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  #1  
Old 07-18-2019, 10:35 PM
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Default 4x4 electric go kart tips

Hello!
I really want to build an electric full suspension 4x4 go kart.
I want to use hub motors so that I do not have to deal with any axles or mounting motors. Does anybody have any advice, or problems I might run into?
Thanks!
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Old 07-19-2019, 12:34 AM
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Originally Posted by rexmatt View Post
Hello!
I really want to build an electric full suspension 4x4 go kart.
I want to use hub motors so that I do not have to deal with any axles or mounting motors. Does anybody have any advice, or problems I might run into?
Thanks!
Welcome! There aren't too many electric guys on the forum, but the ones that are here are good and will probably weigh in on your project soon
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  #3  
Old 07-19-2019, 08:51 AM
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Hope you have a bunch of money... that wont be cheap at all......
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Old 07-19-2019, 09:20 AM
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Hope you know how to differentially control the motors,
since otherwise driving anything but straight on paved roads will be a huge pain in the rearwheels.
Or you need to find freewheeling hub motors

Frankly, mounting one or two motors and connecting differential axles is far less complex.

'sid
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Old 07-20-2019, 11:30 PM
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Originally Posted by itsid View Post
Hope you know how to differentially control the motors,
since otherwise driving anything but straight on paved roads will be a huge pain in the rearwheels.
'sid
Haha! I am using a different esc for each motor, is that what you mean?

---------- Post added at 12:26 AM ---------- Previous post was at 12:24 AM ----------

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Originally Posted by mckutzy View Post
Hope you have a bunch of money... that wont be cheap at all......
Sadly it won’t, but on the bright side, I found a SUPER cheap supply of 30Q 18650 cells, I’m 14 and I have been saving up job money for a few years now.

---------- Post added at 12:30 AM ---------- Previous post was at 12:26 AM ----------

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Welcome! There aren't too many electric guys on the forum, but the ones that are here are good and will probably weigh in on your project soon
All you darn petrolheads !! Haha!
I’m a fan of the torque and silence of electric vehicles, but range and batteries certainly are downsides.
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Old 07-21-2019, 09:02 AM
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No, individual controllers per motor is NOT what I meant.

differential driving is spinning the outer wheel faster than the inner wheel when you go around a corner.
(longer path to cover)

And that can only be done with a differential mechanically
or electronically..
electronically it's a HUUUGE pain in the behind, since you need to alter the throttle signal
if using individual controllers or a controller that's capable of differential driving two motors
(two such controllers one for the front one for the rear wheels in your case)

and frankly a (mechanical) differential is a far easier approach.

Also:
Sources for SUPER cheap 18650 are almost always scam!
just head over to yt and search for "fake 18650"
Those fake cells are everywhere, do NOT waste money on such!

Don't waste money on used cells fom allegedly previous laptop packs.
that is in fact a thing, but it's also often used to lure you in on ebay auctions or such.

'sid
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Old 07-21-2019, 11:42 AM
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Every time I hear of some kid making batt packs with those laptop cells, all I think of is this....

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Old 07-21-2019, 03:31 PM
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Originally Posted by mckutzy View Post
Every time I hear of some kid making batt packs with those laptop cells, all I think of is this....

I think EV cells are the way to go. Premade, controlled, monitored and safe.
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Old 07-21-2019, 06:53 PM
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We've had a few guys here making the batt packs, and its great in all about the DIY and recycling aspect... but really when it comes down to it.....
A backwards battery in a set, a forgetting of a series or paralleled connection... Itll light up real good.....It is power ON from the get go....
Oh and good luck putting out a lithium batt fire.....

At least it wont go boom while Im building a gas tank, even before the fuel has been opened from the gas can to fill it...
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Old 07-21-2019, 11:29 PM
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Quote:
Originally Posted by itsid View Post
No, individual controllers per motor is NOT what I meant.

differential driving is spinning the outer wheel faster than the inner wheel when you go around a corner.
(longer path to cover)

And that can only be done with a differential mechanically
or electronically..
electronically it's a HUUUGE pain in the behind, since you need to alter the throttle signal
if using individual controllers or a controller that's capable of differential driving two motors
(two such controllers one for the front one for the rear wheels in your case)

and frankly a (mechanical) differential is a far easier approach.

Also:
Sources for SUPER cheap 18650 are almost always scam!
just head over to yt and search for "fake 18650"
Those fake cells are everywhere, do NOT waste money on such!

Don't waste money on used cells fom allegedly previous laptop packs.
that is in fact a thing, but it's also often used to lure you in on ebay auctions or such.

'sid
The speed controllers will use Hall effect sensors to change the rpm going to the motors, I think that will act as a differential per say. If not, do you have any recommendations on differentials I can use?
The original price for the cells was a normal price but I was able to negotiate to a good deal. They sent me a sample, and the capacity checks out (as fakes typically do) so I bought a load tester to test temp. under load. I’ve heard this is a pretty concrete way to spot a fake.

---------- Post added at 12:19 AM ---------- Previous post was at 12:16 AM ----------

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Originally Posted by mckutzy View Post
Every time I hear of some kid making batt packs with those laptop cells, all I think of is this....

Haha! I have done loads of research and have read tons and tons of safety information to avoid any accidents. Just got a spot welder.

---------- Post added at 12:24 AM ---------- Previous post was at 12:19 AM ----------

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Originally Posted by Tpdingo View Post
I think EV cells are the way to go. Premade, controlled, monitored and safe.
Probably, although I’m a bit of a DIY person and like to build things myself so I know how they work and can diagnose problems, also if I build my own I have flexibility to build it to the dimensions I need and can have it meet my electrical specifications.

---------- Post added at 12:29 AM ---------- Previous post was at 12:24 AM ----------

Quote:
Originally Posted by mckutzy View Post
We've had a few guys here making the batt packs, and its great in all about the DIY and recycling aspect... but really when it comes down to it.....
A backwards battery in a set, a forgetting of a series or paralleled connection... Itll light up real good.....It is power ON from the get go....
Oh and good luck putting out a lithium batt fire.....

At least it wont go boom while Im building a gas tank, even before the fuel has been opened from the gas can to fill it...
“If you are not willing to risk the unusual, you will have to settle for the ordinary” - Jim Rohn
It is definitely a risk, I am kind of obsessed with electric vehicles and their mechanics, and I really believe that even at this point the advantages/disadvantages out weigh the advantages/disadvantages of gas vehicles.

Last edited by rexmatt; 07-21-2019 at 11:32 PM. Reason: Forgot to cite quote author
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  #11  
Old 07-22-2019, 07:33 AM
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Originally Posted by rexmatt View Post
I am kind of obsessed with electric vehicles and their mechanics, and I really believe that even at this point the advantages/disadvantages out weigh the advantages/disadvantages of gas vehicles.
Me too.

Yours looks like a very ambitious project

IMO

Hub motors:
From what I understand, most hub motors cannot handle a lot of "dynamic loading"
The hard turns, power slides etc. that a kart can apply to a wheel (hub motor) is very hard on the hub
(in this case the structure of the motor)
…& also the bearings too

Multiple motors:
(as Sid said) Synchronizing & controlling multiple motors to work together, properly, isn't easy

Lithium batteries:
When working with lithium batteries, there are many factor that MUST be kept in mind. (over charging, over discharging, the individual cell balance etc.)
…that's NOT including any DIY issues that may appear (wrong cell orientation, fuses, temp sensors, welding the cells & connectors together etc.)
…& also (MOST IMPORTANT) keep in mind that if something "went wrong" most folks cannot extinguish a lithium fire or "out gassing"

Just gotta stand back & let it go
…& hopefully it doesn't take your house/garage with it)

I am not trying to discourage your project
...just keep these factors in mind
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Old 07-22-2019, 07:59 AM
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Quote:
Originally Posted by rexmatt View Post
The speed controllers will use Hall effect sensors to change the rpm going to the motors, I think that will act as a differential per say.
You think wrong!

the he sensoring is in fact workign against you,
since the controller tries to keep the speed (sometimes the current) per throttle signal a constant
(within the capabilities)

And that's the exact opposite of what you need!

No I do NOT know a controller that does that for you,
since you will also need some type of sensoring to tell the controller you are going round a corner and not in a straight line

If you need an accelerometer or a simple voltage dividing slide pot on the steering or a combination IDK, that'd be a matter of testing.

And that'd also require some in depth knowledge about reading and processing sensor data on your behalf.

mechanically a peerless 100 can take one input and gently spread that over two wheels for cheap..

'sid
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Old 07-22-2019, 09:20 AM
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Originally Posted by Functional Artist View Post
Me too.

Yours looks like a very ambitious project

IMO

Hub motors:
From what I understand, most hub motors cannot handle a lot of "dynamic loading"
The hard turns, power slides etc. that a kart can apply to a wheel (hub motor) is very hard on the hub
(in this case the structure of the motor)
…& also the bearings too

Multiple motors:
(as Sid said) Synchronizing & controlling multiple motors to work together, properly, isn't easy

Lithium batteries:
When working with lithium batteries, there are many factor that MUST be kept in mind. (over charging, over discharging, the individual cell balance etc.)
…that's NOT including any DIY issues that may appear (wrong cell orientation, fuses, temp sensors, welding the cells & connectors together etc.)
…& also (MOST IMPORTANT) keep in mind that if something "went wrong" most folks cannot extinguish a lithium fire or "out gassing"

Just gotta stand back & let it go
…& hopefully it doesn't take your house/garage with it)

I am not trying to discourage your project
...just keep these factors in mind
I am a very cautious person and I am defiantly going to take every safety precaution I can. I really appreciate your help! In no way do I feel that you are discouraging me, I asked for advice, and I got it! Thanks!

---------- Post added at 10:20 AM ---------- Previous post was at 10:14 AM ----------

Quote:
Originally Posted by itsid View Post
You think wrong!

the he sensoring is in fact workign against you,
since the controller tries to keep the speed (sometimes the current) per throttle signal a constant
(within the capabilities)

And that's the exact opposite of what you need!

No I do NOT know a controller that does that for you,
since you will also need some type of sensoring to tell the controller you are going round a corner and not in a straight line

If you need an accelerometer or a simple voltage dividing slide pot on the steering or a combination IDK, that'd be a matter of testing.

And that'd also require some in depth knowledge about reading and processing sensor data on your behalf.

mechanically a peerless 100 can take one input and gently spread that over two wheels for cheap..

'sid
Ah, ok. Do you know of a mechanical differential that I can use?
The reason I assumed that it would work is because of this go kart called the “swincar” that uses 4x4 hub motors, and this really cool suspension system. I would love to learn how they overcame the problems that you have presented to me, but there really isn’t much information about it online.
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Old 07-22-2019, 12:15 PM
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Im asuming so as the thing sells for 10K+.....
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Old 07-22-2019, 12:35 PM
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Originally Posted by rexmatt View Post
Ah, ok. Do you know of a mechanical differential that I can use?
The reason I assumed that it would work is because of this go kart called the “swincar” ...
You got me wrong,
I'm not saying it cannot work;
of course it can!
Just not with off the shelf parts!

The developement of the swincar took for all I know 5++ years
and I'm assuming differential control for individual wheels was at least one of the reasons it's years not months

mechanical, yes.. I just named it in the post you were quoting
"peerless 100"

A sodacan in size roughly.. just cut the axles and add U-joints for individual suspension.

'sid
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Old 07-22-2019, 04:55 PM
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Quote:
Originally Posted by mckutzy View Post
Im asuming so as the thing sells for 10K+.....
The Swincar? It is pretty expensive!

---------- Post added at 05:55 PM ---------- Previous post was at 05:52 PM ----------

Quote:
Originally Posted by itsid View Post
You got me wrong,
I'm not saying it cannot work;
of course it can!
Just not with off the shelf parts!

The developement of the swincar took for all I know 5++ years
and I'm assuming differential control for individual wheels was at least one of the reasons it's years not months

mechanical, yes.. I just named it in the post you were quoting
"peerless 100"

A sodacan in size roughly.. just cut the axles and add U-joints for individual suspension.

'sid
Aha, I was wondering what you were saying when you said “peerless 100”.
Seems great, Thanks!
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