12v electric gokart not working under load

[steve13]

I have changed a pedal gokart for my grandson into a 12v gokart. It works ok on the bench but will not work on the floor under load. I have changed the controller and add extra 12v 9ah battery in parrel but still will not move?

 

[Sparkwizard]

I would feel around for hot wires and hot connections. Resistance causes heat and hot parts will show loose, corroded or undersize wires and connections.

 

[Whitetrashrocker]

Im gonna guess gear ratios are way off.
Post up some pics of this.
Im sure someone can spot your issue.
Perhaps Functional Artist can help with the pixie wrangling.

Side note: Perhaps we should call him Fiberglass Artist now.

 

[panchothedog]

If it works on the bench but not on the ground, your gear ratio is probably too tall,
or the motor just doesn't produce enough power to move the weight. Like suggested above, lets see some pictures of the tires and the drive train. We can't even guess about what we can't see.

 

[steve13]

If it works on the bench but not on the ground, your gear ratio is probably too tall,
or the motor just doesn't produce enough power to move the weight. Like suggested above, lets see some pictures of the tires and the drive train. We can't even guess about what we can't see.

Im gonna guess gear ratios are way off.
Post up some pics of this.
Im sure someone can spot your issue.
Perhaps Functional Artist can help with the pixie wrangling.

Side note: Perhaps we should call him Fiberglass Artist now.

Here are some photos, I have changed the rear sprocket to a smaller one but still won't move under load. I even wired it up to a large car batter but no improvement.

 

[steve13]

here are some photos, i changed the rear sprocket to a smaller size but still won't move under load, i even tried wiring it up to a car battery to see if it was lack of power in my battery set up but still doesn't work?

 

[steve13]

I would feel around for hot wires and hot connections. Resistance causes heat and hot parts will show loose, corroded or undersize wires and connections.

I have changed the wiring to a larger size.I have run the gokart and the controller,wiring and motor do not get hot? I have added extra battery in parallel I even disconnected the batteries and connected to a car batter. Gokart works until you put a small load on the wheels, doesn't even move under its own wight?

 

[Functional Artist]

i changed the rear sprocket to a smaller size but still won't move under load

Howdy
...& welcome

Probably, opposite of what you should have done.

Usually the "best" place to start when DIY figuring gear ratio, on a small vehicle is ~6:1

For example, a 10 tooth "drive" sprocket on the motor
...& a 60 tooth "driven" sprocket on the axle

What is the "current" GR?
...& what size tires are on this mini-vehicle?

 

[steve13]

Hi, I had a larger sprocket on the drive axle but that didn't work that's why I tried a smaller one just to see if it made any difference. I have tried several size wheels and that doesn't work? I'm thinking the motor i am using might be under powered for the size and weight of the gokart. It is 12v 250w what do you think?

 

[Hellion]

Hi Steve13.

I had a larger sprocket on the drive axle but that didn't work that's why I tried a smaller one just to see if it made any difference

We need the tooth count of the motor sprocket and the axle sprocket to calculate the gear ratio you have. Don't guess, count the teeth.




EDIT: count all the teeth on every sprocket you have used so far; it would be educational

 

[Functional Artist]

Hi, I had a larger sprocket on the drive axle but that didn't work that's why I tried a smaller one just to see if it made any difference. I have tried several size wheels and that doesn't work? I'm thinking the motor i am using might be under powered for the size and weight of the gokart. It is 12v 250w what do you think?

Yup, 12V 250W is for stuff like "plastic" Powers Wheels type vehicles

IMO 24V 500W is/would be about the minimum, to motivate a vehicle with a teenager to adult size person, like many scooters

Check this out
...FYI
...& for potentially pertinent info
https://www.diygokarts.com/community/threads/freedom-scooter-upgrades-modifications.46418/

 

[Hellion]

I have changed a pedal gokart for my grandson into a 12v gokart...

We would LOVE to see this electric conversion of yours. Photos speak 1,000 words and would elucidate your project so much better for all involved. You can upload them directly to the site with the image icon at the top of the reply entry box.

 

[steve13]

Hi Steve13.



We need the tooth count of the motor sprocket and the axle sprocket to calculate the gear ratio you have. Don't guess, count the teeth.




EDIT: count all the teeth on every sprocket you have used so far; it would be educational

 

[steve13]

There are 9 teeth on the motor sprocket and 24teeth on the axel sproket.

 

[Functional Artist]

There are 9 teeth on the motor sprocket and 24teeth on the axel sproket.

24/9= 2:67 GR (gear ratio)

So, yup, that right there is the biggest "factor" in your "no power under load" issue

For more info...maybe check out this thread
https://www.diygokarts.com/community/threads/simple-low-cost-electric-go-kart-conversion.37442/

 

[Hellion]

24/9= 2:67 GR (gear ratio)

In practical terms, your gear ratio means a crazy high top speed but almost zero torque. The thing won't move.

 

[panchothedog]

Putting on a smaller axle sprocket is COMPLETELY WRONG. To lower the gear ratio so that you have more torque ( power ) you need a LARGER axle sprocket.
If you have a 9 tooth on the motor, you want a 54 tooth on the axle. If one that big is not available, then the largest one you can find. You went the wrong direction when you changed too a smaller axle sprocket.

 

[Edwin Spangler]

Putting on a smaller axle sprocket is COMPLETELY WRONG. To lower the gear ratio so that you have more torque ( power ) you need a LARGER axle sprocket.
If you have a 9 tooth on the motor, you want a 54 tooth on the axle. If one that big is not available, then the largest one you can find. You went the wrong direction when you changed too a smaller axle sprocket.

There are 9 teeth on the motor sprocket and 24teeth on the axel sproket.

I understood it as making the REAR sprocket smaller, which is the drive sprocket. -Which is the way he wants to go. -Although he cannot go any further in that direction as its 9 tooth already. He now needs to have a bigger front sprocket.

-This is IF im looking at the pics correctly.