Boosted boards reverse engineered development..

[torqueboards]

Car ESCs and Eboard ESCs Overheating
I guess, the reason why Car ESC's tend to overheat and our eboards don't is because running a Car ESC. You are literally running it at full power from the start with brakes and reversing. It's definitely a lot more strain on the ESC and motors versus on an eboard we simply go forward (no where near full power) and brake occasionally. I assume, this is why I have around 800+ miles on my eboard and it hasn't had any issues. The motor itself is not being stressed at all. Doesn't seem like there is any wear and tear on the motors either beside the cosmetic damage from being hit with rocks. This is a good thing but is also gives me a good reason that moving down in motor size would save on weight. No point in running these bigger motors while adding the extra weight.

Which means unless we are stressing the motors and escs to almost full capacity it is pretty much impossible to burn out the motors/esc. These motors are made for RC cars which are most of the time running at full capacity. We run these motors at 20-35% capacity 70-80% of the time when riding as we are simply just cruising.

Gearing Ratio and Motor Shaft Sizes
The gearing ratio isn't always flexible with smaller wheel sizes. The only problem with gearing ratio is for 76/83mm wheels we are limited to the size of the pulleys. It's much harder to achieve a 1:5 gearing ratio. From what I've noticed 14T HTD 5mm works well as there is enough threading on the pulley hub to effectively grab onto the shaft and not move. This is with an 8mm bore for the 63mm motors. I've tried a 12T and without a keyway it's better to go 14T. The 12T just didn't have enough grab on the threads. Moving down to a 42mm motor brings the shaft to 5mm. A keyway or a D shaped shaft/pulley would help in pushing that torque through than relying on the "set screws" also because the shaft is small.

With that said for example a 12T to be 1:5 would be a 60T. The max on an 83mm wheel is about 44T and on a 76mm wheel the max is a 40T Drive pulley. You can't go lower than 12T. 12T is also not even recommended a 14T would be a better choice as it would hold more teeth and more thread for the set screw to grab.

Max Gearing Ratio for 76mm wheel - The max gearing ratio on a 76mm wheel using HTD 5mm would be 12T/40T or even 38T fits better actually. That's a 1:3.3 gearing ratio. 14T/40T is 1:2.85 gearing ratio.

Max Gearing Ratio for a 83mm wheel - 12T/44T that's still only 1:3.6 gearing ratio.
90mm wheel = 12T/54T is 1:4.5 and/or 14T/54T is 1:3.85.
97mm wheel = 12T/60T is 1:5 and/or 14T/60T is 1:4.28.

That ratio isn't even including the other variables such as wheel size etc. That's just the max pulley size that would fit for those wheels. The 76mm/83mm wheels on HTD 5mm can only go up to around 1:3 to 1:3.6 gearing ratios.

Eboard ESC Braking
I agree it seems any braking above 15mph is asking to fly off my board. I definetly lean back when I try brake at higher speeds. It's better to coast it slowly. For this reason, it's safer at least for me to cruise at around 10-15mph speeds and any higher speeds I can't stop immediately which makes it very unsafe.

High Speed Eboards & Emtnboards
The higher speed eboards are not necessarily needed as much as a faster mountain board. With a mountain board the wheels are at least 8" which means we can effectively take advantage of the gearing ratios.

Belt Stripping
I'm curious to know why you are stripping all those belts. Is there not enough slack? Are the motors spinning to fast that they don't grip the teeth which strips the belts? What's actually causing the belt's teeth to come off? Have you tried using the heavy duty pulley belts from like SDP-SI.com which have fiberglass inside? My current ratio has 5 and 23 teeth in mesh.

LiPo C Rating
42 and 50mm motors at max amp run at 50-60amps. The typical 5000mah and 20C = 5ah x 20C = gives out 100 continuous amps. More than enough for a 42/50mm motor. There's no need to go 20C or more. Right?

New setup?

42mm dual motor setup 4S - I want to use a drop through deck while using 76mm wheels with a max speed of 25mph. This means on HTD 5mm my max gearing ratio would have to be 12T/40T at 1:3.3 or 14T/40T is 1:2.85. I'd prefer to use 14/40T but it changes the gearing ratio significantly. I have not done the calculations but would 1:2.85 gearing ratio work with a 4250-350kv SK3 motor? Otherwise 5055-280KV would be my second option.

Single 4S on 4250-350kv should reach 20mph? Max 53 amps.
1x - Hobby King Brushless Car ESC 100A w/ Reverse (Upgrade version) $35.99 4S 47x41x29 95g
1x - Turnigy Aerodrive SK3 - 4250-350kv Brushless Outrunner Motor $36.40 4-5S 1190watts - 53 amps 266g
1x - ZIPPY Flightmax 5000mAh 4S1P 20C $32.99 4S 143x51x33 469g 6" long
TOTAL COST = $105.38
TOTAL WEIGHT = 1.82 lbs

Dual 4S on 4250-350kv should reach 25-30mph? Max 53 amps each.
2x - Hobby King Brushless Car ESC 100A w/ Reverse (Upgrade version) $35.99 4S 47x41x29 95g 2x escs = 0.41 lbs 2x = $71.98
2x - Turnigy Aerodrive SK3 - 4250-350kv Brushless Outrunner Motor $36.40 4-5S 1190watts - 53 amps 58mm length 266g 2x motors - 1.17 lbs 2x motors = $72.80
2x - ZIPPY Flightmax 5000mAh 4S1P 20C $32.99 4S 143x51x33 469g 6" long 2x = 2.06 lbs 2x = $65.98
TOTAL COST = $210.76
TOTAL WEIGHT = 3.64 lbs

Dual 6S on 5055-280kv should reach 30-40mph? Max 60 amps each.
2x - Hobby King 150A High performance Brushless Car ESC $68.99 6S 55x60x40 150g 2x escs = 0.66 lbs 2x = $137.98
2x - Turnigy Aerodrive SK3 - 5055-280kv Brushless Outrunner Motor $49.23 6-10S 1510watts - 60 amps 59mm length 369g 2x motors - 1.62 lbs 2x motors = $98.46
2x - Turnigy 5000mAh 6S 25C Long Lipo Pack $52.99 6S 299x55x26 820g 12" long 2x = 3.6lbs 2x = $105.98
TOTAL COST = $342.42
TOTAL WEIGHT = 5.88 lbs

Those setups above I think work out pretty well. Let's say the board/trucks is about 7lbs. It comes out to 10-16lbs give or take. That 16lb board dual 6S w/ 50mm motors is going to be a pretty powerful. I would think is pretty much exact to what BoostedBoards is running. 5000mah gives me about 8-15 miles.

Rider weight?
I'm about a total of maybe 200 lbs on my board with my backpack on. Do you think someone who is 230-240 lbs it would make a difference? I would think it would be harder to get a single 4S setup to 20mph for them.

 

[benj]

Fantastic work guys, thanks for sharing all this info with us.

 

[made_in_the_alps_legacy]

Single 4S on 4250-350kv should reach 20mph? Max 53 amps.
1x - Hobby King Brushless Car ESC 100A w/ Reverse (Upgrade version) $35.99 4S 47x41x29 95g
1x - Turnigy Aerodrive SK3 - 4250-350kv Brushless Outrunner Motor $36.40 4-5S 1190watts - 53 amps 266g
1x - ZIPPY Flightmax 5000mAh 4S1P 20C $32.99 4S 143x51x33 469g 6" long
TOTAL COST = $105.38
TOTAL WEIGHT = 1.82 lbs

Thanks a lot torqueboard, I hope we see low cost setup like this one above validated soon :wink: (I fully agree about a too conservative tendency of our built)

 

[torqueboards]

Thanks a lot torqueboard, I hope we see low cost setup like this one above validated soon :wink: (I fully agree about a too conservative tendency of our built)

Someone please test it out . I'd like to test it out but I already have about a total of 3 or 4 boards. I'll get rid of a few and test it out soon. I'm currently only running a Dual 6S which would be like 3S on each motor. A dual 4S would be faster. I'm also going to try out GT2 3mm pitch and 9mm width as I can't find the 15mm ones. Most likely a 16T/60T on 5055 motors since they are already 6mm and 4250's are 5mm motor shaft.

BBMan.com actually has GT2 3mm pitch in 15mm widths. I might see if I can fit room for 15mm width belts.

 

[666yeti666]

LiPo C Rating
42 and 50mm motors at max amp run at 50-60amps. The typical 5000mah and 20C = 5ah x 20C = gives out 100 continuous amps. More than enough for a 42/50mm motor. There's no need to go 20C or more. Right?

I would like to comment on this.
The C rating of a lipo is a normative for holding the proper voltage under load and as such has a direct relation to the internal resistance. Internal resistance is something we do not want, since this will cause heat and reduce the pack voltage under load conditions.
The higher the C rating, the lower the internal resistance and the higher the packvoltage under load is, and vice versa.
So far so good.

The problem is that C rating is something that is not standardized by any of the (limited!) battery manufacturers, eg. When a 6s 5000mAh pack has a C rating of 20C it would imply that this pack can deliver 20x 5Ah = 100A continuously. But at WHAT OUTPUT VOLTAGE ??? In other words ; this does not say anything. You can only , MAYBE use it as an INDICATION only to select a battery from the SAME manufacturer (comparing different battery brands only by c rating is really useless, many tests have proven this).
I even suspect that the difference between different C ratings is determined in the factory by a selection procedure, just by trial and error.

My own experiences with lipo batteries is that I use them for more then 10 years already in my electric cars, planes and helicopters and can tell you that C rating is only a loose marketing term to increase the price ….

For my own reference I read regularly the tests of a German guy; Gerd Giese, which is very knowledgable and does a lot of battery testing with very good equipment. As you can see on his page is that there are remarkable difference between lipo brands and also many “C rating promises” cannot even be delivered in practice : http://www.elektromodellflug.de/index.html (check “akkutest” and press at the bottom of the page ‘googl translate’)

So I want to say : check practical experiences from others and “buy with common sense” …..

Regards
Sebastien

 

[beto_pty]

It died...
little motor died.. was able to get over 100 km on it.. it did not actually burn out.. it shorted out as two of the cables got peeled off at the juntion and a big puff of smoke followed... no worries though.. had only 1 more pulley left.. all the previous ones stripped..

Moving on to bigger motors and powers, however the limiting factor of this proyect was NOT the tiny ESC or the tiny motor... it was the 5mm shaft, that made it imposible to use a larger tooth than the 3mm gt2... so there... lots of fun..

Reagrding Lipos...
The fastest ive ever drained my twin 6S 2650 mah battery (5300 mah total) is 22 minutes... that gives me roughly 3c draining speeds... this makes me think that anything above say 5s is overkill in our case.. a 20s battery would theoretically allow me to use it up in 3 minutes...7 times faster than I can do this... maybe for people using 10S lipos the numbers change, or for dual motor setups running at 40 mph.. but for 6S folk running single motors, or people doing under 25mph i dont think there are any worries here. My suggestion.. spend your hard earned cash in better bearings (maybe ceramics) and better helmets LOL

 

[torqueboards]

42mm or 50mm SK3 should last you forever. What motor do you plan on using? That's the main reason why I don't like the 42mm motors as well as they are 5mm shafts. The 50mm motors are 6mm shaft which max is also 16T.

Are you referring to a single motor when draining at 3C?

 

[beto_pty]

I agree on the sk3 point we are as a whole probably building overdesigned boards..
My max lipo use is at full throttle using my 6264 tacon bigfoot at 6S is under 3c...hence no real worries with 20c batteries so far. Maybe using double motors you can go through them faster... but again you would have to be humming at over like 90 mph to drain 5000 mah batteries in such a short time.. the other aternative would be to have 1000 mah batteries or something dinky like that...

 

[torqueboards]

I agree on the sk3 point we are as a whole probably building overdesigned boards..
My max lipo use is at full throttle using my 6264 tacon bigfoot at 6S is under 3c...hence no real worries with 20c batteries so far. Maybe using double motors you can go through them faster... but again you would have to be humming at over like 90 mph to drain 5000 mah batteries in such a short time.. the other aternative would be to have 1000 mah batteries or something dinky like that...

Do you think there is a big difference w/ the torque output on the 5mm shafts versus a bigger shaft? I would assume it is more stable on a bigger shaft.

Do you suggest using 4S over 6S? 6S works fine for me and has enough output - uphill it's not as fast as a 10S but still not slow either. I can't really throttle it as the hills I climb up are full of potholes and uneven pavements. I like using the 6S but there's something about 8S/10S that makes me want to use it. Maybe, I just like to overdo it. I should just stick to 6S. I think I'm going up hills at about 10mph. I don't have enough space to go up faster yet at least.

Boosted boards I read their blog post again they are using 12S with 2800mah which is why they go up hills at about 20mph. They use (12) 18650 or similar type batteries 4x3. 2800mah is estimated at 6 miles so my estimate of 5000mah fully used is about 8-15 miles is pretty accurate. I usually get about 6-8 miles and swap my batteries when they go around 3.5v or 3.7v this is also with uphill downhill immediate acceleration and braking. Only because, I don't want to swap batteries in a more inconvenient area. I tend to like to swap batteries where I can place my board at arm level - instead of swapping while on the floor.

Do you plan on re-creating your build or working on an upgraded version? I'm waiting on some new motor mounts but I want dual 5055-280kv SK3 motors on 6S. Should be very lightweight.

 

[beto_pty]

Motors tend to like to run at around their highest design voltage... so a motor that is designed to run 4s-12s will be happier at around the 11-12s range than it will be at the 4-5s range since it will be drawing less amps per unit of power (Im assuming honest specs on motors not blown up numbers to sell more)... hence I like to run at 6s vs 4s... at whatever watts I go... (200 lb rider+ 15 lb armour and helmet+ road friction + board electronics weight+ incline+ wind) it will be drawing less amps. Im sure the ESC appreciates this lower amp load as well..

I have an irresponsability problem... I am not responsible and grown up (at 43) enough to have 12s power at my fingertips and not use it... I have 2 6s batteries that I could hook up in series to obtain 12s, I have a 12 HV ESC (no brake on this however) and my 6264 talon will supposedly withstand 14s... and I have a new sprocket in the mail that will allow me to go 45-47 kph..so if I were so inclined I would probably have a skateboard that would go 90+kmph ( briefly while I fell off and died...) and then who would send you crappy videos of remote control binds and setups LOL.
I have hence decided to have a mental max of 6s, and have negotiated with myself upping my current 16:48 ratio to 19:48 (ratio as this still uses my 6s setup) and maxes my speed at about 45-47 km/hr. There are no significant hills where I skate and Id rather have the extra 5% speed as opposed to unused torque... If I were to break this mental limit it would only be to overgear an 8s setup for use on hills or maybe for offroad use... no plans for that quite just yet however...

Regarding the shaft size just the mechanics and parts available to fix a sprocket to a 5mm shaft are much more complex.. My 8 mm shaft not only feels more reliable .. it also allows me to use larger screws.. and to flatten out a good segment of the shaft to insure no slip..( and i still overkillit with a gallon of loctite LOL) 8mm is for me the ideal balance between thin enough to be managable and thick enough to be workable... The 5mm shaft s probably mechanically strong enough but it sort of just doesnt seem so... so ill stick to 8mm from now on...

ON a totally different topic how is your plastic gear for the abec wheel coming along? actually I will PM you on this so I dont auto-Hijack this thread..

 

[torqueboards]

Do you think those 42mm motors that are rated 5S should be good with a 6S setup? Only problem is they have 5mm motor shafts.

I definetly like the (2) 6S Long Lipo's that are about 26mm in height on HK. I want to get two of those and connect them in a series for 12S. However, can we use the 5055 or 6354 SK3 motors that are rated 10S with a 12S setup? It seems the only motors rated for 12S are the SK3 6374 motors.

The plastic gear is actually great. I probably have maybe 80 or 100 miles on it and it's working fine. The ABEC 11 hub adapter I use is working great too. It's a lot better than my first with just an inside retainer. The idea of a hub centric design was definetly a lot smarter. Thanks to voodoojar's suggestion.

 

[beto_pty]

I plan on using the 5060 motors only on an 8s setup max, probably more frequently on a 6s. My 6264 tacon will theoretically handle up to 14s, but my HV esc will "only" (only between quotes) handle 12s http://www.hobbyking.com/hobbyking/store__38787__The_Turnigy_Sentilon_V4_HV_100A_OPTO_5_12s_Bulletproof_Speed_Controller_w_RPM_Sensor.html
it is awesome and sports unreal power, tried it at 10s very very briefly.. but without a brake it is literally suicide to ride for someone with my skating abilities (or more accurately.. lack of) the dynamic break is programed to be either off... or at 100% power when not accelerating... so it is pretty much imposible to use with the brake... it should do nicely however for a future build making an all terrain scooter or such...

These 6s are cheap and fit nicely under my board... http://www.hobbyking.com/hobbyking/store/__9181__Turnigy_2650mAh_6S_20C_Lipo_Pack.html I get 6-8 km per pack of these depending on how agressive i ride.. 100% flat out about 5 km per pack. Remember there are no hills where i live so this DOES not apply to san fran. They balance nicely and are small enough that I will purchase 2 more packs and have a large 4 pack for full 20 km flat out autonomy... or 30 or so km of fooling around...

Glad to hear about your printed hub, soes it include the gear or does the gear have to be purchased separately and then screwed on top of it?

 

[torqueboards]

The battery you recommend is 141 x 41 x 31mm. Checkout the Zippy Flightmax 5000mah 3S 20c which is my personal fav as the price is amazingly cheap per 1000ah. Dimensions are 145x52x25mm. Not that much different from yours and actually a lot thinner. They are also only about $20 a piece. http://www.hobbyking.com/hobbyking/store/__8579__zippy_flightmax_5000mah_3s1p_20c.html

I just sell it complete for the hub. Works well though. You can always use voodoo's 3d model and buy a pulley and drill through it too.

 

[beto_pty]

Cool battery suggestion that is also an option...

Why have you not printed the gear on? Acording to the info out there while it might bot be good enough for the motor sprocket they suggest it is good enough for the wheel

 

[torqueboards]

Oh, I get what your saying. I didn't print the gear on as I don't trust the ABS pulley. The pulley from SDP-SI.com is a harder polycarbonate that won't break at all. The pulleys from SDP-SI.com work real well too though.

 

[beto_pty]

I agree. They work very well..I guess I was looking for a one-shot alternative. Lol

 

[joanfork]

Wow great post man!
Very useful information, It's fantastic to know that motors with this power will actually work. We will have to figure out how 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.