You don't know til you try . . .


Mobility Scooter eCarts conversion

, posted: 30-Jun-2014 19:58

After seeing how cheap mobility scooters were going for I decided to try and turn one into a little electric cart for the 'kids'.
Mechanically they would be worlds better than the plastic kids ride on toys you can get.

eg
https://toyshouse.co.nz/?cms_do=sale&sale_do=sale_show_one_product&product_id=2037


I wanted a 4 wheel model, 3 just wasn't going to cut it.

Picked up one for $100 ish.


Cosmetically it was a little rough.
Frame OK.
Batteries were dead.
Controller had a fault.
Motor OK.
Tyres OK.

The important bits were ok.
Frame, Motor, Tyres.

Due to the age of the system, there was not many troubleshooting documents to be found on the interweb.

I also wanted to run it at 36V, which the stock controller would not be happy with.
Going diy you do loose some of the nice built in features of the controller, unless you buy another with those features.
-Over current protection.
-Regenerative braking.
-Speed regulation
-lots of others
Something with these features is about us$230 landed
http://kellycontroller.com/brushed-motor-control.php
KDZ48201

The controller was stripped down to see what was inside.


12 years old? Look's like new :)

H-Bridge Mosfets were rated to 60V. P60NE0
There were 2 Driver ICs. ir2104
We will be able to reuse this part of the controller.

The drivers make it much safer on the hobbyist since you can't short the battery by setting the wrong Mosfets on.

There was a voltage regulator onboard (7805) but I could not easily figure out how to turn it on.
And didn't want to risk breaking anything else on the board in case I want to use it later on.

Cut the signal traces to the H-Bridge drivers.
Supply control signals and whola.
Working motor controller.


Bits used
-12v Regulator
LM317, might bump it up to 15v.
Or change for a DC-DC to maximise efficiency.
-Arduino ProMini v2 (Clone, m168)
-Pedals from a computer steering wheel racing set.
-Battery will be a Lithium Polymer (LiPo) pack from Hobbyking.
us$116 landed for a 33.3v(9s) 5.8Ah
Top speed should be 15-20kp/h
At low speed for the kids we should get 30-45 mins runtime.

Currently the program on the Arduino is pretty simple.
Push accelerator pedal to go.
Let go to coast.
Push brake to stop.

To potentially add
-Reverse.
Pretty simple in code.
Just need to add a switch.
-Boost button.
Low speed with a 10 second full speed boost available every few minutes.
Make racing interesting.
-Adjustable max speed.
So multiple carts can be set to the same max speed.
During a race it will be driver skill that determines the winner.


Other people have put petrol motors in theirs.
I stayed with electric to keep the noise/maintenance/risk down.
A friend is helping with the metalwork/fabrication side.

Can do a more detailed write up if 3+ GZ members are interested. :)

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Comment by richms, on 1-Jul-2014 20:41

Wow, I had no idea those scooter things were so cheap. I was wanting to roboticise a mower some time ago but gave up with the cost of motors etc and decided that weedkiller was a faster easier option.

Those only being $100 might make me revisit that sometime.


Author's note by MrWestie, on 1-Jul-2014 20:46

Now that you mention it, have you seen the Robomowers the council are using on the motorways? I think one of http://www.slope-mower.com/  There is a guy walking behind it so I think it is still in the trial stages.


Comment by benokobi, on 1-Jul-2014 21:02

My Dad made my brothers and I one years ago. Mobility cart motor hooked up to batteries in the front and controls for indicators, lights and reverse with levers.


Comment by benokobi, on 1-Jul-2014 21:05

I can post some pictures if anyone is interested.


Author's note by MrWestie, on 1-Jul-2014 21:09

benokobi, that would be great  if you could post the pics :)


Comment by mcraenz, on 6-Jul-2014 08:56

Great stuff. Keep it coming.


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