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Battery Explosion?

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Chances are if you have researched electric unicycles you have probably read through the details of the SoloWheel.  Claiming that they use high quality parts including battery.  That buying other brands would be putting your safety at risk due to battery explosions and fires.  However the price of the SoloWheel has put you off and doubt has been cast in your mind about buying a different brand.

 

As there are lots of members here and assuming the large percentage of us own an electric unicycle.  Has anyone here actually experience a battery explosion / fire from their electric unicycle or know someone who has?

 

Before I owned an electric unicycle I searched for a long time regarding the battery issue and only found one very dubious article about it which I dismissed pretty quickly.  Even YouTube one of the best places for true reality videos from members of the public didn't have any videos addressing this.

 

 

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As far as I know, only eucs that use LiPo (Lithium Polymer Ion) have experienced fires WHILE charging.  I have not personally witnessed nor heard of any forum or group members having that happened to them personally.  Only heard stories of them through Michael Chacon (Solowheel company guy).  I think most all eucs now are using Li-Ion (Lithium Ion), specifically 18650 packs and I don't think there's a single reported case of fire from that in the euc community.  That said, Solowheel uses LiFePo4 (Lithium Iron Phosphate) cells and it is the safest by far.  The drawback is lower energy density.

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You have illustrated my point exactly Arbee.  A company man promoting his own wares while using fear to demote the competition seems like a slim ball move to me.

 

I'm all for leveling the playing field so I hope someone who has had doubt placed into their head while reading such articles will have more piece of mind while deciding on a future purchase of any brand from reading this thread.

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I have a Tg-F3 and it says "lithium" battery. Doesn't say LiOn or LiPO. Wondering if you guys know anything about it. Anyone else has a Tg? The charger that came with it doesn't look like a "balancing" charger. It just has one LED light that turns green when charged. 

Edited by PlanetPapi

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Balancing can also be packaged with batteries. It does not necessarily have to be in the charger.
Several vendors indicate that it would be LiPo batteries. But really have 18650 cells.

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Here's a video of a single 18650 Li-ion battery shorting out then exploding. I use the same batteries (almost the same but still 18650) for my vaper but the flat top versions. 

 

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Here's a video of a single 18650 Li-ion battery shorting out then exploding. I use the same batteries (almost the same but still 18650) for my vaper but the flat top versions. 

 

What do you like us to say?

....The title of this video is:

Controlled" explosion of a UltraFire 18650 battery

 

I can take some carbid I have at home and some water....there no much more I need for a "controlled" explosion

(do not try this if you not know what are you doing or you can seriosly be injured or killed)

But usually you use carbid in a save way like in carbid lamp in mines.

So as long your battery is not overcharged (this should be controlled by a BMS) there is "no" danger.

I have a 16'000wh Lithium-ion battery under my seat and others 100'000 EV too, still no problem what I know.

The Chevrolet Volt exploded years ago was not turned off right as it should (after crash test), Teslas problems and some mysterious news (also in the past) I know was the battery not defect!

"

However, it was actually caused by the driver hitting a large piece of metal debris, which damaged the battery part of the car - and was not due to a fault.

The Model S has previously been touted as the safest car in America and it received among the highest scores ever recorded from the National Highway Traffic Safety Administration (NHTSA) in August.

"

If I worry about something driving the EU, then that the Controller Board fail and I have to learn fly or get injured!

If this is happen in a curve (during my slalom I like) I will have no chance at all and just slip and fall faster then I can act in any way.

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Keep in mind that every cell phone anymore is using li-ion batteries. So are tablets, laptops, etc. Yes lithium ion batteries can explode. But how often do you hear of it happening? One in a million batteries? Fewer? The biggest problem with lithium ion batteries is they short out if they completely discharge.

For those not aware, lithium ion batteries, that are completely discharged, then stored for long periods of time until they dissipate completely, will short internally. This ruins the battery. So just store lithium batteries with a full charge

Edited by StridAst

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It only blew after all the 'cooling liquid' stop coming out....just add more cooling liquid, problem solved....lololol... 

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@tum13n Heh... You do know that the YouTube video you just linked is posted from this forum right?

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I think it was so that the video device were cells that had been wrapped in paper. So really primitive, and I do not think anyone longer be produced. So forget the video.

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I saw a MSuper weeks ago with a battery shortage/ fire. Regarding the owner it happened while driving. One of his kids was the driver but nothing happened to the kid. I can post a picture later.

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@tum13n Heh... You do know that the YouTube video you just linked is posted from this forum right?

naturly not.
I have not yet explored all the forum.

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From what I have seen of the firing battery, I would say the problem is caused by a short circuit which makes the battery hotter and hotter, till cooling (?) liquid is out and the upper part blows out like a bear cap. So, wrapping it in a thicker enveloppe just prevents heat to dissipate and so increases the problem, or shortens the necessary time for the bat to explode !

It just makes battery more resistant to wounds or knocks, which a wheel battery is not much subject to. The main precaution seems to prevent shortages because it is difficult to install a fuse on each battery element !

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8 minutes ago, Wheel Rider said:

Does anyone know what caused this http://youtu.be/i9FQ to happen and what's the brand of the EU?

i9FQXJ60f7I

That video has been discussed here. It's very old prototype apparently.

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Does anybody know if "ni-mh" batteries are effective for unicycles ?

Edited by Lovely

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13 minutes ago, Lovely said:

Does anybody know if "ni-mh" batteries are effective for unicycles ?

Probably not, but could be wrong... while (according to Wikipedia) the energy density of nickel-metal hydride can approach that of lithium-ion batteries, this still leaves the problem with voltage. NiMH has a pretty low nominal voltage of 1.2 volts, while li-ion cells usually have around 3.6-volt nominal voltage. So you would need three times the amount of cells to get the same voltage as with a 16S (16 cells in series) lithium-ion battery, whic is what most wheels use. 48-cell battery would be pretty huge, you probably couldn't fit it inside the wheel (depending on model), unless you'd make three separate 16-cell (with about similar sized cells as 18650 li-ions) and wire them all in series inside the wheel (you need a wheel that has space for at least three normal 16S-packs). I don't know how good or bad NiMH handles high discharge rates, or how fast the voltage drops with discharge, but I'm not saying it's impossible either...

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11 hours ago, esaj said:

Probably not, but could be wrong... while (according to Wikipedia) the energy density of nickel-metal hydride can approach that of lithium-ion batteries, this still leaves the problem with voltage. NiMH has a pretty low nominal voltage of 1.2 volts, while li-ion cells usually have around 3.6-volt nominal voltage. So you would need three times the amount of cells to get the same voltage as with a 16S (16 cells in series) lithium-ion battery, whic is what most wheels use. 48-cell battery would be pretty huge, you probably couldn't fit it inside the wheel (depending on model), unless you'd make three separate 16-cell (with about similar sized cells as 18650 li-ions) and wire them all in series inside the wheel (you need a wheel that has space for at least three normal 16S-packs). I don't know how good or bad NiMH handles high discharge rates, or how fast the voltage drops with discharge, but I'm not saying it's impossible either...

 

11 hours ago, esaj said:

Probably not, but could be wrong... while (according to Wikipedia) the energy density of nickel-metal hydride can approach that of lithium-ion batteries, this still leaves the problem with voltage. NiMH has a pretty low nominal voltage of 1.2 volts, while li-ion cells usually have around 3.6-volt nominal voltage. So you would need three times the amount of cells to get the same voltage as with a 16S (16 cells in series) lithium-ion battery, whic is what most wheels use. 48-cell battery would be pretty huge, you probably couldn't fit it inside the wheel (depending on model), unless you'd make three separate 16-cell (with about similar sized cells as 18650 li-ions) and wire them all in series inside the wheel (you need a wheel that has space for at least three normal 16S-packs). I don't know how good or bad NiMH handles high discharge rates, or how fast the voltage drops with discharge, but I'm not saying it's impossible either...

Thank you for your reply esaj ! I was looking for cheap alternative regarding battery, for my pinwheel, to take it to the airplane, as the original battery hit the limits 190wh! What about these 9v NI-MH batteries? I could take even more mAh. version and they are not that expensive and probably not that dangerous as well..? They are quite small.. Say, if I take 7 pcs. 9v batteries and instal them as a parallel? Is 63v acceptable for 350w motor? Sorry about my bad knowledge of electronic and english..

SN150064.JPG

Edited by Lovely

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22 minutes ago, Lovely said:

 

Thank you for your reply esaj ! I was looking for cheap alternative regarding battery, for my pinwheel, to take it to the airplane, as the original battery hit the limits 190wh! What about these 9v NI-MH batteries? I could take even more mAh. version and they are not that expensive and probably not that dangerous as well..? They are quite small.. Say, if I take 7 pcs. 9v batteries and instal them as a parallel? Is 63v acceptable for 350w motor? Sorry about my bad knowledge of electronic and english..

SN150064.JPG

Like at least most (if not all) battery types, NiMH are at a higher than their nominal voltage when fully charged:

"A fully charged cell supplies an average 1.25 V/cell during discharge, declining to about 1.0–1.1 V/cell (further discharge may cause permanent damage in the case of multi-cell packs, due to polarity reversal). Under a light load (0.5 ampere), the starting voltage of a freshly charged AA NiMH cell in good condition is about 1.4 volts."

As 9V isn't divisible by 1.2V, it's probably 8 * 1.2V cells in that one, so the nominal voltage is probably actually 9.6V and fully charged it could be 11.2V (if that 1.4V per cell fully charged is right). At 11.2V per battery fully charged, placing 6 of those in series you get 67.2V, which coincidentally is the same voltage as typical fully charged li-ion. At 9.6V nominal you get 57.6V, again pretty much what nominal voltages for most li-ion chemistries are (with 16S, the typical nominal voltage is between 57.6V and 59.2V). So it sounds like on the voltage-side it should be just fine for the wheels (as long as those nominal voltages I quoted above for NiMH hold). Even if it's not exactly those values, it should be close enough (but I could be wrong, so it could also be too much if the voltages are higher... ;)).

300mAh (0.3Ah) would only give about 17.3Wh per series (0.3Ah * 57.6V) , so you would need a lot of those 6-battery series in parallel (or use ones with much higher mAh rating) to get "enough" watthours. The motor will pull large currents during start up (getting going from standstill), accelerations and climbing, so they should also be able to dish out fairly large currents, but I have no idea on the discharge rates of NiMHs... I'd place a lot of those 6-battery series in parallel so the current per series should be low, something like 10-20 paralleled series just to be on the safe side, but that's going to take a lot of space and probably 60 or 120 pieces of those 9V batteries is going to start to cost a lot ;). Most likely the cheap ones won't be good enough (GTL is listed as a "bad brand" here:  http://michaelbluejay.com/batteries/nimh-brands.html ). 

Also they'd probably be a pain in the ass to charge, as I'm not sure if you can use a li-ion charger for those, or if they need to be charged separately... 

 

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So thats why good lion batteries are so expensive... Thank you very much for this useful information esaj! I should think about that!

Edited by Lovely

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Has anyone looked into armouring the EUC batteries? E bikes usually house them in aluminium containers. I was thinking fabric may be possible as well, some sort of bag made out of nomex and kevlar.

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Bikes have no place to put them, so they install a container and aluminium seems a good choice, solid, shock resistant and esthetically correct.:)

But I think that no case will bear a Li-Ion fire which produces a large amount of heat and gazes often called "explosion" which usually communicates to other battery element. In fact, when it burns, the STEEL box of the element is not solid enough:wacko: !

What is more, a bag or box will lower the cooling of batteries which is the main danger and cause for the burn.:(

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