Another Newb trying to make an E-Board :D

[Harlequin Hawk]

Greetings all,

I am a Trying to build an Mountain/Carving E-Board and this will be my 1st Attempt. I have already picked out a few of the parts, but have yet to pick others and would much appreciate any feedback. I am Trying to spend money Wisely, Important stuff i am willing to spend more on otherwise ill go cheap. Also for now im only getting one motor but will upgrade to 2 eventually. Also i have a Machinists friend who will be milling a Motor Mount for me.

Here are the parts i have/planning to get so far.

Motor:
Turnigy Aerodrive SK3 - 6374-149kv Brushless Outrunner Motor (US Warehouse) . I wanted a high Torque Motor and would offset it with a 3:1 Ratio gear setting for higher speeds, is what i read around the web would be right?

Transmitter/Receiver :
HobbyKing® ™HK-GT2B 3CH 2.4GHz Transmitter and Receiver w/Rechargable Li-i (US Warehouse) . This is what i read everyone else uses. Its cheap and works.

Gearing : ~3:~1
Small Pulley 5M25T
Large Pulley 80 Tooth Drive Belt Cog 12.7cm/5inch Diameter Machinists Friend will be drilling the holes and possibly taking out the excess metal.
550mm-5m-15mm Belt

I do Realize that I could have gone for Less Teeth and same Ratio of gears, or did i fub the math on this XP ? but these are cheap so there you go lol XD

This is where i need help.

ESC/VESC:
From what i have read here I want atleast 20% above the motors peak. In my case 70amp is my motors peak, so 84 amp minimum per motor? And since ill be getting 2 motors eventually i was wondering if i could get like a 200amp ESC and hook up 2 motors to the same ESC? If not any suggestions for a moderatly priced ESC would be very welcome. Any advise really would be great.

Batteries:
So ive read here that Voltage gives the motor "Power" while Mah is how long that battery will last. but whats the C=Discharge rate mean? I am weary of pricing and there are so many to choose from. Lipoly, nimh, nanotech BLARG!!! I am going to keep looking and narrowing them down but any suggestions/info here, are again very welcome

I think that is everything.

Ill also add the Board im making just in case. I think its pretty good =D

Mountainboard Deck, Ten Ply Canadian Maple, Drilled Again Mr Cheap wins the day lol

Trampa trucks I wanted good Trucks that would last so i splurged a bit here.

Trampa Hypa Hubs I wanted the Wheels i bought to fit without issue so i also purchased the wheels, spacers, and Bearings from Trampa. The cheapest ones of course lol.

 

[Harlequin Hawk]

Just found this on ebay 12V 20000mAh Multi-Function Car Jump Starter Power Booster Battery Charger New S could i buy 2 of these, strip out the batteries and connect them in Series to get 20000mah at 24v? or will this not work?

 

[amberwolf]

If you look around the forum there are a number of threads about those things.

The cells are highly unlikely to be 20Ah cells. There are probably 4 cells in series, each of which is at best 5Ah, and the marketing people for stuff like that think it's really cool to lie and add all the Ah for series cells, which isn't how it works.

You'd have to actually buy one, then test it for actual capacity, and then disassemble it to find out how it's built, to know what they actually put in there.


Personally I doubt it could actually jumpstart a car---it *might* be able to trickle charge the car's battery enough to let the actual car battery start the car.... (see previous discussions about these things for more info on that).


There *are* units out there that *can* actually do what they say...see Boystonstu's threads about his Walmart units.

 

[Ianhill]

C rating is the discharge rate that a battery can provide it is given in a figure of peak which is normally 10 secind bursts or continuous a sustainable load through the discharge cycle one C is equal to the Ah stored within the pack so if the pack is 10c and 5000mah this means the pack can deliver 10C × 5Ah = 50A discharge nominal and the pack will deliver its capacity.
If a battery is used beyond its rated c rating or on its limit it will create a lot of heat and its capacity will also diminish so say a 5000mah battery with 10c at 150a discharge may only deliver 1000mah before its to hot to continue and the voltage sags beyond controller low voltage cutoffs.

As mentioned above those starter booster packs are a way of recycling junk cells from china, when it comes to battery's it number 1 even before the motor and controller its at the heart of the project and makes everything beat so pick good battery's for your needs otherwise you can guarantee a headache.

 

[Chalo]

I do Realize that I could have gone for Less Teeth

Yep, with an e-board, that's what you're going for. That, and knocking all your freshly learned electrical knowledge right back out of your head.

[youtube]ZIJo7K_9mkU[/youtube]

 

[Harlequin Hawk]

Thanks for the Battery heads up Amberwolf and Ianhill! as i was trying to find more info here i found a thread specifically for batteries and there are some sweet stuff over there, im currently looking at this project Another No Solder/Weld 18650 Build (Updated 03/09/2014) which looks up-gradable and very stylish. The parts are cheap except for the 18650 batteries. 3000mah batteries go for about 7.50 a piece on amazon which by it self aint bad, but if i consider what Ianhill just told me ill need atleast 14000mah for the x2 70amp motors i want to use so...doingmath...i want at the least a 6s5p / 22.2v with 15000mah thats...30 batteries? thats about $225? thats alot of money for batteries lol arg. It will be awhile before i can save the money for that, in the mean time ill keep looking for alternatives.

Chalo

Yep, with an e-board, that's what you're going for. That, and knocking all your freshly learned electrical knowledge right back out of your head.

Are you saying i should scrap the gears i got and go for smaller ones? besides being cheap, i read that bigger gears help the belt last longer? so i figured if i got a torque'y motor (149kv) it wouldnt matter?

Again Thanks for all the advise!!

 

[WeeChumlee]

I have never built a E-MTB myself but I would imagine that if you are going for 6S that 15AH would be in the region that you would want.
That is also a big heavy board, with big wheels and running in difficult terrain - so you will want a battery and an ESC that can deliver good punch.
Look at the builds of a guy here called "nowind". There you will have everything you will need to know.

Oh, and you need one ESC per motor - so no 200A ESC for two motors.

 

[Harlequin Hawk]

Look at the builds of a guy here called "nowind". There you will have everything you will need to know.

Oh, and you need one ESC per motor - so no 200A ESC for two motors.

I checked them out and your right nowinds boards are impressive, very nice!

1 ESC per motor, roger that. I thought i could take a short cut but i know how finicky electrical things can be thats why i asked 1st. Thanks!

Speaking of the ESC ive just read that the ESC needs to be able to handle the amount of poles in the motor?(12 poles in the motor im going to use) i am going to continue researching and finding out more but any suggestions on a ESC would be very welcome, Thanks again!

 

[WeeChumlee]

Regarding the ESC.
As you are building an EMTB it will require torque and punch. (So good ESC and good batteries)
As good as the VESC is I personally do not think it is the best for this application.
If the max voltage is 8S then I would suggest the EZRUN MAX6. Great punch but unfortunately not so great whine from motor under braking. This annoyed me on my street board but on an EMTB maybe not so much of an issue. For voltages up to 12S then I would suggest the Torqueboards 12 S ESC. (Personally never used it but use a very similar one and find it great)