"The Blue monster'' - EMTB | Flexy Deck | Skate Trucks | SK3 192kv 6374 | Diy Clamp | 6s 8ah Sony VTC4 | FVT 120

Hi there! Been a regular user of this forum for quite some time… most of the longer car journeys I had as passanger during my 4 month period of DIY Board Building Research Process was spent searching and reading news / stuff on the forum!

Here’s how it looks when charging:

65T (15mm) - Pulley sent from USA, thanks @Kaly for helping to get it

Background info about the build

Concerning the Motor choice:

Originally I intended to go with 245kv or 213kv motors… Things turned out quite slow (on the hobbyking restock of items)… so once the 192kv appearead, I grabbed it while I still could… (too bad a week later the 245kv and 213kv did came in stock… sorry, too late)…

Anyways, Im quite happy I went with 192kv afterall…

it is bigger and I have a better confidence it will go stronger because of its size and increased amp rating and also because it can be sensorer or easly used for higher voltage system with no problem…

How I dealt with mechanical part:

Ok, to continue the ‘‘descriptive build log’’ process… - The biggest pain in the A## was with motor mount and wheel pulley of course… Originally I thought about just cutting the mount out of aluminium as I had the plans sent to me already, I just had to modify them a bit…

Later it turned out it was quite hard to find a suitable piece of aluminium (in 10mm widht)… and by going the ‘‘commercial’’ route I would pay a lot… probably around 90$ just to fabricate the part in some cnc / waterjet shop…

– Time went on… it turned out it is quicker to just make the mount with some makeshift piecies of metal..

Unfortunately I dont have a vast documentation on how the mount was made… I can only publish upon request how it looks from different view

Wheel pulley was mounted by a friend’s father, who got a lathe, he basically cut the adapter plate out of some plastic.

Battery Build

. Other than that - had the chance to assemble the battery pack myself…

Had 20 cell, 10S2P VTC 4 pack available, split it in two, now had 5S2P Pack… by joining them together I got 5S 4P pack, had to add another row of 4 cells, to get 6S 4P pack…

The pack is originally from the ‘‘power tool’’ market, I had the chance to get it, as one E-bike battery builder had acquired it from one of his sources of batteries.

Unfortunately these are early build pics and I dont have much more, I later added balance cables and finished the parallel rail (the one which is not made yet in the last pic)

Energy Use / Power stats:

. So far it seems that the board is consuming about 19-20wh per km.

Theoretical capacity of the battery is 8000-8400mah.

Max I’ve discharged so far is about: ~7600mah, so a room of about 400-800mah.

Battery is charged only till 4.1V (the standard for balance charger), I usually try to stop riding at around 3.5v per cell (around 21v) and it corresponds to about 10% from what turnigy charger sees.

Charger specs:

. Right now Im using only Turnigy Accucel 6, 80W 10A charger.

Though, it is not posible to charge at 10A at 6s… I could get only about 3A at 6s (24.6v).

For now, I have to charge at 2.5A, so it takes a rather long time to charge the battery, if over 7ah is consumed… It takes around 3h 15min, to charge about 7ah.

This is because I use quite low wattage laptop charger, it is rated at 72W, puts out 16v at 4.5A maximum, so Im probably almost pushing it and it gets hot

So there’s still room to get about 0.5A, If I had a better PSU.

FVT 120 esc

So far it has held up great! Max my wattmeter has shown is that I’ve reached 60A peak power…

During normal cruising, when I looked at wattmeter, it stayed in 5-20A range, so as the fan is working all the time non-stop, I suspect it gets no problem holding the load.

Acceleration is set to soft, so I dont get the board pulling away from my feet, braking is quite good but the belt is not tensioned enough to truly test the brakes…

it brakes hard if you allow it, so it is still a good advice to push gently on the brakes.

Deck choice:


I chose the board basically from the looks and the wheels.

The real name for the deck is Scrub Silver Reef series II.

It is quite flexy, got only 9ply (that’s what the internet page says, have not counted myself)

My future scenario is to use a standard skateboard deck, with about 28’’ (~70cm) in size

My current deck is about 36’’ in size now, plus add the motor/mount and it is about 42.5’’ in size, tires included.

Quite a ‘‘boat’’ I might say :smiley:

BTW, here’s a promo pic of how It soon might turn out:

This is not a skateboard deck but a shorter mountainboard’s one. It is about 32’’ in size.

Remote controller:

. I use a standard mini-remote, works quite good, I made some '‘mods’'

  • Removed the turning wheel
  • Cut through plastic to allow the trigger swing more further than it originally is

Extra features, perhaps, could be: ‘‘deadman’‘s switch’’. Perhaps also a little light. Turn off button could have been more easy to reach, as it is quite hard to always turn it off, as it is in a size of a fingernail :smiley:

Enclosure options:

. I originally wanted to place the battery in the middle and possibly make a shape of the enclosure something like this:

But things got hasty with the mechanical part, so I ended up placing the battery at the end… on a rather springy metal sheet

Cons: It looks rather bulky (the way it is now). but at least it partly hides the motor…

Though, it also does shake like crazy if the road is bumpy and for now I’ve got it covered with just some colored paper for it to look a little bit better.

The right way to do it would probably be to print and mount 3d printed box on it.

Overall stats:

. Max speed around: 35kph/20mph Board Weight: around 11kg / 24lbs

Possible distance to do (at ~15kph): ~8-12km / 6-7mi Turning radius: Quite bad (long board, low risers, stiff bushings) Charge time: 3+ hours

Gearing ratio: 1:4.33 (15T : 65T) Torque: Quite good (less heavy person can start from standstill) Rider weight: around 195 lbs / 88kg (possibly better stats for lighter riders)

Final words/ comments about the build:

That’'s it for now. I just wanted to make somewhat detailed build log… also with energy use data… Sorry for removing the motor plate pic, I will probably try to improve it and while I have not done it… there’s not much nice to show :smiley:


Have you risen it yet as the motor plate looks very thin and probably bend if it already hasn’t. But looking good and on the way to a good mtb

yeh, plate needs some more thickness for sure! You know how it is with all of these ‘‘temporary’’ solutions… they make to live for longer than indended :smiley:

I have updated the build log… so if someone missed the log itself and now finds it interesting, you’'re welcome!

Sorry for the lack of technical / mechanical pics… It’s still sort of a ongoing build, so I have not finished all the crooks and crannies of it…