Electric mountain board

[Mattchoooooooo]

I have been picking up bit and bobs of information from the site for some time now so thought I should finally get around to posting my build. Some years ago I made an electric skate board and a mountain board both with brushed motors, with the lead acid batteries they where so heavy I never really used them that much. After seeing the RC powered Lipo boards on-line I thought I should upgrade.

I made an unpowered mountain board some years back and and decided to use this as the starting point.

Parts
1 x home made mountain board
2 x Turnigy SK3 6354 260kv motors
2 x Hobbyking 150A speed controllers
1 x Hobbyking trigger grip car controller
2 x 5800mAh Zippy batteries
2 x 10 tooth 6mm motor sprockets
2 x 57 tooth 6mm wheel sprockets
2 x cell log 8m battery monitors
2 x ducted fans

Finished board

Electrics

Drive

One of the ducted fans is going the wrong way I know but it does provide a reasonable amount of cooling and is far better than not having it there.

The cell monitors are in the battery box in the middle of the board, they turn the LEDs on the box off if there is a problem. I was going to cut the power if there was an issue but that would stop the electric brakes working.

Tested it works well, the drive knocks a bit when pulling away untill the motors get sync but nothing to bad, would not want to try pulling away up hill. Top speed is around 20mph, speed wobble is quite high but think that just needs getting used to. Not sure of the range yet, my phone GPS did not capture the whole ride.

Adding hall sensors to the motors is in progress, currently machining up the mounts. This should fix the pulling away issues hopefully.

Every one who has tried it seams to want one, me and a mate are currently in the process of making one for him.

[EBJ]

Looks pretty slick.
I like the "bolt-on" motor-mounts and battery-box.

Too bad about the cogging, that seems to be the #1 issue with all of these builds.
Once you get past the initial cogging though, how is the power ?

I'm a little concerned how hot those motors will get, and whether or not that is too hot for the plastic fan housings. What do you think ?
...and don't those ESC's need some breathing room ? or is the box only for when "in mud" ?

Nice work.
Thanks for sharing!
-now go get some video footage for us

[Mattchoooooooo]

Thanks for the positive comments EBJ,

After the cogging the power is great, under very hard acceleration it has lost sync once, that was pulling the trigger to the stop from a rolling start. I think I need some more practise before I can really use all the power.

The motor fans should be ok, I have not found the motors get too hot but that may change when I get more confident and start using more power. The fans do give significant cooling, will just have to see how they go.

As for the cover over the ESCs there is a 10-15mm gap all the way around the bottom to let them breathe, its just to keep the spray & mud off. It may come off in the summer but for now with temps around 10°C out its no problem.

Will get some video soon, better get some practice first so I look go in it though!

[Uvedovle]

Good Job!!!, i'm collecting some money for build my own

I already drive an already made ones but i need two wheels traction...

[Ben90]

Looks pretty cool. I'm currently collecting money and parts for my own board, which will probably be designed like yours (but i guess it will be more ghettoish-looking, as it is my first try ). It will probably be like some prius cells, wooden board and mountainboard axis and wheels, driven by 2 brushed motors, all for simplicity, as this will be my first electric project.

How are you steering it? If you got different rpms on left and right motor, would this be enough to archive a turn radius?

[EBJ]

How are you steering it? If you got different rpms on left and right motor, would this be enough to archive a turn radius?

all of the electric skateboards I have seen thusfar steer just like regular skateboards.
(lean to turn).
As long as you don't have a solid axle connecting both rear tires it should turn without any problems.

[Mattchoooooooo]

As EBJ says lean to steer as you would on an un-powered board. I did make a skate board (10 years ago now) with the two rear drive wheels on a solid axle, it would not turn, so ended up being one wheel drive.

Me and a friend went out on our boards today and had a few problems, firstly it looks like his radio connection to the ESC is dodgy as the motor would not stop the same thing happens if you unplug the radio gear from the ESC as the same time. I had to go after his runaway board on mine! The ESC on his board keeps getting sync loss problems under heavy ish acceleration and throwing my mate from his board, not sure way this should keep happening but hopefully the halls will help with this, anyone else had similar problems with these controllers (Hobby King 150A car ESC)?

My board managed to detach 4 magnets and grind them on the stator, not too badly damaged. I have glued them back in place, will have to see how well they hold. Surprisingly even with 4 magnets out of position the board still performed well!

[Ben90]

Ok, thanks.
What I dont understand from all my reading until now is, is there any standardized format for fitting sprockets on the tires or will I have to drill my own holes?
Is there any kind of detailed info on combining a sprocket and mountainboard tires? I dont want to buy some, only to find out i cant fix the sprocket onto it.

[sk8norcal]

don't think there are any standards,
might be easier to buy premade ones,

most electric mountainboards use 10" tires,
this one uses belt , there are chain version too...
http://www.e-glide.com/index.php?option ... &Itemid=90

this one uses a standard mountainboard hub, 8" tires, using chain,
http://www.e-glide.com/components/com_v ... G_0658.jpg

[Ben90]

Thank you, this was exactly what i was looking for, i hope i find some shop like this in europe, now i have the idea.

[Mattchoooooooo]

I got my chain and sprockets from here
http://www.technobotsonline.com/index.p ... ory_id=193
You can specify machining work you may require as well if you can't do it yourself. You can find sprockets cheaper on e-bay but they don't offer the machining.

[milesinfront]

I got my chain and sprockets from here
http://www.technobotsonline.com/index.p ... ory_id=193
You can specify machining work you may require as well if you can't do it yourself. You can find sprockets cheaper on e-bay but they don't offer the machining.

BEST LINK EVER!!! Thanks, now my drive sprockets are a simple 'bolt-on' job....

[Mattchoooooooo]

I managed to get the hall sensors working on my friends board, however I think they where slightly out, going up a steep hill the motor started to smoke and has burnt out one of the phases. The board was using a single 6374 motor, I had adjusted the sensor to the lowest no load current of approx 2amps. Not sure if it was the halls set up wrong, going up the steep hill on only one motor or a controller fault, it had gone up the same hill a week before without problems, any ideas? Has anyone else used hall sensors on the hobbyking 150A controllers with success?

[Mattchoooooooo]

A video of one of the first outings

[EBJ]

thanks for the video... looks like you bailed right at the end ??

[Mattchoooooooo]

No did not bail, it was filmed on a camera phone. My mate was just trying to turn the camera off at the end.

[walls99]

One of the ducted fans is going the wrong way I know but it does provide a reasonable amount of cooling and is far better than not having it there.

Nice cooling solution!

I need to cool a SK3 6374, where did you get your ducted fans from? Thanks.

[Mattchoooooooo]

The ducted fans where from Giant Cod, now called Giant Shark, just search for them on Google. The Fans where about £3.00 each and turned up next day.