Converting Polaris Ranger - Question on controller & Voltage

[Lorax_UK]

I am mid way into converting a Polaris Ranger (400 Petrol) to EV.

The plan is/was to use a QS180 motor and Fardriver 96850 controller, which I have already purchased. I got these at a good price.

The problem is that I was hoping to use a 48V battery pack, which I've designed to be modular, so I can use it for a number of different applications. But I see in the controller spec, that it's rated for a nominal battery voltage of 60-96v.
The battery I've built is just over 300Ah, and so at 1C can discharge at 300 Amps. I guess this gives me about 15kW? The motor is rated at 8kW continuous, and 15kW peak, though probably not at an under-rated 48V.

So the ideas I'm considering, are:
1- Just try the controller with 48V and see what happens
2- Buy a similar controller that's rated to run with 48V
(presumably this means I'll not be getting max performance from the QS180 motor, but this probably isn't a huge deal for me)
3- Build a battery specifically for this application, using NMC prismatic cells, about 120Ah, 96V

Do you have any advice? Thanks in advance

 

[dominik h]

What about splitting your cells in two 48V 150Ah batteries, if this is possible. So you could use them i series for the polaris and in parallel for other things.

 

[Lorax_UK]

Thank you, that's certainly a valid idea.
I'm not sure I have the expertise needed to know whether it would work for me.
So far I've used JK BMS units with battery builds, which seem to do a good job of keeping cells balanced and protected. But I'm not sure if these would be happy running in series?
Also, I've been using 304Ah lifepo4 cells, which are quite content at a 1C discharge rate, giving 300 or so amps. But if I were using 150Ah cells, I think I'd need to switch to a different cell chemistry (NMC?) to get the discharge rate I'd ideally like.

I see you're using a Li-NMC battery. Was the discharge rate factor why you went this direction?

 

[dominik h]

If you have double the voltage you will have only half the current for your desired power level.
48x300=96x150

If you already have the 304Ah cells, I would start with them. Estimated power will be half of what others get with the QS180 and you will also get only 3/4 to half of their rpm.

8C continous (800A for my 21S100Ah battery) and the cells where for free.
That is why I have installed such a big and heavy battery. I also had to lenghten the wheelbase for my battery.
The scooter was originally equipped with 24 Lifepo4 60Ah cells. But the BMS was crap and the most of this scooters survived only one or two winters without driving and charging for 3-4 months.
If I would build again I would install two 12S2P VW MEB batteries. Having 75% more energy available with 10kg reduced weight.

 

[Lorax_UK]

Thanks for your help.
I see what you mean with the higher voltage battery needing fewer amps for any given power output.

Do you have any idea if the Fardriver controller I have (96850) will even run from a 48V battery?
I guess I just need to finishing building this battery and hook it up, see what happens.

 

[amberwolf]

If the controller has an LVC, you could see if it can change down as far as your pack will be when empty.

If not, it'll require a higher voltage battery, above the controller's LVC.

 

[Lorax_UK]

Cheers
I'll give it a try and see how I get on

 

[dominik h]

You can just try it with a normal DC power supply,.
You can also spin the motor with a power supply, as long as you do not turn on regen.

 

[Bush mechanic]

Hey @Lorax_UK I hope you’re making progress, can I ask do you plan to keep the original gearbox and run the motor through that? I’m in the very early stages of scoping ideas but am hoping to convert my Ranger crew 900 to electric. I also intend to use a modular battery, as my Ranger only gets used intermittently. Would be great to hear how you have found the motor and controller .

 

[jkrienert]

What about splitting your cells in two 48V 150Ah batteries, if this is possible. So you could use them i series for the Polaris and in parallel for other things.

If you did this, you might be able to refill your paralleled pack quicker (relative to in series) with a higher amperage (comparatively lower volt) charger.

 

[harrisonpatm]

If you did this, you might be able to refill your paralleled pack quicker (relative to in series) with a higher amperage (comparatively lower volt) charger.

Not necessarily. Watts are watts. A 58.8v charger (14s times 4.2v per cell) that delivers 10 amps is a 588w charger. A 117.6v charger (28s times 4.2v per cell) that delivers half the amperage of 5 amps, is still a 588w charger. It would take the same amount of time to charge the same hypothetical battery, paralleled or seriesed.

However, the option of charging the packs in parallel has a different advantage: lower voltage chargers are cheaper. Perhaps because higher voltage systems are less common, therefore there's less equipment out there once you get over 100v, so the demand is less, price is higher.

I was curious myself and just did a quick Aliexpress search. I found a 117.6v charger, that can deliver 7 amps (we'll have to assume the rating is accurate, which you shouldn't) for $104.90, that's 825 watts. I found a similar model of charger, 58.8v, delivering 8A, for $41. That's 470 watts. Higher voltage is $0.13/watt, lower voltage is $0.9/watt. 30% cheaper. It might be worth splitting packs to 14s for charging for that reason alone. Just depends on your specific situation.

 

[dominik h]

You can buy a used huawei r4850g2, which can be used as a highly efficient 3kW Charger up to 60A.
You get them for 100 but you need to have someone who can set the output voltage via can-bus for you , if you can't do it yourself.

 

[jkrienert]

lower voltage chargers are cheaper.

...That is what I was getting at. You helped my wording get to the point. Thank you

There are some great HVC based (no CAN) chargers out there from surplus. Some of which can do ~48v and 20a +

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[jonescg]

Myself and @Easty_au are doing a lithium upgrade on one of these. Hope to get that done by mid-July.

 

[Easty_au]

Myself and @Easty_au are doing a lithium upgrade on one of these. Hope to get that done by mid-July.

Hopefully, it’s still at Polaris in midvale getting the cv’s etc changed out atm.. then need to strip old batteries and give chassis a birthday

 

[Lorax_UK]

Hey @Lorax_UK I hope you’re making progress, can I ask do you plan to keep the original gearbox and run the motor through that? I’m in the very early stages of scoping ideas but am hoping to convert my Ranger crew 900 to electric. I also intend to use a modular battery, as my Ranger only gets used intermittently. Would be great to hear how you have found the motor and controller .

Hi, yes making great progress!
I'm not sure if your 900 is the same as my 400, but I found the vehicle perfectly suited to conversion. I removed the engine and CVT unit, and kept the transfer box. So I'm left with a single splined input shaft, that powers all 4 wheels.

I've retained the gear change lever in the cab, and the transfer box still has high ratio, low ratio, park and reverse functions.
The spline on the transfer box was an odd size, but eventually I found a sprocket that fit. The Motor (QS180) I bought came with a 428 size sprocket, but I was keen to upgrade it to a 520. I was also ideally looking for a 30mph top speed in high ratio.
I measured out a distance of 5 metres on the ground, put the vehicle in high ratio and while someone slowly pushed the vehicle along, I counted the revolutions of the input shaft. Then repeated for low ratio.

I calculate that in high ratio, each rotation of the input shaft propels the vehicle 161mm, and in low ratio it's 86mm.
The motor has a top speed of 4000rpm
at 30mph in high ratio the input shaft needs to spin at about 5000rpm

I found sprockets that just about achieve this:
JTF327 for the motor
JFT3222 for the transfer box
Give me a theoretical top speed of 33mph in high and 18mph in low. Perfect!

In the end I opted for NMC cells rather than the Lifepo4 cells I'm used to using. The 114Ah NMC cells I've got, can discharge at 3C for 30 seconds, which should suit me just fine in terms of getting up hills, or getting a big trailer moving. But the proof will be in the pudding I guess!
I'm building a double decker battery pack, 12 cells on the lower level, and another 12 above. Giving me about 10kWh capacity, and a cell weight of about 43kg.
1C discharge is 114A at 89V, so 10kW (Motor is 8kW cont)
3C discharge is 342A at 89V, so 30kW (Motor is 22kW peak)

This week I got the motor mounted in the chassis, and it lines up beautifully, and feel rock solid.
I have started building the battery, and optimistically hope to be finished with that in a week.
I'm running a JK BMS (B2A24S20P)

I am yet to connect power to the motor/controller, but I'll post on here when I do.

Wishing you the best of luck with your project

 

[Lorax_UK]

For the motor mount, I laser cut some aluminium plates, tapped some holes, and created a kind of cradle for the motor to sit in,
Then used some aluminium angle, with slots in (to allow the motor to slide, and apply chain tension). These angle pieces are long enough to span 2 major chassis members. I lined this up, and drilled the chassis, then added rivnuts, before bolting the assembly to the chassis. The sprocket lines up well, and it feel solid.

 

[Easty_au]

keen to see more of this build, doing great.

 

[Bush mechanic]

Hi, yes making great progress!
I'm not sure if your 900 is the same as my 400, but I found the vehicle perfectly suited to conversion. I removed the engine and CVT unit, and kept the transfer box. So I'm left with a single splined input shaft, that powers all 4 wheels.

Wow mate that is awesome, very impressive work, and thanks for the detailed reply! I think all the Polaris ATV and UTVs use more or less the same principle of motor->CVT->transfer case, just bigger components. That is basically what I have too (just realised I said gearbox in my first post, I should have said transfer case).

I'll also aim for a top speed of 30mph (50kmh) on flat ground, I don't know what the 400 is like but the 900 feels awful even at that speed, and for my application which is just puttering around with the kids I rarely exceed even 20mph. I do have some pretty steep areas through so my starting point will be to choose a motor and sprocket ratio that can deliver good climbing torque.

Your motor mount looks very tidy, and it sounds like your have a very solid Battery. 3C really shouldn't stress those cells a great deal. keep up the good work and keep us updated with your progress!

 

[Lorax_UK]

Progress has slowed a bit, but thought I'd post a photo of the first phase of battery build.
The design I've come up with is a double-decker idea, with 12 cells on the lower layer, and another 12 on top.
Layering the cells like this works well with the dimensions I have available for the battery.
This gives the max 24 cells that my BMS can handle, and gives nominal voltage of about 90v. About 100v when fully charged.