guys do have a good point about charging in a well ventilated and clear area (preferrably away from the house)... I would say at least initially until you gain confidence in the charger, etc.

If you are going to use a timer, I would say that it's better to set a personal alarm and be sure to go check the charger and cells. If it's close to done, then decide.

I guess the argument for a CellLog is solid for audible alarms on overcharge and discharge. If your battery does not have the correct connector for it, you can manually add it, or get someone to. It does save a lot of time - balancing and checking everything manually takes me 4 hours each time and after they hit a certain level, you really need to babysit them. I'm not married and have no kids or distractions during that time.

What you set the alarms at depends on the battery type, but we can all help with that.

As for fixing problems - I disagree with the thing I read once that cells are considered "balanced" when they are all at about 2% of each other. My cells all stay within .01v of each other. If your cells stay balanced, the battery will not be an issue.

Now here is where we may disagree, but I would never use over 80-something % of the rated Ah of my pack - and I have a Cycle Analyst that tracks and shows me that. I'm pretty sure that no cell has been under 3.25v, but I'd say less than 3.0v, the alarm should go off. Everything I read says 2.80v...

As for charging, from a personal experience, I had a cell at 4.2v and it did not blow up. I read that the magic number was 4.3v.... If a cell hits over 3.70v, I shut off the charger.

The reasons for both are complex, but the Cole's Notes (c) is that the Lithium batteries are designed to operate at pretty much a constant voltage for most of their life. At the end of their use, they start the drop in voltage and the rate at which they drop increases the lower the voltage. This is different than the batteries we are used to - which lose or gain voltage constantly over time.

So mine stay at about 3.36v for 80% of the battery's life. Then they take a while to hit 3.2, then about half that to hit 3.1 and half that to go to 3.0 - theoretically. I have not had the guts to go that far yet. I might when I have the CellLogs mounted like new's setup.

So this also applies when they charge. My pack usually gets a bulk charge to about 3.55v per cell, and then I let them sit for a bit. I hook my single cell charger (get Morph's suggested B&D charger if you want to go this far) and take them to 3.70v each. Once they sit they settle at 3.65v for each cell, after a day of no use, they are at 3.60v.

Charging time can be roughly calculated if you want. Take the Ah of the pack, figure out how many you used and divide that by the A charging rate of the charger. Example - I used 15Ah, my charger is 6A, I charge for close to 2.5 hours.

Manually, this is a tough thing with lots of intuition, hence why you stick with the charger that came with the bike and use CellLog alarms.

wasp

early lithium ion batteries were dangerous and had their share of problems...how soon we forget
as for lithium polymer the new(last 2 years) is much safer