75 Rupp Centaur

[xXSaneXx]

I have one currently and looking into converting to electric. It weighs 720lbs stock with its 2 stroke 340cc motor, trans and tank along with a few things I'll remove to make lighter.
I'm planning on a qs180 with fardriver 72580 with a switch that will alow it to go reverse as well. The original trans is a cvt type that only has forward and reverse. It's basically a snowmobile motor with a 54t gear for highway use. It's current topspeed is 45mph.
I'm looking qt amorge batteries like a 72v50ah with high amps.
What you guys think? Fun? Lmao

 

[harrisonpatm]

Woah, had to google it. That thing looks crazy!

Can we get some goals of your top range and speed? Also, do you know rear wheel dimensions? That will help us advise you on battery and motor selection.

 

[xXSaneXx]

Woah, had to google it. That thing looks crazy!

Can we get some goals of your top range and speed? Also, do you know rear wheel dimensions? That will help us advise you on battery and motor selection.

My goal as far as speed, anything better than 45mph lol
Range I was thinking around 50-80miles as it will just be a cruiser but I'm assuming I can increase range later by adding another battery? My rear wheels are 15x7 with 195/55/15 but id like to change the wheels as it's got a atv solid axle with a center mount disc brake. It's 8ft long, 5ft wide in the rear. The gas tank is 36inch long, 10inch wide an deep. I'd like to put battery in its spot, so plenty of space going upward.
I added pictures of mine. It current has Ford bronco wheels which not a fan of. The fronts been converted to disc brake with a cbr350 front similar to a dirt bike. An rear shocks are dirt bike shocks as well.

 

[harrisonpatm]

Looks like this is halfway between a car and a motorcycle, should be a fun project!

What we usually tell people doing their first conversion project is something like this: your battery and motor choice will determine range, speed, and acceleration. Pick one to prioritize, its unlikely you'll be able to max out on all 3, especially on your first build.

45mph is a good, modest, and achievable speed range. 50-80 miles range is a little bit out there, especially with your heavier build, but still achievable. 72v nominal range is what you're looking at now, and it's going to be the most common voltage range for a build like yours, but I'd consider going up to 96v nominal. You mentioned the QS180, I think that's a good start, especially if you're keeping your top speed under 50mph. If you really want to go faster than that on a regular basis, I'd consider going up to the newer qs165 12000w, just so you'll have more wiggle room in your specs.

Someone else will have to give their specific experiences/recommendations regarding Amorge batteries, but I can tell you that you're going to be looking at an estimated efficiency of about 140-150wh/mile (this is a wild estimation, it'd be impossible to tell what your actual efficiency will be, I'm just eyeballing it. My 365-pound motorcycle gets 110wh/mile, my moped gets 40-50 wh/mile, an aerodynamic Tesla will get 200-300 wh/mile...). Meaning, if you want 80 mile range, you'll need roughly a 12kwh battery. At 72v, that's 166ah. So, your original suggestion of a 72v 50ah battery is likely to be way under spec for the range you want.

If you can go up to 96v, Fardriver makes a couple of 96v models that might work for you.

Hopefully that gets you started. This looks fun!

 

[amberwolf]

My goal as far as speed, anything better than 45mph lol
Range I was thinking around 50-80miles as it will just be a cruiser but I'm assuming I can increase range later by adding another battery? My rear wheels are 15x7 with 195/55/15 but id like to change the wheels as it's got a atv solid axle with a center mount disc brake. It's 8ft long, 5ft wide in the rear. The gas tank is 36inch long, 10inch wide an deep. I'd like to put battery in its spot, so plenty of space going upward.
I added pictures of mine. It current has Ford bronco wheels which not a fan of. The fronts been converted to disc brake with a cbr350 front similar to a dirt bike. An rear shocks are dirt bike shocks as well.

let's assume you need 50mph

a bit of googling that hopeuflly found the right info says the original 339cc engine probably made around 50hp, which would be around 37.5kw, and if it was run flat out might make 55mph.

so let's just be pessimistic and assume you're going to need 38kw to reach 50mph.

so at 50mph 50 miles range would take an hour to reach, so that would be 38kwh of battery. 80 miles range would take proprotionally more, 80/50 x 38kwh =60.8kwn. round up to 61.

if you go with 72v that'd be 61 / 72 = 84.7ah, callit 85Ah. if 96v, then 61/96, etc.

you'll have to use cells that can produce the current required for the total power you actually need (which could be higher or lower than 38kw; if you can find out the cda you can calculate it more readliy but you can measure total frontal area fora decent guesstimate and use with online calauclators for this. ).




fwiw i've actualy seen one of those in sparkly dark blue around here now and then, maybe a dozen times in the last decade or so, didn't know what it was--never seen another so thought it was custom.

 

[xXSaneXx]

let's assume you need 50mph

a bit of googling that hopeuflly found the right info says the original 339cc engine probably made around 50hp, which would be around 37.5kw, and if it was run flat out might make 55mph.

so let's just be pessimistic and assume you're going to need 38kw to reach 50mph.

so at 50mph 50 miles range would take an hour to reach, so that would be 38kwh of battery. 80 miles range would take proprotionally more, 80/50 x 38kwh =60.8kwn. round up to 61.

if you go with 72v that'd be 61 / 72 = 84.7ah, callit 85Ah. if 96v, then 61/96, etc.

you'll have to use cells that can produce the current required for the total power you actually need (which could be higher or lower than 38kw; if you can find out the cda you can calculate it more readliy but you can measure total frontal area fora decent guesstimate and use with online calauclators for this. ).




fwiw i've actualy seen one of those in sparkly dark blue around here now and then, maybe a dozen times in the last decade or so, didn't know what it was--never seen another so thought it was custom.

I already talked to someone about the qs180. He said with the fardriver nd72580 I can more than double it's 16000 watt peak power an it will be a screamer. I talk to someone who has a 700lb atv (stock weight but around 4-500lbs afterwards) that used the qs180 an with a nd721000 an he had to tune the controller down to 100amp because at the default setting at 250amp he couldn't keep front wheels on ground. Now the one I'm looking at the fardriver has 450amp and 800 amp peak which would put it close to 40k. The amorge battery I was looking at is a 72v50ah 400amp with a peak of 850amp so if the math is right. 72v x 400amp =28,800 and at peak 72v x 800amp =57,600watts. So id think a 4-500lb trike would be carried quite well

Btw these had 12hp. The one with 50hp were the ones converted to vw aircool 1600cc power. The 2 stroke 340cc had like 35lbs torque. Top speed 45 at like 5500rpms lol pretty sad hahaha!

 

[j bjork]

I dont know if it is something different, but usually fardrivers numbers means phase amps. If it is 580pA, then it is not really interesting for this motor. You should have something with over 1000pA, like a nd961800 or someting similar. And 72V is also limiting performance.

I cant say for sure, but I would be surprized if a qs165 would have better performance than qs180. The size sure tells another story.

And for battery, in something like that there should be possible to use battery modules from electric cars, if you want good quality at a good price.

 

[xXSaneXx]

I dont know if it is something different, but usually fardrivers numbers means phase amps. If it is 580pA, then it is not really interesting for this motor. You should have something with over 1000pA, like a nd961800 or someting similar. And 72V is also limiting performance.

I cant say for sure, but I would be surprized if a qs165 would have better performance than qs180. The size sure tells another story.

And for battery, in something like that there should be possible to use battery modules from electric cars, if you want good quality at a good price.

I'm not sure on battery modules for cars. There's nothing on this that's like a car, so that's where I'm confused. I'm told a qs180 on this would be good an have plenty of torque off line an at least do 80 with no problem (even though I'll never do 80 lol, it's smaller than what yall think. It's only 8 feet long.
The motor, trans an gas tank are all the weight. Remove that an now the bikes 400-500lbs. Like I said it's got a snowmobile/atv motor an suspension in rear. Idk

 

[bananu7]

Car battery packs are often split into smaller sections for use on smaller vehicles. You don't need to use the entire car-sized pack.

 

[xXSaneXx]

Car battery packs are often split into smaller sections for use on smaller vehicles. You don't need to use the entire car-sized pack.

So something like these? High Discharge 600A LiFePo4 74AH Prismatic Cells

 

[bananu7]

So something like these? High Discharge 600A LiFePo4 74AH Prismatic Cells

Nah, those are sold individually. The economical option is to look for sellers of packs from e.g. damaged packs. Cars often use large pouch cells that are combined, and then depending on the needs they either need to be split and recombined or a part of the battery can be used.

As far as chemistry goes, LiFePO4 batteries have lower energy density than regular lithium-ion cells, so they're used for applications like residential power storage instead.

 

[j bjork]

I think the motor is probably a good choice, but I'm not so sure about the rest.
It dosent matter how capable motor you have, if you dont feed it.

It takes phase amps to make torque, if your controller only is capable of 580pA you wont get very much torque.
You should have a controller capable of double that.

It takes voltage to get rpm, and to just run 72V means you loose some of that.
Voltage x line amps= power, it is important to have a battery that can deliver the amps.

You have a pretty big vehicle, so was thinking you probably have some freedom when designing a battery.
So I just suggested an alternative to ordering Chinese built.
I was thinking modules similar to this:

New 4s Sunwoda 14.68v 150ah 2.2kWh Lithium Ion - $50/kWh

Just $110 for brand new 14.68v 150ah 2.2kWh batteries. Crazy deal on these. Every battery is factory tested and perfectly balanced. Excellent energy density. You can easily add a 4s Lithium Ion BMS or series these into higher voltages. The lids just pops right off if you use a flat screw driver...

batteryhookup.com

Maybe not that one exactly, they are just 4s, so it would take 7 in series to get 28s

 

[j bjork]

It sounds like you havent bought anything yet, so this might be interesting:

New in box QS180 90H and Fardriver ND961200B direct from QSmotor

I am selling a new QS180 90H mid-drive motor and a Fardriver ND961200B motor controller. I bought these directly from QSmotor and never opened the boxes. Pictures of the items are what I was sent from QSmotor before they shipped it. The picture of the boxes is what I currently have. Asking $1000...

endless-sphere.com

With a more suitable controller, even if I personally would have went for a 961800..

 

[hugok]

It sounds like you havent bought anything yet, so this might be interesting:

New in box QS180 90H and Fardriver ND961200B direct from QSmotor

I am selling a new QS180 90H mid-drive motor and a Fardriver ND961200B motor controller. I bought these directly from QSmotor and never opened the boxes. Pictures of the items are what I was sent from QSmotor before they shipped it. The picture of the boxes is what I currently have. Asking $1000...

endless-sphere.com

With a more suitable controller, even if I personally would have went for a 961800..

I would say j bjork is right on track here. Go for the larger fardriver controllers. It's better to have a large one and not need to push it to the limit. You need to keep in mind that the rating of the fardriver controller is peak and not continues rating.

 

[xXSaneXx]

I would say j bjork is right on track here. Go for the larger fardriver controllers. It's better to have a large one and not need to push it to the limit. You need to keep in mind that the rating of the fardriver controller is peak and not continues rating.

Ok so what fardriver controller would you recommend use with the qs180? It has a higher wattage rating an has been used on quads that are in the 500-700lb range. It's a encoder motor. Hall isn't available for it.
The reason I was going with the one I said above is because a guy who builds racing gocarts that weigh the same uses the same setup an does 100mph no problem at all, which isn't my top speed goal but it's there. I will be converting it to chain drive with a 54t gear which is already on it with the belt drive setup it currently has. Also I'm going to remove alot of its weight going electric as well. It's not as huge as you guys think btw. Yall keep saying *something that huge*. Units 8ft long but the fiberglass body is only 6ft long an it's 5ft long from left to right only in the rear. I can pick the front end up myself and 2 can lift the rear up lol

 

[hugok]

I think the motor is probably a good choice, but I'm not so sure about the rest.
It dosent matter how capable motor you have, if you dont feed it.

It takes phase amps to make torque, if your controller only is capable of 580pA you wont get very much torque.
You should have a controller capable of double that.

It takes voltage to get rpm, and to just run 72V means you loose some of that.
Voltage x line amps= power, it is important to have a battery that can deliver the amps.

You have a pretty big vehicle, so was thinking you probably have some freedom when designing a battery.
So I just suggested an alternative to ordering Chinese built.
I was thinking modules similar to this:

New 4s Sunwoda 14.68v 150ah 2.2kWh Lithium Ion - $50/kWh

Just $110 for brand new 14.68v 150ah 2.2kWh batteries. Crazy deal on these. Every battery is factory tested and perfectly balanced. Excellent energy density. You can easily add a 4s Lithium Ion BMS or series these into higher voltages. The lids just pops right off if you use a flat screw driver...

batteryhookup.com

Maybe not that one exactly, they are just 4s, so it would take 7 in series to get 28s

I was actually also on my way to recommend that battery but I think 5 is enough for this build. That would be over 10 kWh and possible to deliver more power than needed.

 

[xXSaneXx]

This is a Google image but this is what's under the body. It's basically a gocart lol

 

[fechter]

Just for reference, here's one that's fully assembled. This one belonged to Elvis Presley.
I wonder what the turning radius is on one of those?

 

[xXSaneXx]

Just for reference, here's one that's fully assembled. This one belonged to Elvis Presley.
I wonder what the turning radius is on one of those?

View attachment 368179

It's pretty decent. They are small like a slingshot. The take corners pretty good . Mine has a different front end an it's been converted to disc up front. They use dirt bike front ends and dirt bike rear shocks. Fun to drive

 

[xXSaneXx]

It's pretty decent. They are small like a slingshot. The take corners pretty good . Mine has a different front end an it's been converted to disc up front. They use dirt bike front ends and dirt bike rear shocks. Fun to drive

Also that's a 74, mines a 75. The difference is that one is a 1 seater mine is a 2 seater(if you wanna call it that) lol small people lol
But I think Elvis had a vw motor in his.

 

[xXSaneXx]

Ok so after talking to a rep the nd72580 won't work with the qs180 as the motor is a encoder, an that controller is for hall.
Also I found this info for the motor I'll be purchasing.
It shows the amps. This motot works with 72v by the way. There's not alot of room for huge car batteries. That's why I'm looking at the amorge battery. Here's a list, what you think on those setups?

 

[hugok]

They are 14" x 6" x 4.5, can't fit 5 of those? Ofc you can go for Amorge but it will be like 3 times the price for 1/3 of the battery capacity.

Not sure but guess you will be charged the 35% tariff when buying from China if you don't get the stuff before before May? Might be worth paying for fast shipment.

 

[xXSaneXx]

They are 14" x 6" x 4.5, can't fit 5 of those? Ofc you can go for Amorge but it will be like 3 times the price for 1/3 of the battery capacity.

Not sure but guess you will be charged the 35% tariff when buying from China if you don't get the stuff before before May? Might be worth paying for fast shipment.

Ok, why would I need 5 of them? That's my confusion. It's no where near the size of any car. There are quads converted to electric with the same kit and battery setup that can't keep the front-end on the ground that weigh the same or more than this thing. That's the part I'm not understanding. The guy I'm talking to that builds electric motorcycles, gocarts dirtbikes ect. Says this will do 60mph easily with the range of about 50 miles. I'm not looking for 300 mile range. It's just a cruiser for short trips. Someone please explain to me why I need 5 batteries or a car battery in something that will weigh alot less than 700lbs when converted to electric please? All the weight is literally in the rear. You can lift the front yourself.

 

[StultusEst]

Ok, why would I need 5 of them? That's my confusion. It's no where near the size of any car. There are quads converted to electric with the same kit and battery setup that can't keep the front-end on the ground that weigh the same or more than this thing. That's the part I'm not understanding. The guy I'm talking to that builds electric motorcycles, gocarts dirtbikes ect. Says this will do 60mph easily with the range of about 50 miles. I'm not looking for 300 mile range. It's just a cruiser for short trips. Someone please explain to me why I need 5 batteries or a car battery in something that will weigh alot less than 700lbs when converted to electric please? All the weight is literally in the rear. You can lift the front yourself.

The batteries are 14v each so you would need multiple in series to reach 72v nominal voltage. Wiring batteries in series combines their voltage, wiring them in parallel combines their amps. I have a tiny converted CL175 with a 72v80ah battery and I get around 60ish miles of range going 45ish on average, so you'll probably want more than 50ah. Good luck with the build!

 

[xXSaneXx]

Why do I need a series of 14v to reach a 72v? Why can't I just buy a 72v50-80ah battery with Samsung cells with 300-400 bms current, with a peak of 420 to 560amps?
Id think that would be perfect as it's a battery that supports up to almost 40k watts. Volts x amps
Then with the controller 500a with peak of 1000a so it should carry that little 3 wheeler quite well in takeoff an performance for what I want. The controller I'm looking at is recommended for lightweight electric vehicles. This thing is NOT heavy lol For some reason some of you guys think I'm trying to power a car. Lol