esaj

Electric Unicycle Specs sheet

62 posts in this topic

another similar project (maybe not maintained though): 

http://socialcompare.com/fr/comparison/monoroues-electriques-sbu-self-balancing-unicycles-2km82kah

A Google docs spreadsheet would be a useful tool for this case. I could provide a plain one if necessary, though I believe one needs a Google account to edit it. 

Thanks for this (I think I've seen it sometime, but then forgotten about it) :)  That should give me a start on other manufacturers/models (plus there's lots more information here in the forums too, once I get around to actually pick it through). I was thinking about Google Docs, but not sure if I want to use my personal account for that... 

I've been hogging on so much projects lately, that I better soon stop taking up any new ones, as they've become pretty time consuming  :D

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This is a great idea.  Maybe you can add a column for introduction year?  This way we could keep it sorted by the most recent few years and not have a million Ninebot, Airwheel, IPS, etc. entries cluttering things up.

Once we get it finished, maybe we can have it hosted in the downloads section of the forum, with a permalink at the top of the General Forum.

And @esaj if you've got too much hit me up and I can help with this.  I like this sort of thing.

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And @esaj if you've got too much hit me up and I can help with this.  I like this sort of thing.

Here's the ODS (OpenOffice/Libreoffice) -file I've used, feel free to continue, I probably won't have the time at least for some days to do anything about this:

 wheel-specs.ods

Most of the data is from the forums & manufacturer/reseller sites, so I'm not 100% it's correct ;)

 

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Awesome @esaj! I wonder if we should look at creating a special Wiki (or become part of a larger Wiki) where we can add information about EUC's. For example, a introduction page, a page about about buying a EUC, the above spec sheet, a page about BMS shutoff etc. The good part would be that everyone can edit a Wiki so they do not go stale, and the burden can be shared among many enthusiasts B)  Anyone here knows an easy way to get an eWheel Wiki going?   (and we should call it eWheel so we can become inclusive with regard to electric skate boards and other electric things with wheels :D)

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Cool -- didn't know about this. However, the advertisements are really annoying and big.... and the pages need quite a bit of work. I guess without advertisements we need to pay up B)

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@esaj,

I update your form with kingsong spec.

Thank you, I'll try to update the first post later today, now I must go balancing on top of an A-ladder with a paint bucket and a brush ;)  In the mean time, if anyone else wants to update the sheet, please use the version in high'tems' post, so I won't have to deal with multiple files, thanks

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esaj,

Thanks for all your work - the table is very useful - you are a regular dynamo - Australia appears to have other brands  - AirCruiser; and  "PUKKA X7 MONwheel";

A no brand which states - "

To prevent injuries caused by speed, Air-Fly-Wheel comes with a speed control design. When speed exceeds 10km/h, the front part of the treadle will rise slowly; 

when the speed exceeds 16km/h, the treadle will rise to a 10° angle, to prevent you from inclining forward to further accelerate. As the speed decreases, the angle of the treadle will also lower itself. 

Rider will be fully protected

  1. Wheel will deactive when exceed 45 degrees
  2. Speed limit at 10km/h wheel will prevent further acceleration
  3. Low battery protection will turn on when battery less then a10%

Is this full "BMS" protection for the rider; or just nice words? - I have tried to follow the raging debate in this forum's "electric-unicycles-bms-problem-and-solution"

Alan

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esaj,

Thanks for all your work - the table is very useful - you are a regular dynamo

No problem, but don't trust it blindly, it would still have to be at least double-checked for any errors... ;)

Australia appears to have other brands  - AirCruiser; and  "PUKKA X7 MONwheel";

A no brand which states - "

AirCruiser and the nameless one sound like generics, I don't know if Pukka's are any better.

To prevent injuries caused by speed, Air-Fly-Wheel comes with a speed control design. When speed exceeds 10km/h, the front part of the treadle will rise slowly; 

when the speed exceeds 16km/h, the treadle will rise to a 10° angle, to prevent you from inclining forward to further accelerate. As the speed decreases, the angle of the treadle will also lower itself. 

Rider will be fully protected

  1. Wheel will deactive when exceed 45 degrees
  2. Speed limit at 10km/h wheel will prevent further acceleration
  3. Low battery protection will turn on when battery less then a10%

Is this full "BMS" protection for the rider; or just nice words? - I have tried to follow the raging debate in this forum's "electric-unicycles-bms-problem-and-solution"

Alan

These sound like the typical wheel protections that are on most wheels.

1. means that the motor will lose power if the wheel is tilted 45 degrees (at least sideways, never tested tilting back or front, but might be in those directions too). The idea is probably that the wheel shuts down if it falls to its side.

2. refers to tilt-back, the tilt-back will start at 10km/h and gradually increase with speed, until it reaches the maximum tilt at 16km/h.

3. will probably mean that the wheel goes to full tilt-back regardless of speed, once the battery has less than 10% capacity left (so it activates when the battery voltage drops under a certain value).

None of these are BMS-related, the battery pack BMS can still cut the power at any time with too low voltage or too high current.

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According to http://forum.electricunicycle.org/topic/372-what-do-we-know-about-king-song/?page=2#comment-9290 the KingSong 14C does not have a swappable battery. According to the same thread http://forum.electricunicycle.org/topic/372-what-do-we-know-about-king-song/?page=2#comment-9249 the 14C has the 800W option, so 14B and 14C might be interchanged in the table. I believe the reason could be that the 800W option is not available with small battery. If the battery were swappable, it would be harder to prevent the small size battery from being used with the large motor. 

Edited by Niko
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I read in one spec that around 500 charge cycles was what can be expected from the battery [life] - so if you use the wheel every other day - expect about 3 years life? If batteries are generally not swappable [per Niko above? or is this in relation to between models?] - I presume replacing batteries is possible!

NiCd batteries used to be 'rejuvenated' [not infinitely] by shorting the poles then re charging - is this possible with Lithium?

What is the general opinion with trainer wheels - good or bad - I rode further with the trainers but not sure I learnt to balance any better!!??

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I read in one spec that around 500 charge cycles was what can be expected from the battery [life] - so if you use the wheel every other day - expect about 3 years life? If batteries are generally not swappable [per Niko above? or is this in relation to between models?] - I presume replacing batteries is possible!

The 500 cycles that the manufacturers state seems pretty conservative for high quality cells... The original batteries on my Firewheel F260 have been ridden something like >400 cycles, and they still charge to a bit over the nominal capacity (268.3Wh the last I checked), but Firewheel never lets you discharge them to below 3.5V per-cell resting voltage. Something like Gotways let you discharge them to around 3.0-3.1V before telling you to stop, so the batteries will wear quicker if you always ride them to empty.

It also depends on the usage and storing, the deeper (lower voltage) and faster (higher current) you discharge them, and the faster you charge them (high current charging with speed-charger), the less cycles they can handle before capacity starts to drop. If you store them for a longer period, keep them in a cool place and never fully charge them, yet never let the per-cell voltage drop below 2.5V (for others than LiFePo4 and Li-titanate), so they need to be checked and recharged a bit from time to time, as they slowly discharge by themselves too. If the cells have been below 1.5V for over a week, do not try to charge them (it is said that small short circuits start to form inside the cell, and it can catch fire if charged). The optimal charge for storing is between 40-80% (also for usage this would be optimal, it's said it around triples the cycle-lifetime of the battery, but of course then you'd get less range from the batteries). 

Battery university is a good source to read more about Li-Ions (and batteries in general), for example:

http://batteryuniversity.com/learn/article/types_of_lithium_ion

http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

http://batteryuniversity.com/learn/article/bu_808b_what_causes_li_ion_to_die

Sometimes the numbers are a bit wrong (for example, if you compare to more "modern" chemistries of high quality cells, that contain some proprietary additives that prolong the lifetime of the battery, also the discharge C-ratings are higher for the cells that have been made within the last few years).

NiCd batteries used to be 'rejuvenated' [not infinitely] by shorting the poles then re charging - is this possible with Lithium?

No, once the capacity of a Li-Ion starts to fade, there's no magic tricks to bring it back, different thing if it has "fallen asleep" due to low power and the possible internal protection circuit has turned off, there are special chargers that can try to revive them, but I don't think wheels use the cells with internal circuits anyway, as they're more expensive, and the BMS already handles the protections. Shorting lithium-cells is a very bad idea, the cell will likely catch fire (if there's no BMS or internal circuit in cell with short-circuit protection or the BMS has been shunted) and possibly explode.

What is the general opinion with trainer wheels - good or bad - I rode further with the trainers but not sure I learnt to balance any better!!??

I stopped using them after less than half an hour (maybe 10 minutes in garage with them, and then another 10-15 outside). While they did let me get a little hang of how the wheel behaves, I found them to be more of a nuisance in learning. But for others, they might be useful for a longer period, guess it depends on the person.

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Thanks for all the info once again.

Batteries; where can they be sourced ?  Are they easily replaced by a handyman? Do they look like a typical 'D' Cell?

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Thanks for all the info once again.

Batteries; where can they be sourced ?  Are they easily replaced by a handyman? Do they look like a typical 'D' Cell?

Some wheel-resellers sell replacement battery-packs (at least I've seen some in some French shops), and some even custom high capacity-packs (at least one German shop). Cells are also readily available, so building the packs yourself is also an option, but requires at least soldering, and maybe spot-welding machine (if you'd have to for "tab" the cells yourself), you'll also need a BMS (A Battery Management System, circuit board that takes care of controlling charging, balancing and discharging) for that big pack (typically 16 cells in series, some wheels have less). I went with asking a company that sells cells whether they build custom packs, and they directed me to a guy who builds large packs (up to 2500Wh) for scuba diving gear, like diving lamps and underwater "scooters". 

Most wheels use standard Li-Ion 18650-cells (the name of the format refers to the size: roughly 18mm * 65mm, but the size varies a bit, usually less than 1mm):

BatteryComparison1.JPG

It depends on the wheel how many packs you can put in it (ie. how many fit), so that and your wallet limit the maximum capacity (usually the bigger the capacity per pack, the more expensive, at least if it's made with high quality cells). In principle they're easy to replace, once you have the new pack(s), but that depends on the wheel, with most wheels that have larger mainboard- and battery compartments that are accessible from the outside, I'd expect everything to be fairly easy (once you have the packs and the connectors match etc.) , not so with Firewheel...  ;)  You can read about my so-far-not-that-lucky Firewheel battery-project here: http://forum.electricunicycle.org/topic/605-firewheel-custom-battery-pack/ 

At least it looks like the "big manufacturers" (Ninebot, Kingsong, IPS, Inmotion, Solowheel, Firewheel, probably Gotway?) use cells from high quality manufacturers (Samsung, LG, Panasonic...), can't say for sure about the rest. 

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Thanks again esaj, interesting you say I'd also need the BMS to replace the battery pack - won't the existing one work?  Is the soldering to connect to the battery ends? won't the heat damage the battery? If this is correct, I'm surprised the wheels don't have battery cradles !?

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Thanks again esaj, interesting you say I'd also need the BMS to replace the battery pack - won't the existing one work?  Is the soldering to connect to the battery ends? won't the heat damage the battery? If this is correct, I'm surprised the wheels don't have battery cradles !?

I meant you need a BMS to build a custom pack... the ready-made packs of course have their own BMSs already, so pretty much all you need to do is connect them to the mainboard (and maybe solder some connectors on them, if they don't come with the right kind). And yes, you could probably use an existing BMS (assuming it works). Don't know about cradles, as the battery packs get a lot of physical shocks during use on wheels, I guess the welding is the best approach so they don't come off as easily, and don't take too much space, as it's always limited. Maybe they could work though. Typically it looks like the tabs are welded to cells, and the cells are welded/soldered together and shrink-wrapped tightly along with the BMS.

Spot-welding is usually used at least for connecting the tabs to cells, but they could be soldered too (don't know how well they'll hold). It seems most stores have at least some cells available already tabbed (typically Z- and/or U-tabs, in Z, the tabs point to opposite sides of the cells, in U-tabs, both point to same side of the cell), or you can ask them to tab the cells like you want (depending on the store, if they have the machines, and it probably costs extra), but some people have built their own machines. As the cells are heat sensitive, the spot-welding has to be done fast, without heating the cell too much, the "professionals" use spot-welding machines made specifically for battery welding:

Professional-Power-Li-ion-Battery-Weldin

The tabs are then used to connect the batteries together in series (either by soldering or spot-welding), or in case of some BMSs, soldered or welded directly to the BMS:

F4R7D2MG1XBDXKS.LARGE.jpg

The cells in above image are not Li-Ion, but the idea is the same: connect them in series using the tabs.

HTB1j.ZfGVXXXXc1XFXXq6xXFXXXi.jpg?size=1

The above is the kind of BMS with which the cells are connected directly to the BMS with the tabs, no need for separate balancing wires.

(Sorry for the huge images, I just picked up something fast from Google image-search ;))

Also the BMS balancing wires need to be soldered/otherwise connected between the cells:

16Slogo-1.jpg~original

Hope that clears a bit how the batteries are built, I just ordered my custom packs ready-made, as I don't have spot-welding equipment or even a proper soldering iron for that kind of work  ;)  And had I ordered the cells & BMSs myself, the parts alone would have cost about as much as the parts + work done by a professional, who could get the parts cheaper, plus now they've got warranty for any defects.

Edited by esaj
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Very comprehensive - thanks very much

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Rockwheel GR 16 the maximum speed is 35kmh. You can fix it to the list because there is now 30+.

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Rockwheel GR 16 the maximum speed is 35kmh. You can fix it to the list because there is now 30+.

Done, thanks :)

Hi easj, just found this uniwheel on eBay with a comprehensive spec sheet

Do you have any comments?

Typical generic. ;)  Probably good for learning if you can get it cheap, unless it's very low quality.

 

 

Edited by esaj
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esaj, Looking at a 'Dragonman' unicycle quoted battery as a 36v 2.2 Ah battery which Google tells me is + 79.2 Wh but the Chinese supplier says is a 132 Wh!!

http://dragonmen.en.alibaba.com/product/60137843838-800450046/Dragonmen_Hotwheel_self_balancing_unicycle_single_wheel_electric_scooter.html

As a first wheel and at $A350 its quite cheap!! Would would you say?

 

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