New builder- electric off road

[TreePirate]

Hi folks just joined today.
Have planned an electric off road junior kart in my head for 30 years. I now have the time to make one for my kids to enjoy.
I was a machine engineer and can weld.
My plan is to build an off roader capable of around 10-15kph and will have double wishbone A-arms all round.
I was planning to build suspension arms but i now have a 90cc mid side quad front end with 16" wheels and ackerman steering and drum brakes on hubs.
Rear end i will copy the A-arms and struts and add a 3 piece universal joint drive shaft.
Any opinions so far?
All criticism will be accepted.
Right thats as far as my skills take me so pls help with....
1) I have access to a Razor E100 scooter... Will this be powerfull enough or should i buy a my1020 motor?
2) What gearing/ belt or cog ratio should i be looking for to get 10-15kph speed with 16" tyres
Thanks all

 

[jrbrtsn]

TreePirate,
if I were you, I'd keep it lightweight and simple. Unless you spend thousands on the electric drivetrain, you will have to settle for less than about two horsepower. Forget suspension, you probably won't be going fast enough to need it anyway.

 

[TreePirate]

Im going to stick with chasis and suspension incase i change to a petrol motor as the kids get older.
I have read through as much as i can and so far as im new to electric motors.
If any calculations are wrong pls tell me.
Kart with passanger- 110kg (250 pounds)
Wheels- 400mm (16 inch)
Gearing- 1-8
Motor- 36v
1000 watts
30 amps
Batterys- 3x 12v 30amp

any ideas where i can motor and batterys ? Maybe wheel chair or golf buggy?
Thanks

 

[jrbrtsn]

If it's an electric kart, and you use lead-acid batteries, you're probably going to have around 120 lbs just in the three batteries. A kart chassis with full suspension, wheels, tires, brake, and drivetrain could easily run upwards of 250 lbs. So, I would estimate the fully assembled kart with batteries and passenger closer to 500 lbs. Your electric motor will be about 80% efficient, so with 1000 watt inputs you'll have about 800 watts out, which is just about 1 horsepower. I figure it would run a little faster than a golf cart.

 

[Toycrusher]

Your best bet is to start with a Golf cart. I have modified a power wheels for my kids using two MY1016 motors at 36v with independent 800 watt controllers. It has great torque and moves around 10 - 11 mph with 16" wheels, which is in your target range.

However, it's built from mostly plastic, only a fraction of the weight of your kart. It has significant gear reduction, somewhere around 12:1

Go for it and be prepared to make changes

 

[jrbrtsn]

Here are some similar vehicles available for purchase:
http://www.amazon.com/s/ref=nb_sb_ss_i_3_7?url=search-alias%3Dtoys-and-games&field-keywords=go+kart+electric&sprefix=go+kart%2Cundefined%2C373&rh=n%3A165793011%2Ck%3Ago+kart+electric

Here is a source for electric drivetrain parts & batteries:
http://www.monsterscooterparts.com/

 

[TreePirate]

Wow this a total awakening to the reality of dc motors and kart building in general. I supppose everyone starts off thinking of speeding along silently for a few hundred pounds.
I think ive scored a 36v motor off our local forklift mechanic. Hopefully it will be at least 1hp.
He was interested in the build so hopefully get him to check out my circuit before i blow my top off.
Ill take pics as soon as i get all the parts collected up.
Thanks for advice so far lads...
The sub frame will be a space frame design making the use of triangles rather than a ladder style.
What is the smallest size of steel anyone has Successfully used to build a chassis like that?

---------- Post added at 08:47 PM ---------- Previous post was at 08:29 PM ----------

Im thinking 20 x 20mm 2mm wall.
Roughly 3/4" x 3/4" x 1/16

---------- Post added at 08:55 PM ---------- Previous post was at 08:47 PM ----------

Weight= 1.12 Kg per meter
Weight= 3/4 pound per foot

---------- Post added at 09:01 PM ---------- Previous post was at 08:55 PM ----------

Im roughly estimating 12 meters or 40 foot of steel maximum
Giving 15kg bare frame or 33pound.

---------- Post added at 09:05 PM ---------- Previous post was at 09:01 PM ----------

http://www.4qd.co.uk/faq/current.html Found good site for speed and power for dc.