The New and Improved Brushless Electric Scooter Power System Guide

In 2008, I put together a guide on Instructables about upgrading the power system of your small personal electric vehicle . It was a primer on the basics of an electric vehicle power system and offered resources and tips specific to compact electric scooter conversion. As of right now, it has a solid 5 rating - I didn't know you could write that much on Instructables without telling anyone how to build anything and still receive perfect reviews.

I am delighted to report that in 2011, three years after the fact, that putting together a compact, powerful, and efficient electric vehicle drivetrain for local commutes (such as your campus, neighborhood, or urban area) using both R/C hobby hardware and specialized EV components is now cheaper and easier than ever. Price competition, new technologies, and just plain increased availability of fabrication and material resources means that building an electric personal transport device is now within the capabilities of just about everyone.

I will assume that you already know the fundamental parts of an EV or have built them before. If not, you're welcome to refer to my previous Instructable on this topic (linked above), or check out one of the many great Instructables on EV systems. This Instructable is intended as a conglomeration of resources, and so will discuss the pros and cons of component choices, specific vendors, design strategies, and other high-level considerations. It will also offer tips and tricks that I've found or had passed on to me pertaining to building small electric scooters. The guide will be overtly calibrated towards said scooters, since I favor them over electric bicycles, though much of the advice is just as pertinent to e-bikes. It should also be helpful for the occasional odd electric skateboard or other unconventional vehicle.

The format of the Instructable will primarily be a page or two on each primary component of an EV - such as the motor, controller, battery, and drivetrain (and associated mechanics).Then I'll present some designs that have emerged as being relatively easy to execute and fabrication advice for fully custom vehicles (i.e. not conversions).

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grmccray3 months ago

It looks like the above named A123 ALM_12v7 drop in batteries are available from:

for $130.00

roboman24448 months ago
What is the pinout for the standard, RC esc sensor connector?
rf1 year ago
Wonderful instructable. Have been giving it some thought for a bit and wondering why you haven't considered building your own ESC. From your descriptions a sensorless controller suitable for our purposes seems very doable, but not available within the R/C airplane realm. We need a custom, self-starting, sensorless ESC. Other's have made them.

Once you have the basics together fine-tuning becomes possible. Seems like the perfect solution to a host of problems. Perhaps the springboard to designs otherwise out of reach.
augurolo1 year ago
Thanks for your instructable. It's very interesting and complete but I have a, may be, stupid question. I'm planning to put sensors in an outrunner as well and wanted to know how to tie the sensors to the ESC. There seems to be a standard 6 pin connector shared between the different ESC models. How do I wire the sensors to this connector?
Grey_Wolfe1 year ago
This is a pretty sweet little scooter, might make one for my son if he starts behaving again. lol

I am legitimately trying to find that gas motor which you showed but did not use.

Can you tell me where you found it? I can only find electric models, which are great but not appropriate for my current project.

jazzenjohn1 year ago
I found a good place to get thick very flexible 8 and 4 gauge wire is the local car stereo center. Th 8 gauge I used cost $1 per foot. They had 4 gauge but it was much more expensive.
NewbOzzi1 year ago
Wow after reading this article now I'm building a scooter.
Bad influence I think..
Welding and machining I get but the electrics are not so much my thing :(

I bought 2 motors

Constant: 259Kv
Battery: 10Cell Lipo
Operating Current: 25-60A
Peak Current: 72A(15sec)

Here is the problem.. Do I run one and have a spare or use them both?
If both what would be the best way?
If you run both you need a controller for each. Now this may sound easy but you need to be careful to set up each esc the same and use the exact same model of esc and motor or one motor will do more work. Now unless you want to push more than 200 lbs around at 20 mph or more one motor should be sufficient as long as you use the gearing equation from this article as to not burn up your motor. Good luck and feel welcome to ask any questions you want to.
kaihattan1 year ago
Hobbyking now sells 20C four cell 5 Ah lipo packs from the US warehouse for about $25 per pack:
kaihattan1 year ago
Could I maybe use a large pvc pipe to hold the hall effect sensors?
kaihattan1 year ago
How exactly do you back install hall effect sensors in a motor? I am trying to make an electric motorcycle and want to use a kelly controller. I have a Turnigy 80-100-A 180 KV brushless outrunner (the same class that is on the scooter in this instructable) and have had a really hard time figuring out how to install sensors. I am also having a hard time figuring out how this motor is wound.
Any help would be greatly appreciated, thanks in advance.
teamtestbot (author)  kaihattan1 year ago
It is extremely difficult to install *internal* sensors onto a mystery motor (of which you do not know the internal winding pattern). The C80 series is also very difficult to discern because they require so much current.

Usually, you would run current through two phase wires ("line to line") and use a test magnet to observe which poles are polarized in which directions - they should always be alternating from tooth to tooth and there should always be 8 of them on in total. Using this and the process of elimination you can separate the 12 teeth of the stator into 3 groups of 4 teeth which you can call "A", "B", and "C", which are associated with one of the three phase wires. Then, the Hall sensors are placed *between* 2 teeth of *different* phases.

Because the C80s have a very low resistance and few turns, you need either a ton of current or a sensitive magnetometer to determine the direction of the stator field.

Using external Hall sensors on the C80s is possibly the easiest solution.

Thank you for the info, I have tried to run current through the different phases but I could not get enough current to get discernible results. I am thinking of just rewinding the motor so I know where the different phases are. Unfortunately I do not have access to anything to make an external mount for hall effect sensors. Do you know of a website that could make a mount for me? I also do not have any experience using CAD software. Another question I have is do all hall effect sensors have the same wiring scheme? The website I got mine from did not tell me which lead is which.
guyst1 year ago
a bit for the sake of accuracy: when you refer to "convection", you actualy mean free convection(no air speed), as opposed to forced convection.
other than that petty note, its a great article and im learning why i shouldnt have bought the esc that i have...
Just wanted to say a quick thanks for this instructable. It's the detail all in the one place that i have been searching for, for years. Thanks for confirmation of R/C parts as well and the technical detail.
Can you use the sensored kelly controllers with a sensorless motor?
teamtestbot (author)  kaiinstructables2 years ago
Not the KBS - Kelly does have the KSL line which is sensorless, but I have not heard vehicle stories about them nor know what settings they can manipulate (e.g. ramp-up time, initial current, etc.). And they're huge - they're full-size Kelly cases.
bratan2 years ago
Great tips, especially about bore size changing! Thanks for taking time and explaining this!
If I'm going to use LiFePo4 batteries from HK, will I need to include a battery management system when discharging and/or charging? Great instructable, by the way.
You wouldn't necessarily need one, but as long as you are getting a Li batt from Hobbyking, pick up a balancing charger along with it. It will be there when you do need it.

I do not think HK cells are as robust as A123s, and they definitely get out of balance faster. It is a good idea to have the balance connector accessible and to periodically throw them on the balance charger.
hgalindo2 years ago
NIce Work!, do you have any video to see how it works?
m0ng00se2 years ago

Is a good piece of software to calculate speed etc, I got the link from
SimonArthur2 years ago
Double check your info on GT belts. They're made by Gates, who rate them for much higher load than HTD belts. The belts have round teeth and are compatible with HTD sprockets, but supposedly work better with GT sprockets.

I know this because I've been working on the belt drive system for you-know-what.
m0ng00se2 years ago
Great tutorial,
I'm in the process of building up my e-scooter I brought for $20 and was just wondering what are your thoughts on 3d printed parts for spurs and sprockets with chain for a scooter?

teamtestbot (author)  m0ng00se2 years ago
Hey Larry,

I wouldn't expect a 3DP sprocket to last very long due to it interfacing with metal. I have, however, played with 3DP timing belt pulleys. I wouldn't put more than 2-300w through a 5MM printed pulley, though.
Spokehedz2 years ago
WOW that is an absolute ton of information. THANK YOU!

Also, I find that for twisting the wires, it's better if you have a minimum of two people (three is better) and to twist all your wire up at once.


Two people have drills with the wires chucked into the ends. Both drills are in the same direction.

Ends of the wires not in the chucks are securely connected together. I use a ziptie with the wires doubled over.

The length of the wire is stretched out (This is where the third person helps) but not touching the ground and connected to something like an eyehook or something. The wires must be FREE to spin in the air and not touch anything.

Then you simply spin the drills at the same RPM (two identical drills set on 'low' is best) and you watch as the wire begins to twist itself into a neat little cable without any kinks. The third person can hold the wire where the twist is coming together to help it form nice and tight.

I have made bundles of CAT-5 cables over 25' long with this method and it only takes about 5mins to get the setup and everybody schooled in their job. With good quality silicone wire and good helpers, it can go even faster.
I've done this on my own many times. Clamp one end, use a drill at the other end and have at it. Sometimes I'll use a heat gun to anneal the insulation, but sometimes I'll just let it sit for a minute or deal with it unraveling a little. A heat gun is easier if you have a second person, but I've used the weight of a drill to keep the wire tensioned while I run a heat gun over it.

Make sure you have plenty of slack to start with, the longer the wires the shorter the bundle you make will get (since the wires travel in spirals instead of straight lines)
By twisting both wires in the same direction, they will wrap themselves and stay wrapped--no heating required. They also don't want to coil up on one another. They lay flat, and coil just like a normal cable.

This is an ancient rope/twine making technique.

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