Small, Light and Cheap - My First Single Motor Eboard Build

[Magnus_Volk]

I'm attempting to build a small, light and cheap eboard using my very limited knowledge of electronics, mechanical engineering and skateboarding. I'm a hacker at heart, so I'm hoping that my love of tinkering and basic trial and error will get me through this project.

This is mostly based on the torqueboards' post here: http://endless-sphere.com/forums/viewtopic.php?f=35&t=54963&p=831538#p831538

I'm waiting until payday to get the first round of components, but as soon as I have the money here is my shopping list:

Deck
I'm going to reuse the deck from a mini cruiser I got for Christmas: http://www.amazon.co.uk/Osprey-Stripe-Mini-Cruiser-Multicoloured/dp/B009FUN7G0/ref=sr_1_7?ie=UTF8&qid=1387130997&sr=8-7&keywords=mini+cruiser

Trucks
$155 - 180mm Paris Trucks (wheels, spacers, bearings, hardware) with Single Welded Motor Mount (from torqueboards - http://endless-sphere.com/forums/viewtopic.php?f=35&t=54963&p=831538#p831538)

Motor
$72 - Turnigy Aerodrive SK3 - 6364-245kv Brushless Outrunner Motor - http://hobbyking.com/hobbyking/store/__18128__Turnigy_Aerodrive_SK3_6364_245kv_Brushless_Outrunner_Motor.html

Battery
ZIPPY Flightmax 5000mAh 3S1P 30C - http://www.hobbyking.com/hobbyking/store/__8587__zippy_flightmax_5000mah_3s1p_30c.html

Battery Charger
IMAX B6 50W 5A Charger/Discharger 1-6 Cells - http://www.hobbyking.com/hobbyking/store/__28146__IMAX_B6_50W_5A_Charger_Discharger_1_6_Cells_GENUINE_UK_Warehouse_.html

Power Supply
Hobbyking 105W 15V/7A Switching DC Power Supply - http://www.hobbyking.com/hobbyking/store/__36965__Hobbyking_105W_15V_7A_Switching_DC_Power_Supply_with_UK_plug_UK_Warehouse_.html

ESC
Hobbywing EZRUN-150A-PRO Brushless ESC - http://www.valuehobby.com/hobbywing-ezrun-150a-pro.html

I'd really appreciate a critique of these different parts. I'm willing to spend a little more on electronics if anyone thinks that it'd be worth it. I really have no idea about the electronics side of things so any suggestions for improvements will be greatly appreciated.

I'll post pics of the build when I get started.

 

[torqueboards]

Looks great. You don't have to spend more on electronic parts. Perhaps a better charger if you plan on charging multiple packs and/or want to charge faster.

The EzRun is a good ESC for a single motor.

 

[spinningmagnets]

Add two low-ESR capacitors to the power inputs of the ESC. http://www.endless-sphere.com/forums/viewtopic.php?f=30&t=22194&start=25#p382837

Use two of these ($2 each): http://www.digikey.com/product-detail/en/EEU-FM1H102/P12393-ND/613754

 

[Magnus_Volk]

torqueboards - great, thanks for the feedback!

spinningmagnets - I read the post you linked to but I'm afraid most of it went over my head (I'm new to most of this stuff). Could you explain the reason behind this in a really simple way?

 

[torqueboards]

It's basically a secondary storage unit of power to give your setup a bit more juice when the voltage ripples or sags. It's not expensive to add one. I've included a few links in which you can read up a bit more on it.

https://www.google.com/search?q=capacitor+bank+rc
http://forums.offshoreelectrics.com/showthread.php?27369-Adding-capacitor-banks-to-ESC
http://traxxas.com/forums/showthread.php?8958638-Castle-Creations-CapPack-Capacitor-Bank
http://www.rcgroups.com/forums/showthread.php?t=1754446
http://www.msuk-forum.co.uk/topic/144536-using-a-capacitor-bank-with-150a-esc/
http://www.ultimaterc.com/forums/showthread.php?p=1286134

 

[Magnus_Volk]

Thanks mate. I'll have a read and then maybe order a couple.

 

[beetbocks]

you might want to check out my walk through guide on building a single motor board..
http://www.aliendrivesystems.com/set-up-tips--walkthroughs.html

I have found that a single 50mm motor with a 7s battery is the perfect setup for everyday use with good range and good speeds...

 

[Magnus_Volk]

Thanks for the link beetbocks.

The Turnigy Aerodrive SK3 - 6364-245kv Brushless Outrunner Motor is currently out of stock on HobbyKing. Can anyone recommend a similar replacement? Would something like the following work well with my setup?

http://alienpowersystem.com/shop/50mm/alien-5065-sensored-outrunner-brushless-motor-270kv-2200w/

 

[beetbocks]

Thanks for the link beetbocks.

The Turnigy Aerodrive SK3 - 6364-245kv Brushless Outrunner Motor is currently out of stock on HobbyKing. Can anyone recommend a similar replacement? Would something like the following work well with my setup?

http://alienpowersystem.com/shop/50mm/alien-5065-sensored-outrunner-brushless-motor-270kv-2200w/

yes i use that on my single motor freestyler board- and i love it...its got plenty of power but still maintains a lightweight deck
[youtube]P-3Kflc6-rQ[/youtube]
[youtube]I8aJ3P2yxdg[/youtube]

 

[torqueboards]

Hi Magnus,

Those mounts only fit SK3 63mm. You would have to choose another type of SK3 63mm motor. Alien's 63mm motors wouldn't fit. Are there no 63mm motors available at all?

 

[Magnus_Volk]

Hey,

The following motors are in stock. Which one would you pick?

https://www.hobbyking.com/hobbyking/store/__18127__Turnigy_Aerodrive_SK3_6354_260kv_Brushless_Outrunner_Motor.html
https://www.hobbyking.com/hobbyking/store/__18129__Turnigy_Aerodrive_SK3_6374_192kv_Brushless_Outrunner_Motor.html
https://www.hobbyking.com/hobbyking/store/__18180__Turnigy_Aerodrive_SK3_6364_213kv_Brushless_Outrunner_Motor.html
https://www.hobbyking.com/hobbyking/store/__18181__Turnigy_Aerodrive_SK3_6364_190kv_Brushless_Outrunner_Motor.html

Sorry, I don't really understand how the kv difference will affect performance. Thanks for your help!

 

[beetbocks]

KV is directly related to the rpm of the motor which in turn gives you the calculated top speed..basically the lower the KV.. the lower the top speed but the higher the start up torque..
RPM= KV x V ( cellx 4.2v)
so- 245x 6s ( 6x4.2)
so- 245x 25.2
=6174rpm

270x6s
=270x 25.2
=6804rpm

you see?

 

[torqueboards]

Either is good. The differences are slightly minor.

If you don't care about weight 6374's. If you want lighterweight 6364 or 6354's work.

 

[Hummina Shadeeba]

I think of kv as an internal gearing for the motor.
I still have questions myself about it but this is how I see it:
Ull get the same watts out of a motor of roughly the same size regardless of kv but to make it work efficiently it needs to be matched to the load put on it. Outrunners are roughly 90% efficient internally and then based on the load put on it it'll have a further reduction in efficiency as energy is wasted as heat. What range of Rpms u end up running at and what ur no-load Rpms would be for that motor...I think is what determines a lot of one's efficiency What that range is and if it's simply a linnear relationship with the further u drop Rpms the worse efficiency is how I ..think..it goes
But the bigger your motor the more electrically efficient as there's more wire to transfer the electricity. A thin enough wire and u have a lightbulb which is not what u want

It's generally more efficient to gear the motor down instead of using a lower kv since the low kv is a product of the thinner wires used which won't take as many amps, get too hot, and without a physical gear reduction your relying on just the motor's width(internal leverage) to give torque

 

[beetbocks]

Yes I'd agree with that..it's certainly works like that in practice..

 

[Magnus_Volk]

Hi guys,

I've successfully connected everything up as shown in the image below. However, after running the motor for about 20 seconds the esc starts flashing red. According to the EZrun 150a pro manual (http://www.hobbywing.com/uploadfiles/sx/file/Manual/HW-13-pro-150.pdf) a red flashing light means the input voltage is too low. When I check my battery voltage I get voltage in the 4.1V range, which I understand is normal.

Is my battery/ESC fried?

 

[furp]

There might be more than one thing causing red led blinking. Have you tried running it on 6s?

Just to be on the safe side: push your motor connectors all the way in to avoid accidental shorting.

 

[drmacgyver]

I think you just need to get another of the same battery. Currently you're only running 3s (11.1v), which isn't enough juice. Once you get the second you'll need to wire them in series with one of these: http://www.ebay.com/itm/No-Wire-T-Plug-Deans-Style-Series-RC-Battery-Connector-Adapter-Wireless-/151279966338?pt=Radio_Control_Parts_Accessories&hash=item2338fd1882
So the result will be 2x3s series = 6s (22.2v)

However, I'm not sure if deans connectors are rated high enough for the amperage, so you might need to upgrade to something bulkier, ie: EC5 connectors. (Can someone chime in with more specific info?). Switching out the connectors will require you to solder, which is very simple to learn if you've never done it. Plenty of youtube tutorials on how to solder, and a soldering iron is one of the cheapest items to buy out of all the parts. That's how I learned when I build my board

 

[psychotiller]

http://www.hobbyking.com/hobbyking/...zoUeArF5YjC0mHD-hryZ4Jls94OAENYDghBoCk2_w_wcB

 

[furp]

As said, you will need a different connector, too. Go with xt90, ec 5 or 5mm gold bullet connectors. Have a look at how batteries with 5mm bullet connectors (eg zippy compact 4s 5.8ah) are wired. Having one male and one female connector makes them really easy to connect in series. But if you gonna disconnect the batteries offen, better go with a one piece connector.

First of all, you need another one of those battery and connect them in series for 6s.

And you will need a good and powerful soldering iron plus some solder, maybe even one of those pens to suck away excess solder. Dont bother yourself with a too cheap and weak iron, you will need some juice to solder those big connectors and wires in a reasonable time.

Good luck

 

[Magnus_Volk]

Thanks for all the help! This forum is great

I've ordered another battery and some ec5 connectors so hopefully that will fix my problem. I'll report back. It's amazing how many different types of connectors there are, can't someone decide on a standard I guess it's all good soldering practice though!

I was wondering how you guys monitor your batteries while running. Currenlty I have one of these little battery alarms to test my battery voltage http://www.ebay.co.uk/itm/like/261242051999?limghlpsr=true&hlpv=2&ops=true&viphx=1&hlpht=true&lpid=108&chn=ps&device=c&adtype=pla&crdt=0&ff3=1&ff11=ICEP3.0.0-L&ff12=67&ff13=80&ff14=108&ff19=0 but when I'm up and running I'll need to know when my batteries are low on juice so that I don't burn them out. What's the best way to manage this?

 

[torqueboards]

It's too bad soldering equipment costs too much money. I've enjoyed my Hakko FX888D-23BY but is about $100 bucks for a soldering iron bought on Amazon.

I have a ton of $15-$40 soldering iron's but none of them work great for using a soldering iron multiple times.

As for different connectors, it's mainly used depending on how many amps your pulling and/or using. These are only RC connectors. Imagine all the electrical connectors available

Usually the ESC will monitor the packs and stop/slow down when you are out of battery. You can feel the voltage drop as well usually. If you do use one of those voltage meters don't keep it on the board when the boards off it will end up draining power from one cell only which will ruin your packs eventually.