$200-300 Electric Penny Board

[EBoardBro]

I got a great deal on a penny board. ($80)

It weighs 1.9Kg or about 4.4lbs. It's deck is only 22*6 inches. I love the size and weight. I want an electric board, I've looked at Boosted, Marbel, Z-Board, E-GO, Monolith, Leif and some other company that had a carbon and bamboo series. The cheapest is $699.

I can't afford S699 and the size is greater than I'd like.

I formulated a plan to design a full E-board with these specs:

Top speed 16 MPH
Fits the Penny Chassis
Inclines of %10
Range of 5 Miles w/regenerative braking if possible
Weight, under 8lbs
And the Price goal is under $300 total, $200 to convert it, $100 for a board.

It should carry a rider of 180lbs or less.

I plan to control it in an unorthodox manner. I'm going to use a load sensor to control speed (Like Z-Board)

https://www.sparkfun.com/products/10245

$13-Shipped

It's going to use a pulley system from SDP-SI

Plastic 60T for the wheel, Metal 20T or 15T for the Motor with a 6mm belt.

$45-Shipped

I'll use a copycat Arduino Nano

$14-Shipped via Amazon

Now for the real hardware, all coming from Hobbyking.com.

MOTOR NTM 42-38 750kv 785W http://hobbyking.com/hobbyking/store/__19831__NTM_Prop_Drive_Series_42_38_750kv_785w.html
ESC AE 65A http://hobbyking.com/hobbyking/store/__24253__Turnigy_AE_65A_Brushless_ESC.html
BATTERY: 4200mAh LiFePo4 http://hobbyking.com/hobbyking/store/__14067__ZIPPY_Flightmax_4200mAh_4S2P_30C_LiFePo4_Pack.html
CHARGER Accucel 6 http://hobbyking.com/hobbyking/store/__18066__Turnigy_Accucel_6_50W_6A_Balancer_Charger_w_Accessories_US_Warehouse_.html
POWERSUPPLY 105W 15V 7A http://hobbyking.com/hobbyking/store/__20971__Hobbyking_105W_15V_7A_Switching_DC_Power_Supply.html

I can get all this shipped for about $140

I'm using an old PC case for scrap metal, bending it into a trapezoid with mesh on both ends.
I have access to electrical components and hardware, that would be very cheap anyway.

Total Cost $212 plus Board.

This is where I need help, is this plausible? I'm not looking for a hill climber, just a cruiser for flat roads. My concern is torque and battery life, they are too hard to calculate.

https://docs.google.com/spreadsheets/d/1a7Dc7tPZmHbp1irKXQaLm_iZs2tSxMDQiJkLHRK0xZU/pubhtml Here's my calculated spreadsheet, ignore the top values.

I also need to figure out how to power the Nano with UBEC, program the ESC and Nano, mount the motor for tension, manage the battery, make a regenerative circuit. I can find those answers though.

I'm new to this community, and thank you in advance to anyone willing to help.

 

[onloop]

did i read that correctly?.... you are going to mount the motor (or something else) with scrap metal from an old PC case? if so it might not be strong enough...

60T pulley? what pitch? if 5mm pitch it's too big, what is wheel diameter?

Also motor seems a bit small and also bit too high KV.

heli ESC may not have good brake function..

 

[melodious]

https://www.bubblegumboards.com

 

[torqueboards]

https://www.bubblegumboards.com

They're aren't around anymore. There website stopped working a few weeks back.

 

[onloop]

link dead, bubblegum is no longer building eboards.

 

[onloop]

haha... you beat me to it

 

[torqueboards]

lol by 60 secs

 

[melodious]

http://endless-sphere.com/forums/viewtopic.php?f=35&t=61479&hilit=Bubblegum+board

There. Happy now? :lol:

Anyways, the thread is much more useful as the information is all there so you can imitate some or all aspects of the build.

The video of it running shows how nimble & fun they can be. I'd be afraid of speed wobbles. Once you get the wobbles on that board it's hard to recover. But, it's not meant to be a straight shot ride, but rather, a carving ride.

 

[melodious]

too bad they never took off to the general public. And the for sale section is barren for a reasonable grab purchase. He probably made them to order.

 

[EBoardBro]

did i read that correctly?.... you are going to mount the motor (or something else) with scrap metal from an old PC case? if so it might not be strong enough...

60T pulley? what pitch? if 5mm pitch it's too big, what is wheel diameter?

Also motor seems a bit small and also bit too high KV.

heli ESC may not have good brake function..

Sorry, its 2mm GTG pitch. 59mm wheel diameter.

I'm not mounting the motor with scrap metal, I'm building an enclosure for the ESC, LiFePo and Nano. I'm confident it will work. I'm going to mount the motor to the truck somehow, I heard that's best.

I realize the motor is small and High Kv, that's why I compensated by using a 1:4 ratio, increasing torque 4x. I'm not trying to climb hills. I assume it's close to what the E-Go uses.

I'm open to ESC choices, but that one mentions the brake function in the specs on Hking.

Thanks for your help.

 

[torqueboards]

They could be referring to airplane/heli brakes and not car brakes.

E-Go supposedly uses a lower KV motor around 100-150kv or so from what someone has mentioned before.

That KV is ridiculously high. You won't have much luck with it. A 400-500kv would do much better. IMO You should just go with a 50mm motor. The difference shouldn't be that noticeable.

The 1:4 gearing might not be enough either.

I was using 400kv with 1:3.66 and it wasn't good enough for my tastes - even with dual motors. Torque is mediocre and braking is even worse.

Your also using 4S. I would opt for at least 6S.

 

[chuttney1]

I formulated a plan to design a full E-board with these specs:
Top speed 16 MPH
Fits the Penny Chassis
Inclines of %10
Range of 5 Miles w/regenerative braking if possible
Weight, under 8lbs
And the Price goal is under $300 total, $200 to convert it, $100 for a board.

I plan to control it in an unorthodox manner. I'm going to use a load sensor to control speed (Like Z-Board)
https://www.sparkfun.com/products/10245
$13-Shipped

Using a load sensor for control is not a bad idea until I clicked on the link and the information provided seem to tell me this sensor has a maximum load limit of 110lbs.

It's going to use a pulley system from SDP-SI
Plastic 60T for the wheel, Metal 20T or 15T for the Motor with a 6mm belt.
$45-Shipped

I would try to use all metal parts for durability. I am assuming the 6mm belt means the width of the belt which may be fine since you're limited with the amount of space on the penny board, but will break eventually as with all belts in general. A 60T gear to a 20T gear gives a 3:1 ratio. 2mm GTG pitch. I have no idea what GTG is meaning. To help you choose, make sure the overall diameter of the pulley for the wheel does not exceed the wheel itself and even then, you want as much urethane left for going the distance.

Now for the real hardware, all coming from Hobbyking.com.

MOTOR NTM 42-38 750kv 785W http://hobbyking.com/hobbyking/store/__19831__NTM_Prop_Drive_Series_42_38_750kv_785w.html
ESC AE 65A http://hobbyking.com/hobbyking/store/__24253__Turnigy_AE_65A_Brushless_ESC.html
BATTERY: 4200mAh LiFePo4 http://hobbyking.com/hobbyking/store/__14067__ZIPPY_Flightmax_4200mAh_4S2P_30C_LiFePo4_Pack.html
CHARGER Accucel 6 http://hobbyking.com/hobbyking/store/__18066__Turnigy_Accucel_6_50W_6A_Balancer_Charger_w_Accessories_US_Warehouse_.html
POWERSUPPLY 105W 15V 7A http://hobbyking.com/hobbyking/store/__20971__Hobbyking_105W_15V_7A_Switching_DC_Power_Supply.html

I can get all this shipped for about $140

Using the NTM 4238 may work, but it will overheat very easily due to a high kv value such that this motor may not have enough torque to propel you up any hills in your area, as you specified building this with a 10% grade in mind, that the speed controller may end up over heating to supply the current to keep your momentum. After reading the other comments, they are correct for why using high kv is not the right way. The motor's power may be sufficient, but 785W is equivalent to 1.07 horsepower... Not much to say about the ESC though some brands are awesome while other fail and you loose braking abilities with airplane ESC. Battery, LiFePO4 is a great battery for the discharge cure is nearly flat, you can tell when its out of juice, and takes has a higher durability, but only supplies 3.2-3.3V per cell when fully charged. Lipos beat LiFePO4 on voltage since they are 4.2V per cell at full charge and 3.7V when empty. At a 4s LiFePO4 battery voltage is a little on the low side. I would go with 6S if I can.

I'm using an old PC case for scrap metal, bending it into a trapezoid with mesh on both ends.
I have access to electrical components and hardware, that would be very cheap anyway.
Total Cost $212 plus Board.

Really think carefully. It may be thin, but will bend from the large amount of vibrations and stresses while riding if you are mounting the motor to thin pieces of steel.

This is where I need help, is this plausible? I'm not looking for a hill climber, just a cruiser for flat roads. My concern is torque and battery life, they are too hard to calculate.

https://docs.google.com/spreadsheets/d/1a7Dc7tPZmHbp1irKXQaLm_iZs2tSxMDQiJkLHRK0xZU/pubhtml Here's my calculated spreadsheet, ignore the top values.

I also need to figure out how to power the Nano with UBEC, program the ESC and Nano, mount the motor for tension, manage the battery, make a regenerative circuit. I can find those answers though.

You kind of lost me here. You set to build it in mind with a 10% grade for inclines yet just want to build it for just cruising flat roads...it will do fine for flat roads, but never for hills going up. As for making a regenerative circuit, not sure how efficient the energy you capture back will be. Have an idea how much energy you plan to get back?


Overall, not a bad start, but you want to rethink about your motor, pulleys, and battery choice. I will respect the decisions you have made. Some lessons from me... I did build my first eboard with the goal of keeping everything cheap as possible, but for use for a long time and setting my benchmark as Boosted boards 1st production board, I learned that my single NTM 5060 380kv motor with a 40 tooth spur and 18 pinion with a 70mm wheel was terrible for hill climbing and it did struggle, but fine for flat roads. I used 2 X 3S liFePO4 batteries for safety, but did not last very long. Blew past my budget, ended up spending $407.48 and from that I learn research & development is not cheap, but gotta pursue a passion for speed...

 

[EBoardBro]

Thanks for the help guys.

In response to chuttney1 and torque boards...

Choosing different motor, ESC and battery.
MOTOR NTM 50 60 270KV 2400W http://hobbyking.com/hobbyking/store/__22036__NTM_Prop_Drive_50_60_270KV_2400W.html
ESC Hking 100A http://hobbyking.com/hobbyking/store/__35679__HobbyKing_100A_ESC_4A_UBEC_USA_Warehouse_.html
BATTERY 6S2P 4500mAh http://hobbyking.com/hobbyking/store/__17823__Turnigy_4500mAh_6S2P_30C_LiFePo4_Pack_US_Warehouse_.html

That brings up cost by maybe $20, but I can still reach the under $300 goal easily.

I don't know if their's any benefit to running two 3s batteries in series but that's more wiring and money.

I going 60:28 on the gearing with this motor, because the math (Updated my original spreadsheet) gives me ~17 Mph

The load sensor supports up to 110lbs, why is that a problem? My whole body weight will never be on it. If you're thinking that's too high, I can use the Nano so that when I press 60lbs, it maxes the acceleration. I don't think that is going to be an issue.

I'll just use all metal, Done. I meant GT2(SdSPI profile) Yes 6mm width. I'm buying 3 belts, I know they'll break eventually. I have to use the 60T wheel because it clears the truck and the wheel (after boring the middle) and leaves space for the wheel. It might be too close for rocks though.

Staying with LiFePo no matter what. 6S now.

Not mounting the motor with scrap steel. I know a guy who works with metal, I'll be using something thicker for the motor. The scrap is just to build an enclosure for Battery, Esc, and the Nano.

As for hills. I'm not planning to go up any that I couldn't push myself up unpowered, so generally flat ground and 10% incline is just a number I threw out, I assume it means the slope of like a wheelchair ramp or such.

Thanks for the Help once again guys, this has gotten me hyped.

 

[EBoardBro]

As for making a regenerative circuit, not sure how efficient the energy you capture back will be. Have an idea how much energy you plan to get back?

I'm dropping this idea, it won't be worth the trouble.

 

[sami]

hi eboard have you progressed with your build at all mate?

 

[777arc]

I highly suggest starting off by building the board with a standard wireless Tx/Rx which you can get for $20 and is plug-and-play with your ESC. Once it works well, buy the load sensor and arduino, and play around with it.

 

[Hummina Shadeeba]

too bad they never took off to the general public. And the for sale section is barren for a reasonable grab purchase. He probably made them to order.

make sure you have good liability if you ever start a business!!!!
his boards were the best with his sketchup 3d printed parts. such a shame.

 

[elkick]

Absolutely true - still using it on a daily basis and it's great. I wish that he would be able to recover and continue making those boards!

 

[EBoardBro]

Here's the latest update. I'm putting this project on the back burner for now. I've been riding the Penny Board a lot lately, and the roads are terrible. I need larger wheels and a larger board. I plan to revisit this project once I'm in college. I got the whole design concept and measurements down.

I don't know if I'll stick with a penny or use a nickel or even just build my own <30" board.

If anything changes I'll be sure to give an update.

 

[sami]

thanks for the update and yeh the penny can feel a bit small on rough roads and at speed. if you post up what you have others might benefit and save you some trial and error in the future