Small electric car self build

Electric cars, trucks, ATVs, NEVs - things bigger than a motorcycle.
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hasp   100 µW

100 µW
Posts: 7
Joined: Jan 09 2020 1:11pm

Small electric car self build

Post by hasp » Jan 09 2020 4:30pm

Hi Endless Sphere,

this is my first post, i discovered this forum way too late, my first electric self build is finished by now :)

so anyways

working in grip and electrics (at the movies/TV) in a country where that business is not that much of a big industry i always envied colleagues in overseas that have golfcarts and utvs for transport and cool cameracars to mount stabilized cameras to.

like this:
Image
or this:
Image


because our industry is small we dont have trucks designated to carry polaris rangers or golf carts or anything like that around with us, i had to build something that fits into existing transport infrastructure of ours.
so if i wanted to carry less and drive more (and have the ability to mount stabilized cameras to my creation) and also be able to take it with me in existing transpo infrastructure, it had to be:
.)no wider than 80cm
.)no longer than 200cm (in order to fit a standard taillift)
.)no higher than 60cm (in order to fit into my estate car as well)
.)not too heavy (because lighting trucks surely dont have unlimited payload)

i must admit layout-wise i drew quite a bit of inspiration from classic taylor dunn carts (which i only knew from the interwebs):
Image

but mine had to be roughly half the size of that.


a friend of mine whose a mechatronic engineer had an old electric motor lying around that he offered to give to the cause and also offered to help and another friend of mine whose an all around engineering/fabrication wunderkind also offered to help.

so we got cracking.

i knew i wanted a diff, because otherwise driving corners with heavy loads on conrete surfaces would be a pain.
i soon found a tecumseh lawn mower axle that was cheap and would still in pruduction if i ever needed spares.
so we cut the quad axle i bought in china (together with all the tires and the front suspension assembly) and cut the lawn mover axle:

Image
Image
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and then joined them to one 80cm wide axle with differential:
Image
Image
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then i started welding the rear swing arm, with my trusty 300euro flux core welder :)
Image

and then ballparked dimensions:
Image

ballparked gearbox and motor positions:
Image

the gearbox also is a tecumseh lawnmover unit. costs like 80euros brandnew, is rated to withstand 15 horsepower (11kw), just like the diff.
it has 3 forward and one reverse gear (that proved useful later when using a wound field motor :)
one downside is that it is all straight geared, which males it a bit noisy.


the motor used to drive a hydraulic pump in a forklift. it is a brushed 80v 3000w unit.
sadly the output shaft was a bit shy:

Image

so my friend threw this awesome thing together:
Image

and the other one designed this:
Image

after some more welding:
Image
Image

because of our cabover design, the steering would be the wrong way round, so one of my friends designed this:
Image

and had it milled it at another friends place (the gears are off the shelf parts):
Image

steering box (aliexpress utv steering box):
Image

motor mount:
Image
we go from engine to gearbox via toothed belt (because chains dont like to lie down and the gearbox has a vertical input shaft at the bottom) and then via chain from gearbox to diff/rear axle


after more welding:
Image
after some more welding gases:
Image

primed chassis:
Image
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test assembly:
Image

finished, battery pack, 4x12V 50Ah AGM
Image

the speed controller is a aliexpress 3000w pmw controller that cost 80buck, including a gas pedal, works fine so far.
finished wiring:
Image
the LightRider has a 48v 10A charger built in



...and a bluetooth receiver and speaker:
Image


as it has 48,3mm speedrail clamps built in, the finished product is rather modular,
here as an equipment Hauler:
Image

or here as a moving platform for a stabilized camera:
Image

oh, and the steering collumn is foldable, and then it does even fit in my car:
Image

oh and heres a video:
https://www.instagram.com/p/B339pYRgxPT/



i hope you liked my lenghty post,
if you have questions or critique, hit me ! :)




something i dont know much about is li-ion batterypacks, and i am a little afraid of them.
but my next project is gonna be a self built scooter with 2 hub motors and i wanna go li-ion on that one, so please expect lots of stupid questions from me.

(googling aliexpress battery pack experiences brought me here)

:)))

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amberwolf   100 GW

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Re: Small electric car self build

Post by amberwolf » Jan 09 2020 5:03pm

kinda awesome "little" build; i like scratchbuilt stuff like this. :)

been thiking about a diff and middrive to replace the heavy hubmotors in my sb cruiser trike, so future reports of reliability of the diff and gearbox youre uisng would be very helpful, along with loading / etc info.



batteries there's more info here on es than you will ever have time to read ;) so you can probably find anything you need to know here somewhere, once you know what questiosn to ask...thats the hard part. first place i'd look is in build threads for stuff that is similar to what you want to build, so you can see what they used and how well it worked (or didn't) for them.

hasp   100 µW

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Posts: 7
Joined: Jan 09 2020 1:11pm

Re: Small electric car self build

Post by hasp » Jan 09 2020 5:05pm

hi amberwolf

well, the diff and gearbox are holding up fine so far. no problems whatsoever. all that stuff is rated to withstand 15hp (11kw)

but, as i wrote, the gearbox with its straigh cut teeth is on the noisy side (it comes from a lawnmover so i guess thats not a problem there)

but if you have electric reverse id do it without the gearbox. i wanted it because the thingy should be able to go fast with little load, like just a camera or be able to go real steep with 200kg of load, so with that range of application, 3 different gears are good. but if the ground is even i always use the highest gear, no matter the load.

if your payload is always the same (1 person) then id do direct drive and get the gearing right for your weight and purposes.


fyi, thats the gearbox:
https://www.ebay.de/itm/Peerless-Getrie ... 2815911288

thats the axle:
https://www.ebay.de/itm/Peerless-Differ ... 2822309667

and thats a unit thats both a diff and a gearbox:
https://www.ebay.de/itm/113666789653

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amberwolf   100 GW

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Re: Small electric car self build

Post by amberwolf » Jan 09 2020 5:15pm

hasp wrote:
Jan 09 2020 4:43pm
well, the diff and gearbox are holding up fine so far. no problems whatsoever. all that stuff is rated to withstand 15hp (11kw)
yeah, but power can be high speed and low torque, or low speed and high torque, or anything in between. ;)

i need the low speed high torque, so i can get started from a stop with hundreds of pounds, up to half a ton with unsuually heavy loads, very quickly reaching 20mph in less than a few seconds. dont' need more than 20mph really, but need torque to not break the drvetrain. ;)

presently i only have around 3-4kw at startup, but it's not enough torque especialy for the weight the pair of dd hubs adds. it does make it simpler and theoreticlaly more reliable, less stuff to break, which is very important...but it is heavy and has other disadvantages. not very efficient at the times i actually need that power so it decreases my range from what it could be for the same battery weight, or rather mkes me have to carrya a bigger battry to get that range.

but, as i wrote, the gearbox with its straigh cut teeth is on the noisy side (it comes from a lawnmover so i guess thats not a problem there)
don't really care about the noise that much, if i had to i oculd sounddampen it with a box around it with absorbing material. silence is better, but reliability and cost are more important....

if your payload is always the same (1 person) then id do direct drive and get the gearing right for your weight and purposes.
i'ts usually teh same, around 500lbs total me and trike, but add 50-100lbs ish for grocerty trips, and 120-150lbs when carrying one of the dogs, or 300lbs if carrying one in the trike and another on the trailer. very very rarely some multi-hundred pound load on the trailer.

i definitely appreciate the links, and added them to my watchlist for future versions of the trike drivetrain. :)

Hillhater   100 GW

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Re: Small electric car self build

Post by Hillhater » Jan 09 2020 5:27pm

Hasp..welcome to the forum.
Nice project, and cleverly executed.
One irrelevent question....
I understand the need to comply with road regs etc, but i dont see why it had to be restricted to fit in your car ?
Are trailers not available ? You would have had much fewer design restrictions if you were able to simply tow it on a trailer ?.. rather than fit INSIDE your car.
This forum owes its existence to Justin of ebikes.ca

hasp   100 µW

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Posts: 7
Joined: Jan 09 2020 1:11pm

Re: Small electric car self build

Post by hasp » Jan 10 2020 7:06am

hi hillhater,
thanks for the welcome :)

well when we are working on a shoot we are travelling with trucks that have shelves on both sides, so it has to fit inbetween, like seen here:

https://www.instagram.com/p/B339pYRgxPT/

thats what i meant by "suiting given transport infrastructure"

it is just when loading or unlading a project at a rental house that i transport it there with my car. the car doesnt come with me on shoots.


.. i hope that makes sense and i could answer your question :)

Hillhater   100 GW

100 GW
Posts: 10391
Joined: Aug 03 2010 10:33pm
Location: Sydney ..(Hilly part !) .. Australia/ Down under !

Re: Small electric car self build

Post by Hillhater » Jan 10 2020 7:14am

Ahh !, OK now i understand.
Thanks. :bigthumb:
This forum owes its existence to Justin of ebikes.ca

hasp   100 µW

100 µW
Posts: 7
Joined: Jan 09 2020 1:11pm

Re: Small electric car self build

Post by hasp » Jan 10 2020 7:18am

amberwolf wrote:
Jan 09 2020 5:15pm
hasp wrote:
Jan 09 2020 4:43pm
well, the diff and gearbox are holding up fine so far. no problems whatsoever. all that stuff is rated to withstand 15hp (11kw)
yeah, but power can be high speed and low torque, or low speed and high torque, or anything in between. ;)

i need the low speed high torque, so i can get started from a stop with hundreds of pounds, up to half a ton with unsuually heavy loads, very quickly reaching 20mph in less than a few seconds. dont' need more than 20mph really, but need torque to not break the drvetrain. ;)

presently i only have around 3-4kw at startup, but it's not enough torque especialy for the weight the pair of dd hubs adds. it does make it simpler and theoreticlaly more reliable, less stuff to break, which is very important...but it is heavy and has other disadvantages. not very efficient at the times i actually need that power so it decreases my range from what it could be for the same battery weight, or rather mkes me have to carrya a bigger battry to get that range.

but, as i wrote, the gearbox with its straigh cut teeth is on the noisy side (it comes from a lawnmover so i guess thats not a problem there)
don't really care about the noise that much, if i had to i oculd sounddampen it with a box around it with absorbing material. silence is better, but reliability and cost are more important....

if your payload is always the same (1 person) then id do direct drive and get the gearing right for your weight and purposes.
i'ts usually teh same, around 500lbs total me and trike, but add 50-100lbs ish for grocerty trips, and 120-150lbs when carrying one of the dogs, or 300lbs if carrying one in the trike and another on the trailer. very very rarely some multi-hundred pound load on the trailer.

i definitely appreciate the links, and added them to my watchlist for future versions of the trike drivetrain. :)
glad you like the links, be sure to let me know when building something with those !!!

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