Boosted boards reverse engineered development..

[beto_pty]

So just like a billion other people I saw the boosted boards ted conference and thought an electric skateboard was the coolest thing ever. Throughout the conference boosted made it sound like the electric skateboard was their inventions.. i have never seen one... so I never even thought to look up a forum where people build Super-UBER-boosted boards...

So I looked up boosted with my credit card in hand ready to pay the 1450 or so in cost plus dhl priority shipping to panama... and couldnt buy one...pissed off i decided to build one myself... I have a cnc i built from buildyourcnc.com a while back (awesome toy by the way) which i converted to milling aluminum... i have loads of experience with gears, welding, some electronics, thermoforming and assemblies... have a semi complete workshop at my disposal...what could ever possibly go wrong...

Back to my tale of ignorance...So I looked up outrunners up and found out they were little itsy bitsy motors... figured out i neded to get me a,suitable ESC whatever that was.... later found out it was an electric speed controller... batteries.. oh man.. thought as soon as a lipo touched my hand it would explode.. and burn up my car.. that they all failed the first day, and got all bloated inmediatelly.. and charging them was not only a dark science but also extremely dangerous and expolosive..... stumbled upon Hobbyking and realized i could buy all this in one place and a gun permit was not required to buy batteries, right then I decided this might actually be something that could be done.

I had never longboarded/skateboarded so I again had no idea what I was doing. A guy was selling his "slighly used" board on a local website ( I live in the Repubic of Panama), and had been doing so for like a year.. so he was asking 40 bucks (down from 100) or best offer for it, so I got that for cheap and I purchased it had good trucks and 98mm abec11s on it (talk about luck) the wood was destroyed.. so no wonder he was having a hard time selling it. II decided to be unique so I set up to mill my own skateboard.. the only aluminum board on the planet... a funky 38"x10" 1/4" thick with 1/2" support longboard.. (only to later realize that someone had beaten me to this...by like 5 years!!)




Bookmarked boosted webpage, read everything 10 times over and reverse engineered the whole thing..given the known wheel diameters/width the diameter/width of the motors was sort of possible to guesstimate, so I spent a couple days figuring out what could go with what... and just ordered what sounded appropiate..
Here is my reverse engineered sheet LOL...



"Huge" powered 4038 motors LOL they were 750 KW each... actually 750 Kv and had nothing to do with KW... they were 26 bucks each...
http://www.hobbyking.com/hobbyking/store/__30864__NTM_Prop_Drive_Series_42_38_750kv_785w_USA_warehouse_.html
Then a huge ESC.. man Im talking 60 amps!... again a pair for a cheap $30 bucks each...
Batteries were the awesome 5000 mah 4s for 26 bucks...
http://www.hobbyking.com/hobbyking/store/__18631__Turnigy_5000mAh_4S1P_14_8v_20C_hardcase_pack_USA_Warehouse_.html
Charger was 9 bucks... and I had an old laptop power supply that worked fine...
http://www.hobbyking.com/hobbyking/store/__36906__Hobbyking_DC_4S_Balance_Charger_Cell_Checker_30w_2s_4s_USA_Warehouse_.html
Figured Id have a 5:1 ratio gearing on the motor to wheels, as well as a 3:1 in case the 5:1 was overkill.. (100 tooth wheel gear, 20 and 32 tooth motor gears)
got those from sdi gt2 2mm ones that i have used before (although not for anything this tough) they were around $60 for the two systems.
The remote was the cheap $19 gt-2 i believe...
When I received the hobbyking box i was surprised..the 2 motors and the 2 escs fit in the palm of my hand...this could not be good... also didnt realize the esc came without bullets... the batteries with 4mm, the motor with 3.5mm, and the battery charger with alligator clips... so i had to send away for all of these.. overnighted them and a bit over a week later they were here.. (yeah overnight is 7-10 days in my world)

Welded bullets, connected escs to receivers to motors... thought both motors were damaged.. I grabed them by the body and tried to turn the sprocket and they would not turn... laughed at my ignorance when i realized (what I assume) is the reason for their name... awesome! Connected batteries and heard a battery count and tarara...

Started milling the motor mounts and working out the kinks... I cut wooden parts initially to test for fit as my machine cuts wood literally 10 or 20 times faster than aluminum, I also have tons of left over hdo from other proyects so making changes is quick cheap and painless...3 or 4 iterations into the design I had a wooden piece that I mounted and spun the wheel...man it was fast.. here is the link (remember the support is wooden just to verify measurements)

https://www.dropbox.com/s/l0r8lbxuofbz6el/20140106_133034.mp4

Didnt want to make double mounts till I figured out if the design was sound.. so I threw a 44 lb bag of raw material on it and checked it to see if it would roll.. it did.. threw another one..88 lbs and it accelerated away..nothing blew up.. no magic smoke, no explosion from the lipos...

https://www.dropbox.com/s/r6x5tmplvkprhdn/20140107_163720.mp4

Might have stopped there.. the design called for 2 motors (i weigh 190 lbs so the experiment was a clear sign that two motors would be able to pull me along) however I figured at less than 30 bucks for the motor and the esc i could afford to see which burned up first... the motor or the esc... so I jumped on it... andit pulled an cut out..pulled and cut out.. over and over.. figured i was over amping the esc or the motor and this was the motor's protection system turning on and off the current to save itself.. along came no shortage of problems, ... motor gear was loose... tightened it with larger set screws, stripped the belt, retightened the motor.. it ran on and off.. not so much fun.. but not dispointed in any way either

https://www.dropbox.com/s/9z1h8mdrq9dhnpr/20140107_163919.mp4

That night I found this website and reordered all the "correct parts"...150 amps esc, 6364 etc, differnt stuff from sdi etc... so I knew I was looking at minumum 15 days before the stuff got here......figured the on/off behavior was just my incorrect choice of parts and decided to turn my mini-motor board into a board for my kids.. the oldest girl weighs 44 lbs so this was a perfect fit (yeah nice responsible dad right.)..

I continued working on it while my stuff got here and by chance realized that my remote control antena was disconnected..it had come loose when i took apart the huge hobbyking remote in an effort to shrink it down...i reexamined my esc-minimotor system and reread the instructions.. if overamped the motor turns itself off.. and has to be manually reset, however if the remote looses signal it turns itself off.. if it regains signal it turns on again. this was not an esc amp problem it was a transmission one... I reset all the connections..and tried again... Magic... my single motor aluminum skateboard made with all the incorrect parts at half the cost of a "real" one was pulling me along at 20.3 mph on flats acording to gprride... I rode it for about 10 minutes till I stripped the belt.. one of the screws had come loose, i checked the voltage and it was warm.. not hot just warm and the esc was room temperature.

View attachment 2

I did the math 750kv (rpm) x 3.7 (volts) x 4 (# of bateries) x .307 (wheel perimeter) x (1/5) (gearing ratio) x 60 (minutes/hour) gave me a theoretical speed of 41 km/ hour (25 mph)!! subtract all my inefficiencies/errors/misalignments and Endomondo`s calculations sounds correct! I was so Happy... a single motor! a single tiny motor doing this..so I got to work on the second mount inmediately..
Today my new parts arrived however I have refused to open the box up untill Im done with this mini challenge...

It is awesome it purrs.. it hums.. is has power ... rode it today and maxed at 24.2 mph...with a 4s battery voltage of 16.1

https://www.dropbox.com/s/0ax7ld050qppuma/20140127_145223.mp4

happy as a clam...
Will work on some enclosures and such... just amazed at the power of those tiny motors...

 

[torqueboards]

Awesome work! I dont know about an aluminum board theres no flex in it. Hows the 4s? I've been wanting to try a 4s setup. Crazy thing is that supposedly boosted is running those 42mm motors on 12s.

 

[beto_pty]

I want to be super respectful in my answer.. I admire boosted boards for their awesome work..
That been said...I no longer believe they use 12s..there is no reason to.....this is not a conflict generator comment.. just the product of having stumbled upon something I did not expect... I will ride them some more..see if they blow up or fry...

 

[torqueboards]

Hrmm.. Makes me want to try out 4S. I started off at 10S and was more power than I needed for my area. I dropped down to 6S. Does the 4S pull you up hills with 200lbs.

Boosted mentions that they use 12S on their blog. It looks like most manufactured eboards are all 36v meaning 10s+.

You are now using 63mm motors and the 150 amp escs?

I'm working on a dual 50mm motor build on 6S. I'd like to try the 42mm on 4S as well though. Perhaps run a 4WD longboard on 50mm's or 42mm's.

 

[Justinian]

Wow great write up man.

It's fantastic to know that motors with 750kv will actually work, you'd just need to gear it down a lot.

I'd imagine you'd have to kick start it though? let us know how the motors and esc hold up cause at 4s, you'd be drawing a lot of current.

best of luck!

 

[lpbug]

Nice build. I like the way this is written. One thing though- I'm interested in starting an aluminum deck myself, any chance you can post more pictures of the deck? How is the 1/4 in holding up for you?

 

[beto_pty]

By the way are the videos and dropbox files visible?

The Aluminum started as a half inch 38x10 inch slab... made a jig so that it could be removed and replaced for several iterations to figure out a sweetspot...First drilled like 50 holes in it to verify it all worked out.. then timidly milled about an eighth.. it flexed a bit.. then milled another eight.. leaving double beams in the center of original one half inch thickness, actually might have overdone it a bit, or the milling table was not perfect as the rear has 3/16 thickness.. it is not particularly heavy and it has some flex to it... i'll try to get a video of me on it.. later today. However 1/4 inch without beams will be too thin.. Ill post more pics and send you the cutting file for mach3 if you want..youll definitly have to tweak it to suit you but it might save you some time..
View attachment 3




Torque
yes im running 6s on a bigfoot 6364.. at 55 bucks it was a steal (got 2 free shipping)... with a 6s hobbywing. However I ordered a Turnigy Sentilon V4 HV 100A OPTO 5-12s http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=38787 which i saw in this thread
http://endless-sphere.com/forums/viewtopic.php?f=35&t=56254 where geckoch mentioned it came stock in his zippy scooter connected to a 6364... that went 60kpm... Figured if it was good enough for Zappy it was good enough for me.. I also ordered 2 5000mah 5s batteries to try the setup on 10s.. probably not for regular use..just to be able to say my skateboard is faster than your lada.. (LOL third world joke)
Unless you are planning on racing dual 4s should allow you to hit 30 mph on flats using 1:4 reduction...no idea on hills...
Concerning the 10s boosted design.. I in my infinite knowledge (eyes turn to the horizon)...might think that the esc turns that into 2 x 6s separate currents where they run rewound lower kv motors at 6s and less than 500Kv... that is what I would do...here is an example it can be done at just about 30 bucks (Jade or distributer price category) http://www.hobbyking.com/hobbyking/store/__19610__NTM_Prop_Drive_Series_42_58_500kv_1300w.html
Regarding hills... we dont really have any around where i live.. if they are they will be rolling as opposed to steep... I will try to ride over some soon. Right now the main drawback is physical.. the tiny gt2 20 tooth gear strips away the belt if im not ever so careful with the remote.. or if it looses signal for even a second when i pull on it.. and none of the other belts allow me to gear up 5:1 while fitting a 5mm shaft while the big gear being less than 3.5 inches while being a 9 or 15mm belt... I need all 4 to work for the part to fit and be reliable... i bought 10 belts so i should be able to last at least till i burn either a motor or an esc..LOL
If I can get my belt to stop slipping/stripping I will start riding single motor/single esc till I burn one or the other, just to see where the boundary lies..

 

[got92]

Man, this is fantastic .

Maybe your esc is a bit too small. Your motor made at max 55A and if the motor get overamp (can go a motor overamp? XD), maybe after a start.

I want to be super respectful in my answer.. I admire boosted boards for their awesome work..
That been said...I no longer believe they use 12s..there is no reason to.....this is not a conflict generator comment.. just the product of having stumbled upon something I did not expect... I will ride them some more..see if they blow up or fry...

I think the boasted board use an higher voltage to have a smaller battery. To have the same Watt with a lower capacity you need a heavier battery.

 

[beto_pty]

Rode for over an hour yesterday.. everything smooth.. electronics holding up well so far...

https://www.dropbox.com/s/uw0j7obgj5n0hp5/VID-20140128-WA0004.mp4

This setup will have problems working reliably...not due to the wimpy ESC or the minuscule motors.. it is destined to fail due to the 5:1 ratio required and the 5 mm shaft on the 4238`s... due to the 20 tooth mini gt2 gear required Belt stripping is just a recurring issue.. no matter how careful one is with the trigger... a larger "tooth" will impede the 5:1 ratio required.. a larger final gear wont fit and this setup just wont cut it.. I have 8 more belts and will go through them in the next 12 maybe 16 rides... and then will be out of belts.. Im already tightning the belts WAY over "Correct" torque and might actually damage the front bearings before I run out of belts LOL... So tonight, after a restless week boosted may again sleep soundly... not because of their enviable Tesla Engineer designed ESC/ Uber amped high voltage 10s power supply/ dream upon a dream regen braking, but because of their rewound motors offering a lower KV that bypasses the nonexistence of a 15mm gt2 20 tooth belt with a 5 mm bore..LOL...

If I were to try again (an knowing me I just might) I'd try This combo
http://www.hobbyking.com/hobbyking/store/__22036__NTM_Prop_Drive_50_60_270KV_2400W.html (think torque is doing this) using the 6s lipos and a 2.5:1 gearing ratio with that solid 8mm bore.. should rock and provide over 25mph max speed and pretty good pull... However acording to basically all the comments the magnets fall off.. so that might be iffy as well...
and go with twin http://www.hobbyking.com/hobbyking/store/__14500__Hobbyking_SS_Series_190_200A_ESC.html ESCs at 30 bucks and the comments on them are superb! albeit without brakes
Theoretically a single esc/motor 6s setup should be under 70 bucks in motor/esc combo and should be able to power you at over 20mph if you gear it to 1:3.3...as well as use all the battery/clamps/cable setup from another serious build ...but I ramble and digress...

I will start riding single motor my 4238s as of tomorrow and see who burns up first the motor or the esc.. just to give this thread a blazing end..
the I'll move to the 10s Sentilion Bulletproof ESC Build... http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=38787 with a single tacon bigfoot and 10s batteries running on 3:1 gearing...

 

[torqueboards]

Haha.. that sucks to hear.. Why don't you try these SK3 4250mm motors at 350kv. A lot less than KV than the one you are using now - http://www.hobbyking.com/hobbyking/store/__18170__turnigy_aerodrive_sk3_4250_350kv_brushless_outrunner_motor.html $34.44.

Since they can buy in volume. They have complete custom EPM motors, gears and drives. Why don't you just try it with the GT2 5mm pitch 15mm width belts, pulleys? 5mm seems to work fine. Adding it to 15mm would be better for durability and reliability issues. Actually, 9mm seems to work great although I would definitely like to try the 15mm's.

 

[beto_pty]

Edited the previous comment torque..take a look at it..

I agree on the belting issue... that limitation just came out of nowhere.. was worried about electricity and power where I knew noting... not belts and gears where Im supposedly an expert lol.. Reality check.

I like the motor you suggest.. just have grown to dislike 5mm shafts.. everything is made for 8mm... including if one were so inclined #25 chains and gears,,

 

[torqueboards]

Those NTM 50mm's with an 8mm shaft is nice. However, from what I've seen/heard on the forum the NTM motors aren't as good/reliable as the SK3 motors. I've been running my SK3 motors and they work real well. I have over 800+ miles on 6374mm's.

I currently have (2) Sk3 5055 280kv motors which I will most likely put on a dual rear wheel mount and run on 6S. Just waiting on the motor mounts and to weld them on the trucks. Should make the board a lot lighter than the 63mm's. I think it's only like 1/2 lb I'm saving anyways LOL. I wish those (2) 4250 motors were at least 6mm pulleys. 5mm is smaller than the standard size 6mm. I may not go that route unless I end up figuring that out.

SK3 4250 350kv = 266g
SK3 5055 280kv = 369g

103g difference x 2 = 206g = .45 lbs difference. Might not be worth the difference.

SK3 5055 280kv is 369g = .51 lb difference from SK3 6354 215kv motors is 485g.

NTM 5060 270kv = Wouldn't fit on a dual rear wheel mount unless some modifications. 454g in weight.

Better off with a SK3 6354 215kv 485g motor compared to the NTM 5060 270kv 454g same weight size already.

IMO for reliability issues. Might as well use what works well. It's already been tested what's $40-$80 more for better quality. No ESCs & motors burning out saves you money in the long run.

Single motor setup
For ESC = Flier ESC > Ez Run Pro 150A $89 > HK 150A $67.20 / Trackstar 150A $72.45 - About $80/each
For Motor = 5055 280kv > 6354 215kv > 6374 190kv - About $60/each

Good luck on your build. You'll enjoy it! Keep us updated it's always fun to see the other builds out there. Cool thing - I just realized everyday on my commute to work I save about 30-45 minutes sometimes an hour a day commuting because I ride my eboard to work after bart/train.

 

[beto_pty]

Put in about 45 minutes on the single motor, just long loops on a vacant street about 1/2 a mile per loop.. (800 meters) had to stop since I stripped the belts..LOL...the motor got hot but I dont think burning hot... saved by the bel..t?
Interestingly the esc was cool as a cucumber...so I guess the motor is probably going to give up before the esc..
No worries though milled my cnc motor holder for the new 15mm belts and pulleys that came in the mail today on the bigfoot ... so ill probably be mounting that on monday or so.. unless I burn the minimotor before that in which case Ill post some pics of the dead motor and move on..
Awesome experience this build.. these tiny motors (if available in half the kv) would perfectly suited to a lightweight skateboard...

 

[torqueboards]

Why don't you give the 4250-350kv one a try? http://www.hobbyking.com/hobbyking/store/__18170__Turnigy_Aerodrive_SK3_4250_350kv_Brushless_Outrunner_Motor.html. There's also a 5045-450kv http://www.hobbyking.com/hobbyking/store/__18173__Turnigy_Aerodrive_SK3_5045_450kv_Brushless_Outrunner_Motor.html. If you plan on fitting (2) on a rear wheel.

Which 15mm belts did you use?

 

[kkEdlund]

Why don't you give the 4250-350kv one a try? http://www.hobbyking.com/hobbyking/store/__18170__Turnigy_Aerodrive_SK3_4250_350kv_Brushless_Outrunner_Motor.html. There's also a 5045-450kv http://www.hobbyking.com/hobbyking/store/__18173__Turnigy_Aerodrive_SK3_5045_450kv_Brushless_Outrunner_Motor.html. If you plan on fitting (2) on a rear wheel.

Which 15mm belts did you use?

Agreed. The 5045 and 4250 both look very promising. I think I will be trying the 4250 personally.

 

[torqueboards]

Why don't you give the 4250-350kv one a try? http://www.hobbyking.com/hobbyking/store/__18170__Turnigy_Aerodrive_SK3_4250_350kv_Brushless_Outrunner_Motor.html. There's also a 5045-450kv http://www.hobbyking.com/hobbyking/store/__18173__Turnigy_Aerodrive_SK3_5045_450kv_Brushless_Outrunner_Motor.html. If you plan on fitting (2) on a rear wheel.

Which 15mm belts did you use?

Agreed. The 5045 and 4250 both look very promising. I think I will be trying the 4250 personally.

That 4240 might be a better deal as the 4250 length wise is actually 58mm's so don't buy it . The 4240 is actually 50mm in length.The 5045-450kv is 49mm in length. I think the difference between the 4240 and 5045 for two motors is close to .5 lbs in weight.

 

[beto_pty]

Update on the single minimotor setup.. another belt through the grinder and the motors hot (though not burning to the touch, could hold my hand on them)... however went through just about the whole battery down to 12.3v on a 4s battery.. motor was hot, the esc cool and the belts stripped... Seems these tiny motors and esc can actually handle the load, and with half the KV your suggested ones could be geared up to 1:4 (resulting in a lower top speed of 15mph) but good torque and probably no overheating problems for a super economical build...

Torque
Here is a video of my 15mm belts... These wont slip even under the most demanding situations... they can also be mounted fairly loose so as not to provide stress to the motor bearing as well as compensate for any misalignment between the parts..
https://www.dropbox.com/s/okrn9u2pd2v38x2/20140202_113844.mp4
I received notification that my 2 Quanum Pistol Grip remotes will be available tomorrow so I will try it out and see if I can get it to work... have been waiting over a month for them, would really hate it if they are duds...

 

[torqueboards]

Beto - Please do tell me if you get those working. I have 2 as well that are sitting as I was not able to get the Rx/Tx to pair up.

 

[666yeti666]

Beto - Please do tell me if you get those working. I have 2 as well that are sitting as I was not able to get the Rx/Tx to pair up.

I'm also very curious. I wanted to order one, since it is so compact, light using 1s lipo and is without any unnecessary extra's ...

regards
sebastien

 

[got92]

Update on the single minimotor setup.. another belt through the grinder and the motors hot (though not burning to the touch, could hold my hand on them)... however went through just about the whole battery down to 12.3v on a 4s battery.. motor was hot, the esc cool and the belts stripped... Seems these tiny motors and esc can actually handle the load, and with half the KV your suggested ones could be geared up to 1:4 (resulting in a lower top speed of 15mph) but good torque and probably no overheating problems for a super economical build...

how many km have you done? It's a good news that the esc can handle the load

 

[beto_pty]

Sorry torque was unable to go to the post office today.. will do so tomorrow and if possible will update as soon as i get out of work...
Are you able to see the videos and stuff.. Ive been to lazy to open a youtube account but will do so if the videos/files/[pics cannot be seen...

According to Endomondo I have over 18 miles on them... assuming I use it roughly half the time id say anywhere between 30 and 40 miles... The cables look ok so far.. no evidence of burning or such.... interesting how one's perspective on something changes when one goes from trying stuff to see if it might work and when one is actually trying to break it...Id be delighted if i ran out of belts and was unable to

Got92 I believe the escs are ok for this duty.. they do not get warm at all... in fact the last couple times i did not even comment on them as I felt they are definitly not the weak link here... Im actually starting to think neither are the motors LOL..

 

[dirkdiggler]

So you are using a 60a HK car ESC on 4s? I really think someone needs to post the highest amps they have seen on a wattmeter. I doubt it is ever more than around 50amps. Everyone is wasting money on buying big car ESC's.

 

[got92]

According to Endomondo I have over 18 miles on them... assuming I use it roughly half the time id say anywhere between 30 and 40 miles

Range with a single charge? Or i haven't understand or this is fantastic

 

[torqueboards]

So you are using a 60a HK car ESC on 4s? I really think someone needs to post the highest amps they have seen on a wattmeter. I doubt it is ever more than around 50amps. Everyone is wasting money on buying big car ESC's.

That's exactly what I've been thinking lately. There's also no point in using 63mm motors as well since we never give it the true voltage. It's better as it's not being over utilized but it's also not needed. A 63mm motor is capable of a 12S battery to itself.

Especially for the dual escs/motors.

For example - 6S and (2) Motors - A (2) 3S 5000mah setup in series for 6S controlling 2 motors would only output half of the power/amps to each motor, if even. Basically, 3S to each motor not 6S. Meaning that there isn't much difference between a single motor 6S versus a dual motor 6S besides the fact that the power is distributed to two motors versus one. Power wise it's pretty much the same. Riding wise it is better because the power is distributed over two motors. Better stopping power as the power is distributed by two motors. Less stress on one particular motor.

To effectively, get the benefit of the two motors and reach the necessary wattage/amps. You would need a single 6S battery on each motor to reach the max wattage.

So actually having a Dual 6S on 2x motors is actually 6S power being divided to run 2x motors. Your amps would be half for each motor as the full voltage isn't there. You would need to have 12S in total and/or 6S to each motor. With that being said? Does this mean that we can run a 12S batteries on (2) 6S 150Amp ESCs? Or would it be better to have 6S batteries to each motor/esc. How would it be different if we had let's say a FlierESC/AlienESC that is 120Amps 8S ESC? Could we run 12S together to be divided to (2) motors at 6S ESC each?

Another example is HumboltRC's 4wd mountain board build which is (4) 50mm motors and (4) HK 150Amp ESCs w/ (4) 6S Batteries that reaches 40-50mph. This works because he has a 6S 25.2V to each motor directly. This is much more powerful than a 12S ESC, 12S LiPo w/ (2) 63mm motors. I would say it's about half as slow. The setup above is much more current and power flowing to each motor directly.

THIS would mean it's not TRUE. - 10S ESC w/ Dual 63mm Motors is not 3kw each for a 6KW setup. It would actually be around 3KW if not less. meaning the same (2) 50mm's with (2) 6S batteries directly to it would equal 3KW as well.

In reality, we don't ever need to even use 10S/12S as the ESC's are pretty much double in price. The price for an HK 150Amp ESC or EZ Run Pro 150Amp and a 6S Battery to each motor would make it the same and much cheaper.

IMO - The best setup would be (2) 50mm SK3 Motors w/ (2) 6S Batteries and (2) EZ Run Pro 150A ESCs. Then we can pull the full 60-65amps and 1500watts from each motor. The only issue is that the 6S LiPo's are huge and would affect the size of the enclosure. I prefer a 1-1.5" at most for underneath the deck. Question is - How fast would this setup end up going? I would imagine this board would reach 30-40mph? What do you think?

Is this correct? What do you guys think?

On off switch?
Also to throw it out there - What do you think is the best way to have an on/off switch to turn our systems on/off? Are we able to use a simple LED Rocker switch? http://www.ebay.com/itm/4pcs-Red-Yellow-Green-Blue-Dot-Led-12V-16A-Car-Boat-Truck-Rocker-OFF-ON-Switch-/321310105651?pt=LH_DefaultDomain_0&hash=item4acf932033. I would assume if we mount this switch through the ground wire. There isn't as much current in the ground wire and it could possibly work. Using a 150Amp/300Amp Circuit Breaker is overkill and bulky?

 

[beto_pty]

Got92 I misunderstood your question.. I can get 5 maybe 6 miles (the belts die before my battery does)of a 5000 mha 4s battery.. I have currrently traveled roughly 35 miles on the motors so far without them burning up, not exactly around the world but probably better than many would have thought possible on a single motor. I do again remind you there are no hills here, so any of you reading this that live in the alps or the grand canyon better turn somewhere else...

Dirk Actually I ran my 6264 motor on this same esc (4S) and it did not even get warm..
https://www.dropbox.com/s/46880k66tppzil1/20140130_153906.mp4
rode for 3.8 miles according to endomondo and max speed of 18.5mph... I was actually testing the 15mm belt setup and had to stop when the motor pulley got loose.

Torque..
Yes and No and maybe...
1. The final speed is a function of the gearing ratio applied... A single 4038 750Kv motor on a 4s at 1:5 ratio will pull me (192 lbs) at 18.3mph on flats... if my 90 lb niece was riding my skateboard i could probably get her going 38-40 mph with a 4s battery. I'd change the gearing ratio from my current 5:1 to 3:1, use the 0.30 m perimeter on my 98mm wheels, leave everything else the same (4 x 3.7 x 750 /3 x.3x efficiency) on flats.. on a double motor system with double 4s batteries could probably do 70-80mph as I could probably gear the motors 1.5:1.. on a quad system... she would break the sound barrier LOL...my point is that the gearing is a flexible variable and we can play around with it, there is no set max for a 4s..
2. The acceleration breaking available is a function of our ability to stay on the board... (unless strapped on) there is a set number of g`s we can withstand before falling off our board.. so infinite possible motor acceleration/breaking does not translate directly... having the capacity of going from 0 to 60mph in a second does not mean we can stay on the board at this speed.. My skateboarding skills are probably under par... but I cannot accelerate full throttle on my 6 s setup with my esc set to anything even remotely close to full esc acceleration, also breaking at 75% power in an automatic fall of my board...
3. People like to have a board "that can do 40mph" how often (if at all ) they achieve or have achieved that speed is a diifferent thing altogether... Im looking for a 40Kph max speed on my board so I can cruise around at 30 kph without stressing that im burning us my setup... I doubt I will be able to go maxed out at 40 kph for any lenght of time...
SOOOOOO... if we were planning on a double motor system on 5s using the 350 Kv motor that went 25 mph with a 200 lbs load and 4s batteries the question would only be how many motors and what gearing one would use. I bellieve this is no news to anyone.. however wiith the 5mm shaft we might end up back in belt stripping territory... the 9mm wide 3mm HTD belt is the largest alternative available with a 17 tooth sprocket and 40 tooth wheel gear.. we get 7 teeth pulling.....dont know if I like that... ive never ACTUALLY seen a 9mm wide 3mm HTD belt so i might be mistaken... maybe it is strong enough and Im stressing about nothing?
https://www.dropbox.com/s/1ydl4lm2il0ztkt/ScreenHunter_04%20Feb.%2004%2020.18.jpg

Im not sure the 6s single battery vs double 6 s battery theory necessarily holds.. I believe we delve into the c rating more than the amount of batteries... ie a 40c battery will probably provide as much as 2 20c.. also I doubt we are pulling the max c rating on our batteries... I say this cause mine dont heat up the least bit... so lets say maybe we require 5c per esc for our setups and as long as we attach less than 5 esc we stay under the 20c rating? interesting question though...

Maybe an interesting setup (keep in mind the gearing as that is my biggest problem with the current 4238 setup) would be the 60 amp escs connected to the 50mmsk3 using 4s and geared for 25mph? at 14.8 volts? I see you already have the 50mm sk3 so there is no changing that.. however the 60 amp escs might be an interesting choice as opposed to the 150.. and at 25mph 4s should do the trick... how will you deal with the 6mm shaft?

Regarding the switch.. have no idea.. would assume current to be the same everywhere in the circuit...hopefully im wrong and one can place a small switch instead of the mamoth standard one.