Stock series motor ?

[70oldsracer]

Originally Posted by bobbycason

I don't see where that would be a problem personally. Mine will be mostly just riding around the yard and at campgrounds and there isn't many hills around here in SE Louisiana.

We have these for when the going gets tough lol

I have a bunch of atv's, but I wanted something electric and quiet. To be honest, I really didn't realize these carts needed so much work. Good thing I was given my cart for free.

[orangeman6]

Originally Posted by 70oldsracer

That's great! Do you do any driving in the dirt and/or up and down hills? My cart will be strictly a hunting cart. Pretty much back and forth to my hunting stands. Most of my driving will be on dirt logging roads, but I do have one pretty big incline on my property. I've included a pic of the hill, just wondering if this is going to be a problem.

Need johnnieb here for the exact numbers, but iirc, you’re going to see a ~33% increase in both speed and torque from the 36 to 48 upgrade. Your 22” tires are going to also up the speed, but also drop the torque. Johnnie has posted in a bunch of different threads about this and nails it down.

That hill doesn’t look too bad, in the pic anyway. Your other factors would be soil type to some extent, and how much weight you’re carrying. If you find you need more torque, down the road you could get a high torque motor. I know that when guys start talking about big tires and hunting buggies, the advice from the smart guys is the 48v with the other components you’ve got.

**think I’m remembering now that you haven’t actually had that cart running yet for those percentages to make any sense. However, I think stock speed is usually given as 12-14.

Hopefully johnnieb will see this soon. Guy loves him some math.

[70oldsracer]

Originally Posted by orangeman6

Need johnnieb here for the exact numbers, but iirc, you’re going to see a ~33% increase in both speed and torque from the 36 to 48 upgrade. Your 22” tires are going to also up the speed, but also drop the torque. Johnnie has posted in a bunch of different threads about this and nails it down.

That hill doesn’t look too bad, in the pic anyway. Your other factors would be soil type to some extent, and how much weight you’re carrying. If you find you need more torque, down the road you could get a high torque motor. I know that when guys start talking about big tires and hunting buggies, the advice from the smart guys is the 48v with the other components you’ve got.

**think I’m remembering now that you haven’t actually had that cart running yet for those percentages to make any sense. However, I think stock speed is usually given as 12-14.

Hopefully johnnieb will see this soon. Guy loves him some math.

Yep, cart still isn't running, but it just gives me more time to work on other things. Johnnieb said 33% from 36v-48v once before.

[bobbycason]

Originally Posted by 70oldsracer

I have a bunch of atv's, but I wanted something electric and quiet. To be honest, I really didn't realize these carts needed so much work. Good thing I was given my cart for free.

Yeah a few of the campgrounds we go to don't allow gas carts so i couldn't bring the gas club car I have.

[orangeman6]

Yeah, the 33% I’ve seen enough times to be confident enough to repeat. It’s the % torque loss with the 22” tires I don’t know about. But, like I said, you’ve got 48v, 500 amp controller, big cables, and hd f/r, which I always see prescribed for you off roaders.

[JohnnieB]

Published speed for a stock medalist with series drive is 12MPH.
Stock tire height is 18" and stock differential gears are 12.44:1.
Increasing tire height or lowering gear ratio numerically, increases speed, but reduces torque, (Technically it's the linear force applied to road rather than torque.)
Charging gears is a major undertaking, so I'll stick with tires.
Speed increase is based on tire circumference while torque loss is based on tire radius, so the percent of respective gains and losses are not equal. Attached is a chart showing the speed and torque differences for tire heights from 17" to 26".

Due to the torque loss, the cart will not reach the mathematical speed gain, but with high inflation pressure road tires, it'll be fairly close. On the other hand, low pressure (max inflation pressure <10PSI) off road tires, take more torque to turn and little, if any, speed gain will be realized. (Tires with >15PSI inflation pressure and aggressive tread patterns can be found.)

Motor heat is also tied to tire height. Increasing tire height reduces motor RPM for a given cart speed and the slower the motor turns, the more amps it can draw and the amps not converted to torque by the motor are converted into heat. The ratio of amps turned into torque vs those turned into heat is the motor's efficiency, which varies from about 50% up to about 85% depending on motor's RPM and work load. The amount of heat generated increases at the square of the number of amps being converted to heat (W = I^2 x R).

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Increasing the battery pack from 36V to 48V increases both speed and torque by 33.3%, as well as reducing amp flow by 33.3% for the same torque output.

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If they are high pressure road type, your 22" tires should up your Medalist from 12MPH to about 14.7MPH and if you went to 48V also, it should climb to about 19.6MPH. If they are off-road tires, it'll most likely be slower

[orangeman6]

Originally Posted by JohnnieB

Published speed for a stock medalist with series drive is 12MPH.
Stock tire height is 18" and stock differential gears are 12.44:1.
Increasing tire height or lowering gear ratio numerically, increases speed, but reduces torque, (Technically it's the linear force applied to road rather than torque.)
Charging gears is a major undertaking, so I'll stick with tires.
Speed increase is based on tire circumference while torque loss is based on tire radius, so the percent of respective gains and losses are not equal. Attached is a chart showing the speed and torque differences for tire heights from 17" to 26".

Due to the torque loss, the cart will not reach the mathematical speed gain, but with high inflation pressure road tires, it'll be fairly close. On the other hand, low pressure (max inflation pressure <10PSI) off road tires, take more torque to turn and little, if any, speed gain will be realized. (Tires with >15PSI inflation pressure and aggressive tread patterns can be found.)

Motor heat is also tied to tire height. Increasing tire height reduces motor RPM for a given cart speed and the slower the motor turns, the more amps it can draw and the amps not converted to torque by the motor are converted into heat. The ratio of amps turned into torque vs those turned into heat is the motor's efficiency, which varies from about 50% up to about 85% depending on motor's RPM and work load. The amount of heat generated increases at the square of the number of amps being converted to heat (W = I^2 x R).

----------
Increasing the battery pack from 36V to 48V increases both speed and torque by 33.3%, as well as reducing amp flow by 33.3% for the same torque output.

-------------
If they are high pressure road type, your 22" tires should up your Medalist from 12MPH to about 14.7MPH and if you went to 48V also, it should climb to about 19.6MPH. If they are off-road tires, it'll most likely be slower

70’s, I told you. The man is amazing with this stuff.

Johnnieb, if that chart says he’s losing 18.2 % torque with the 22” tires, do we get to directly adjust that by the 33% gain from the increased voltage? Or, is it not that simple. Apologies if the answer is above. I read it, but am not going to claim to comprehend all of it.

[70oldsracer]

I obviously put bigger/more aggressive tires on for traction and ground clearance. The problem is that I'm losing that torque I will need for climbing hills and driving through the woods. Will the upgrade to 48 volts and of the controller, solenoid,etc, etc help at all with that, or will I also need to get a new motor with more torque?

[JohnnieB]

Originally Posted by orangeman6

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Johnnieb, if that chart says he’s losing 18.2 % torque with the 22” tires, do we get to directly adjust that by the 33% gain from the increased voltage? Or, is it not that simple. Apologies if the answer is above. I read it, but am not going to claim to comprehend all of it.

The percentages don't directly add and subtract, so it isn't quite that simple.

With stock tires and gears for every 1ft/lb of torque the motor put out 16.59lbf is applied were rubber meets road.

With 22" tires and stock gears gears for every 1ft/lb of torque the motor put out 13.57lbf is applied were rubber meets road. (18.2% loss)

When the pack voltage is increased from 36V to 48V, the motor's torque increases by 1/3, so it puts out 1.33lt/lb rather than 1ft/lb and 18.09lbf is applied where rubber meets road. That is 9% more force applied than 18" tires and a 36V battery pack rather than the 15.1% difference between -18.2% and +33.3%.

[JohnnieB]

Originally Posted by 70oldsracer

I obviously put bigger/more aggressive tires on for traction and ground clearance. The problem is that I'm losing that torque I will need for climbing hills and driving through the woods. Will the upgrade to 48 volts and of the controller, solenoid,etc, etc help at all with that, or will I also need to get a new motor with more torque?

Going to 48V offsets the torque loss of the taller tires and then some, but is stock torque plus about 9% enough for what you plan on doing with cart?

My suggestion is to try it and if it isn't enough, get a more powerful motor.