4x4 LSV using hub motors?

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remolacha   10 µW

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4x4 LSV using hub motors?

Post by remolacha » Jun 29 2020 4:01pm

Hi everyone. I'm a high school teacher who runs an EV program. Thus far we've made a bunch of electric bikes and done an S10 conversion. The next project is to build a small electric utility truck, to replace a Toro Workman HDX Auto, for the maintenance staff. The maintenance guys use it for low-speed, high torque tasks like pulling a sand spreader and hauling pallets of fertilizer up steep grades. Has anyone tried something like this using hub motors? I have been looking for low speed high torque motors and haven't found much in the range we would need.
We prefer hub motors for the simplicity of the build. Are we barking up the wrong tree?


Josh Merrow

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amberwolf   100 GW

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Re: 4x4 LSV using hub motors?

Post by amberwolf » Jun 29 2020 5:14pm

There are a number of low speed 4 wheel (quad) hubmotor builds here on ES, including someone's powerchair for their daughter, a cargo cart, and some other stuff, though you'll have to poke around for them as I don't have any direct links.

Some used bicycle hubmotros in small wheels, some used some of the heavier-duty scooter hubmotors, some used some of the powerchair motors, etc. Goldenmotor, UUmotor, and other places make single-ended-axle hubmotors that bolt directly to rims (rather than lacing to them) for automotive-tire use.

But I don't think they're going to have the power level you're after. You'll probably have to go to QSmotors and similar places for car-sized hubmotors...which will be designed to provide most of their power at higher speeds, though you could have them wind the motors for slower speeds and higher torque.

LeftieBiker   100 kW

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Re: 4x4 LSV using hub motors?

Post by LeftieBiker » Jun 29 2020 5:21pm

I think that if you need hub motors for 'high torque from start' use, you'll have to stick to geared motors, and you may not find any in the power range (8-10kw?) you need.

Hillhater   100 GW

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Re: 4x4 LSV using hub motors?

Post by Hillhater » Jun 29 2020 6:47pm

As this is an educational exercise, why not start from first principles to gather data and estimate the power/Torque/ energy, etc etc needed....such that you can self define the actual specification of the drive motors required.
Pick the worst case situation ..max load, maximum grade, typical speed, etc ,...and measure or calculate the tractive force needed...work on from there to establish each motor power.
It will be very worthwhile for students to learn what is involved in identifying correct equipment specifications..
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remolacha   10 µW

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Re: 4x4 LSV using hub motors?

Post by remolacha » Jul 06 2020 10:24am

Thanks everyone...Good leads and advice.


remolacha   10 µW

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Re: 4x4 LSV using hub motors?

Post by remolacha » Sep 18 2020 12:16pm

So the use case has changed a bit, now the maintenance guys want a small 2WD truck for getting material around campus. We've decided on a 72V system with 2 x QSMotor 2000W QS205 hub motors mated with 2 x Kelly KLS7230S controllers. Our design (unless we're missing something, quite possible) doesn't need a 12V battery. We borrowed this idea from the Kelly schematic (attached). We've got the DCDC converter (which powers the Dilithium BMS) connected both to the high amperage side of the contactor and charger output (so the bms is energized both while running and charging. The two diodes, we hope, insure that the battery doesn't power the DCDC when the vehicle is off and not charging. We've left off the controller-motor connections and the throttle, which seem to be pretty much plug and play.

One doubt we have is our contactor is 72V on both sides...

Would any of you kind souls mind taking a look at our schematic and giving us feedback?'

Kelly controller manual: https://www.kellycontrollers.eu/custom/ ... alV1.9.pdf

Josh, Alex & Aidan
Schematic 2.0.png
Schematic 2.0.png (100.73 KiB) Viewed 1868 times
Screen Shot 2020-09-18 at 1.02.54 PM.png
Screen Shot 2020-09-18 at 1.02.54 PM.png (390.31 KiB) Viewed 1868 times

hasp   1 mW

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Re: 4x4 LSV using hub motors?

Post by hasp » Nov 11 2020 2:07am

very interesting!

2 friends and i built a little utility car for moving equipment around film sets and occassional camera work.
the first one was not hub driven, the build is explained here: viewtopic.php?f=34&t=104174&p=1578340#p1578340

but now we are building a second one with 4x1500w qs205 hubmotors.

very curious about what you guys are gonna come up with.

Marshall2389   1 µW

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Re: 4x4 LSV using hub motors?

Post by Marshall2389 » Apr 11 2021 9:24am

Grin Technologies sells a geared wheelbarrow motor that might suit your needs; https://ebikes.ca/geared-wheelbarrow-motor.html

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everythingisawave   100 mW

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Re: 4x4 LSV using hub motors?

Post by everythingisawave » Apr 11 2021 12:30pm

Sounds like a fun project.
It is probably a good idea to have some kind of interlock to disable driving when charging is happening, as well as a maintenance plug that de-energizes the system manually. Also, moving the main fuse closer to the battery output is advisable, so that any kind of fault can be cut off.

Do the Kelly controllers have their own bleed resistor, and pre-charge circuit?

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