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Higher capacity battery tech


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That would be nice, doubling the capacity... I've done some research into batteries, but can't claim to know that much of them (or really undestand the chemistry/chemical reactions). This site has been fairly good for all kinds of information:  http://batteryuniversity.com/



There are many types of lithium-ion -chemistries used, but to consumers, they're usually all advertised as "Li-Ion". From what I've gathered, Solowheels use LiFePo4, at least Ninebot uses LiNiMnCoO2 (it's shown in one of their videos: https://youtu.be/5nN674pundw?t=2m1s "Ultra capacitor lithium battery  The third generation Ion polymer battery of Nickel, Cobalt, Manganese and Lithium"), and Firewheel uses Sony US18650 V3 -cells, so they also seem to be LiNiMnCoO2. Guess it could be the usual type for most EUCs, though the chemistry seems to usually have rather low discharge C-rating, but don't know if it's different for the cells used in the wheels. Lithium-titanate would look nice in specs (safe, high discharge C-ratings), but has low energy density, and don't know if such batteries are available. Also they'd need to use more cells to reach the around 60V voltage, as the nominal voltage seems to be lower than in other chemistries. Probably pretty expensive too. Lithium Nickel Cobalt Aluminum Oxide seems to have high energy density (Wh/kg), and is used by Tesla(?), but is also the most unsafe one..? Probably high cost too.

There are probably more exotic chemistries than these, at least a company called Tadiran Batteries (http://www.tadiran.com/) produces something like Lithium-Thionyl-Chloride batteries, which seem otherwise good, but don't have high discharge rates (but that could be maybe circumvented by using more parallel packs?):

Lithium thionyl chloride 3.6 V cells have the highest energy density and voltage of all commercial lithium types, with a service life of up to 15 to 25 years. These cells are ideal for applications requiring very low continuous-current and/or moderate pulse-currents.

There's something called "PulsesPlus" version of the chemistry, which can give temporary high discharge currents, but I don't know enough to say if this would work with wheels or not. The temperature range under which the chemistry can be used seems also larger than normal chemistries (-45 ... +85 Celsius for Lithium thionyl chloride, most common chemistries seem to have a range around 0...+60 Celsius) and "Extended temperature"-version which can work between -55...+125 Celsius.

They also have an apparently undisclosed chemistry "Lithium-Metal-Oxide" for normal and military uses ("TLM Military Grade"). Although they seem at least safe (I saw a video somewhere where they drill through a charged cell to prove it doesn't explode or catch fire Edit: couldn't find the video anymore, so better strike-out this claim, but at least the site claims that "The batteries have performed well in a variety of safety tests, including nail penetration, crush tests, high temperature chambers, short circuit and charge tests... TLM Military Grade batteries comply with MIL-STD 810G specs for vibration, shock, temperature shock, salt fog, altitude, acceleration (50,000 gn) and spinning (30,000 rpm) as well as UN 1642 and IEC 60086 standards for crush, impact, nail penetration, heat, over-charge and short circuit, and can be shipped as non-hazardous goods."), while the maximum discharge current seems high, the capacities of single cells seem pretty low (but that's probably because the form factor is smaller than 18650?), and you probably can't find ready-made battery packs anywhere, so would need to buy the cells and do the battery pack yourself or find someone who can do it for you. Don't expect them to be cheap either ;)

There are probably other manufacturers with more exotic chemistries, and ongoing research for new chemisries, so hopefully we'll see somewhat higher energy densities soon(ish). It appears that most chemistries have their tradeoffs between energy density (Wh/kg), power density (max discharge), safety, cost etc. Probably the current chemistries used have been chosen due being "suitable" for the kind of use wheel motors do and due to costs...

From the technologies of future, the most promising ones seem to be supercapacitors and Lithium-Air -batteries. IBM has done extensive research on Lithium-Air, but they still estimate the commercialization of the technology to be 5-15 years away. There are also other companies that are studying Lithium-Air, so we can just hope that the breakthrough comes earlier. From what I've understood, there's no separate oxide-metal used in Li-Air, but the battery literally uses the surrounding ambient air. LiAir has a theoretical maximum energy density of over 11000Wh/kg, but that's a theoretical number, whereas current chemistries have theoretical values somewhere between 200-400Wh/kg (if I remember correctly, didn't look them up right now), but limited in reality somewhere between <100-300Wh/kg(if you look at the graph in batteryuniversity page).


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Esa, I am so glad your big fat brain is working on this.

To me, the worst thing about this technology right now is the weight of the unit. I know batteries aren't the bulk of the weight, but every little bit counts.

Like, I'd love to have a 10 pound 12" wheel that only goes 5 to 10 miles. It would be a wonderful tool in the city.

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Esa, I am so glad your big fat brain is working on this.

To me, the worst thing about this technology right now is the weight of the unit. I know batteries aren't the bulk of the weight, but every little bit counts.

Like, I'd love to have a 10 pound 12" wheel that only goes 5 to 10 miles. It would be a wonderful tool in the city.

I think that even the 12" models, like Fastwheel EVA pictured below, weigh in around 15-17 pounds (7-8kg) even without batteries... They would need to use lighter materials for the motor/tire to go below that, and then durability might become an issue. Maybe some new nanomaterials can change this in the future. EVA looks nice though, but I've heard that the pedals are too low and hit the ground easily, otherwise could be a pretty handy transport in cities, available in 260Wh (9kg = around 19.85 pounds) and 312Wh (9.5kg = 21 pounds) models.



Edit: Some specs:

Maximum Speed22 km / h
Range22 - 25 km28 - 32 km
Maximum weight120 kg
Power (maximum peak)350W (1000W)
Maximum slope18
lithium battery170 Ah cells Samsung260 Ah cells Samsung
Operating systemFastwheel OS 1.0
Operating Temperature-10 To 40 ° C
Charging voltageAC 220V 60Hz ~ 50
Charging time90 minutes120 minutes
Dimensions334 cm x 474 cm x 165 cm
Weight with battery9.0 kg9.5 kg
Wheel SizeΦ304.8 mm (12 inches)
Distance pedal to the ground102 mm
Screen16 mm * 16 mm
Optional Accessoriestraining wheels and strap

It does say 102mm (10cm) distance from pedal to ground, which sounds pretty standard to me... I don't remember whether it was John Eucist or Kevin Lee who had tried it once, but they also said that the tire had been a bit flat, which might have affected the pedal hitting the ground easily too...

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