Can 36v be better than 48?

[spokewrench]

Aventon seems to be going to 36 volts. There must be advantages.
Maybe it could prevent users from getting far more than legal power with an aftermarket controller.
Maybe a 36 volt battery is easier for a controller to keep equalized.
Anyone know why Aventon is reducing voltage?

 

[RunForTheHills]

If I had to guess, 36V batteries may be easier / cheaper to source. Higher voltage has a few advantages, like lower current for the same power, but a 36V bike can be engineered to provide the same power and speed as one with a 52V battery. You are just going to need thicker wires, a controller that can handle the higher current, a faster winding on the motor, etc.

 

[harryS]

It's probably an economic thing, Less cells in a 36V pack. and if the customer accepts the lower performance, seller saves some money, Still, I think most any ebike can hit the class 1 or class 2 20 mph limit on 36V,

I have a 10 cell 36V4.2Ah battery made with Molicell P42A 21700 cells that can still put out a 30A peak current, It's about 150WH and I can squeeze out 16-18 miles out of it.

 

[spokewrench]

The Aventon 48 volt battery is 678 watt hours, while the 36 volt battery is 720 watt hours. It looks like the 36-volt battery would cost a little more.
I was thinking of back emf. A PM motor is a generator. The faster it turns, the more voltage it produces against the battery. If you hooked it to a 48 volt battery with no load on the motor, it could spin up to where the back emf was 48 volts. I wonder if 48 volt batteries came in for Class 3: 28 mph. At 36 volts, the same motor would be good for 21 mph, which in the US is just over the limit for Classes 1 and 2.

I figure to go faster than 20 or so with a 36 volt battery, maybe you'd need a different motor besides a different controller.

 

[RunForTheHills]

I figure to go faster than 20 or so with a 36 volt battery, maybe you'd need a different motor besides a different controller.

You would need a motor with a faster winding. For the same winding on a motor a higher voltage will top out at a faster speed than a lower voltage.

 

[Stefan Mikes]

Since I've been riding e-bikes, premium brands ran their systems on 36 V, now delivering even 800 Wh batteries. 48 V was introduced for low power lightweight e-bikes to make the battery slim.
It is a myth a powerful e-bike requires a high voltage (unless it is a primitive illegal monster). It is down to a proper and sophisticated design not only of the motor but also the whole system.

 

[Underdog]

I ride an Aventon 36v and a Velotric 48v bike, I can't really tell a difference in performance, and mileage is better with the 36v bike. The 36v battery is also a lighter weight battery compared to a 48v of the same size. That being said either system will serve you well.

 

[mschwett]

The Aventon 48 volt battery is 678 watt hours, while the 36 volt battery is 720 watt hours. It looks like the 36-volt battery would cost a little more.
I was thinking of back emf. A PM motor is a generator. The faster it turns, the more voltage it produces against the battery. If you hooked it to a 48 volt battery with no load on the motor, it could spin up to where the back emf was 48 volts. I wonder if 48 volt batteries came in for Class 3: 28 mph. At 36 volts, the same motor would be good for 21 mph, which in the US is just over the limit for Classes 1 and 2.

I figure to go faster than 20 or so with a 36 volt battery, maybe you'd need a different motor besides a different controller.

almost all ebike motors are geared tho, so the relationship between the motor speed and the wheel speed is whatever the motor manufacturer wants it to be. at a lower voltage you could just gear it down less and up the current for more torque at the lower speed. i am not really sure what the pros and cons would be. 10s7p at 14a vs 13s6p at 10.5a... would it really matter?

 

[DaveMatthews]

Interesting that Giant seems to be starting down the 48v path after years running 36v.

 

[fooferdoggie]

Interesting that Giant seems to be starting down the 48v path after years running 36v.

More power is typical in the world. I can't even use all the bosch power on the 4 gen motor. Even a 20% grade I only have to put out 450 watts or even less if I go up slowly. Now after riding a acustic bike, it's way more than I need. Speed is addicting.

 

[Gionnirocket]

More power is typical in the world. I can't even use all the bosch power on the 4 gen motor. Even a 20% grade I only have to put out 450 watts or even less if I go up slowly. Now after riding a acustic bike, it's way more than I need. Speed is addicting.

I see no reason an ebike has to emulate a conventional one closely. I enjoy the extra power and speed of my ebike though I typically ride in a very similar speed range. Speed is addictive but torque/acceleration is a glowing crack pipe!
That said higher voltages will typically yield better performance and efficiency, while a lower voltage battery of the same cell count will have a more stable output with a greater current capacity. Both have their advantages and it depends on your needs/wants.

 

[fooferdoggie]

I see no reason an ebike has to emulate a conventional one closely. I enjoy the extra power and speed of my ebike though I typically ride in a very similar speed range. Speed is addictive but torque/acceleration is a glowing crack pipe!
That said higher voltages will typically yield better performance and efficiency, while a lower voltage battery of the same cell count will have a more stable output with a greater current capacity. Both have their advantages and it depends on your needs/wants.

I know I can't I tried riding my Trek to get the same workout on my acoustic, and it is almost impossible even in the lowest assist level. I am not trying to work hard on the acoustic either.

 

[Gionnirocket]

I know I can't I tried riding my Trek to get the same workout on my acoustic, and it is almost impossible even in the lowest assist level. I am not trying to work hard on the acoustic either.

I have my Zen PAS 1 set so low, it feathers in 25 - 100w. You can definitely get a workout if you want one. I have the first 4 PAS set to be very subtle and each increase is just enough to make a small difference and keep you pushing.
PAS 5 - 9 and now we're talkin' crack pipe power.

 

[fooferdoggie]

I have my Zen PAS 1 set so low, it feathers in 25 - 100w. You can definitely get a workout if you want one. I have the first 4 PAS set to be very subtle and each increase is just enough to make a small difference and keep you pushing.
PAS 5 - 9 and now we're talkin' crack pipe power.

i get a workout but its not as much as I get on the acoustic without power. it just feels too easy. I am now so much faster on the tandem now too.

 

[spokewrench]

almost all ebike motors are geared tho, so the relationship between the motor speed and the wheel speed is whatever the motor manufacturer wants it to be. at a lower voltage you could just gear it down less and up the current for more torque at the lower speed. i am not really sure what the pros and cons would be. 10s7p at 14a vs 13s6p at 10.5a... would it really matter?

Of 4 e-bikes I've had, only the first had a geared motor. I think the advantage to gears is lightness because you can get torque with fewer poles. Geared or direct drive, if a motor is set up for a back emf of 48 at a little over 28 mph, a 36 volt battery won't let it spin much over 21 mph regardless of the controller.

That said, I see the Aventon has a hub-drive model that can be used as class 3 on a 36-volt battery. Hmmm... I wonder what that motor would do on 48 volts...

 

[mschwett]

Of 4 e-bikes I've had, only the first had a geared motor. I think the advantage to gears is lightness because you can get torque with fewer poles. Geared or direct drive, if a motor is set up for a back emf of 48 at a little over 28 mph, a 36 volt battery won't let it spin much over 21 mph regardless of the controller.

That said, I see the Aventon has a hub-drive model that can be used as class 3 on a 36-volt battery. Hmmm... I wonder what that motor would do on 48 volts...

hmmmm. i think pretty much every mainstream bike from aventon, gazelle, specialized, trek, giant, vanmoof, etc is a geared motor. even rad switched to geared like 5 years ago, i think.

in addition to more torque geared motors are smaller and more efficient at low speeds, because the motor isn't trying to move you along at 40rpm or something bonkers, they usually have internal clutches for reduced drag, etc. the only downsides are the whine and lack of regen.

 

[spokewrench]

hmmmm. i think pretty much every mainstream bike from aventon, gazelle, specialized, trek, giant, vanmoof, etc is a geared motor. even rad switched to geared like 5 years ago, i think.

in addition to more torque geared motors are smaller and more efficient at low speeds, because the motor isn't trying to move you along at 40rpm or something bonkers, they usually have internal clutches for reduced drag, etc. the only downsides are the whine and lack of regen.

My 2020 Radrunner had 20 poles and 5:1 gearing. I believe the Rover and the Mini used the same motor. To program a KT controller, one multiplied the poles by the gearing and said it had 100 poles. Using a motor with 100 poles would have the same effect as gearing a 20-pole motor: 5 times the torque with 1/5 the rpms.

My 2021 Evryjourney, my 2021 Radmission, and my 2023 Abound all had freewheeling direct drive. With about 5 times more poles, they weigh about twice as much as geared motors, which made the back wheels massive compared to the Radrunner. They're much quieter than the geared motor.

Manufacturers use them for durability. If it takes 3 minutes at full throttle to climb a hill, a 10 pound direct-drive motor will warm only half as much as a 5-pound geared motor. Nylon gears are popular because they are light, cheap, and quiet, but they often fail.

 

[BlackHand]

freewheeling direct drive

?? How does that work?

Maybe your definition of direct drive hub is different than what I'm used to seeing... The Radmission uses a geared hub, the current Abound uses a geared hub and I don't think a cargo eBike would make much sense with a direct drive hub.

Understanding the Differences Between Direct Drive & Geared Electric Bike Hub Motors – Electric Bike Report

Which electric bike hub motor is best for you; direct drive or geared? Find out in this guide to e-bike hub motors.

electricbikereport.com

 

[gromike]

.... I don't think a cargo eBike would make much sense with a direct drive hub.

I think a direct drive motor would make a superior cargo bike if done right. You would need to throw enough amps into the motor, and have good gearing for pedaling. It's the most reliable motor, albeit bigger and heavier. But it's a cargo bike and the extra weight of the motor and battery wouldn't be an issue. Torque sensing PAS, throttle, and regenerative braking would be sweet in any cargo bike.

 

[sc00ter]

Very interesting topic spokewrench as I'm planning a test ride on a Abound LR when I find one in stock. I watched a few videos, sponsored and free agent ones, and overall it seems equal to most 48volt hub drive cargo bikes. I have a pretty good base line with my RadRunner 2 as when my wife and I take it on short rides around the area I just use the throttle full time. The one bike shop by me said I can take her out on the back for the test ride on the Abound LR!

Tried to look at a Globe LT but all the shops (100 miles away) were sold-out. Velotric discontinued the Packer and my local shop sold their last one. The nearest Cannondale dealer with a Cargowagon on the floor is over 200 miles away and the test ride conditions are lame (parking lot only and no wife). So the Abound LR is the next logical choice. I just thought 36volts wouldn't be enough.