# Brainstorm EV side by side



## Loganmerrell (Aug 10, 2019)

Hello everyone, this is my first post on here and I am new to the EV world so please be easy on me.

The idea: 
I need some help figuring out a design and setup for a EV side by side.
I would like to have two individual motors, one connected directly to the front differential and one to the rear. I need 4wd quite often and also like the idea that if I cook one motor I could still potentially use the other one to get home. The plan as of now is to use Polaris RZR differentials, the stock drive ratio is around 3.70:1 and there are plenty of aftermarket parts that would allow me to drop the ratio down lower.  Also I intend on using portal drive hubs that add another 4:1 gear reduction. The plan is to use 32"tires.

It would be a 4 seat design that I will build myself. So I can put a fair amount of batteries in the floor and also under the seats.

The goal is to be able to hit speeds of 50mph, have plenty of torque to get over rocks, through mud bogs and up mountains. 
The longest distance I ha e taken my current side by side is 35miles into the Alaska backcountry so I would need to be able to get out that far and return. 
Goal weight is under 2000lbs

What type of motors would I need for something like this?
How much battery capacity would I need for 60mile range?
How would I make sure that both front and rear are running at the same speed to prevent binding?

Thanks everyone 

Sent from my SM-G955U using Tapatalk


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## brian_ (Feb 7, 2017)

Loganmerrell said:


> How much battery capacity would I need for 60mile range?


The usual approach is to guess an energy consumption per mile (300 Wh/mi or more) and multiply by the desired range, but it will be hard to find a good comparison for off-road consumption.



Loganmerrell said:


> How would I make sure that both front and rear are running at the same speed to prevent binding?


With separate front and rear motors, binding of shafts (because the front and rear are connected and fight each other) is not a concern at all - it won't happen.

You do need to consider how to make the front and rear motors appropriately share the driving duties, and it would definitely be bad to have one end driving while the other is braking. The key is to keep in mind that the control of the motors should be by torque, rather than by speed. If front and rear controllers get the same desired torque signal (which could be as simple as wiring the same accelerator output to both controllers) they will drive in coordination, even though their speeds are slightly different. The challenge then becomes keeping one end from spinning the tires when it has less traction.


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## dain254 (Oct 8, 2015)

I contemplate building an electric SxS frequently... just haven't happened across a deal on a rolling chassis yet to put it to hardware. for an off road vehicle, the bind between the front/rear axles isn't as big of a deal as you would think. You have a few functional requirements defined so that is a good start - budget will be the next big consideration, that aspect will define the technologies you can afford to use!

I will always advise a beginner against using multiple motors for a first go. You will have enough trouble making a single one function with whatever battery you choose. I'd agree with Brian's 300Wh/mile or more, around 20kwh would get you the desired range. 

I've never seen any portal gearboxes that have such a dramatic ratio, they are usually less than 2:1, which most of them being ~1.33:1. for a UTV, I think a person could get solid performance out of r warp9 placed between the differentials utilizing the shafts out of the front and rear of the motor. Modern UTV boxes have 2wd/4wd select, so this will alleviate any bind concern when you are motoring around in 2wd. This is the route that I would go to build a purely off road variant.


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## rancid0076 (Aug 2, 2012)

What about a billet aftermarket rzr front diff mounted in center of sxs with motor attached were driveline input would normally be , the outputs that normally go to wheels , go to each diff instead. Would dramatically drop ratio.


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