John in CR
100 TW
Balmorhea said:
Who can find the one correct statement quoted above? It's time for the mods to start squashing this windings nonsense that has suddenly grown so prevalent again on the forum.
How practical is 72v (or 60v) for a street legal direct drive set-up meant for climbing and sub 28 mph speed?
- Thread starter ebike4healthandfitness
- Start date
Who can find the one correct statement quoted above? It's time for the mods to start squashing this windings nonsense that has suddenly grown so prevalent again on the forum.
markz
100 TW
A) I would much rather have larger diameter winding wire that is shorter which means less resistance but it can take more power which means low turn count motors (3T, 4T etc)
B) then a motor with thinner diameter winding wire that is longer which means more resistance can cant take as much power which means high turn count motors (8T etc)
Then there is copper fill.
This is a good excel calculator from Teslanv
https://endless-sphere.com/forums/viewtopic.php?f=31&t=99505&p=1457521&hilit=mxus#p1457521
More good info, but do look at the overheat written content below the vids.
https://endless-sphere.com/forums/viewtopic.php?f=2&t=92101&hilit=mxus#p1345068
For big mxus 3kw motor.
B) then a motor with thinner diameter winding wire that is longer which means more resistance can cant take as much power which means high turn count motors (8T etc)
Then there is copper fill.
This is a good excel calculator from Teslanv
https://endless-sphere.com/forums/viewtopic.php?f=31&t=99505&p=1457521&hilit=mxus#p1457521
More good info, but do look at the overheat written content below the vids.
https://endless-sphere.com/forums/viewtopic.php?f=2&t=92101&hilit=mxus#p1345068
For big mxus 3kw motor.
MadRhino
100 GW
John in CR said:
+1
This had been solved long ago, but still misunderstood.
Think what you misunderstand is that not everyone wants to ride like a motorcycle, and motorcycle setup doesn't help us.
The OP wants 750W and 20mph, but he for some reason wants to use 72V to do that. I think it's a bad idea, the same way it's a bad idea for John in CR to prescribe a 3 turn motor to do the same thing.
The OP wants 750W and 20mph, but he for some reason wants to use 72V to do that. I think it's a bad idea, the same way it's a bad idea for John in CR to prescribe a 3 turn motor to do the same thing.
I thought the one undisputed truth of this topic, is that (without gearing) a high voltage is required to get a higher top speed
right?
Which end would yield
"max torque at 10-15mph"
with steep hills / heavy loads,
25+ inch wheel,
at lowest temps, or at least slowest ramping up of heat gain?
Fancy FOC 200A controller welcome, and a very low top speed not a problem.
Assuming no gearing, for purpose of this thought experiment.
Would like to get responses from a range of experienced members, even including @John in CR and @Balmorhea so long as civility. . .
right?
markz said:
Which end would yield
"max torque at 10-15mph"
with steep hills / heavy loads,
25+ inch wheel,
at lowest temps, or at least slowest ramping up of heat gain?
Fancy FOC 200A controller welcome, and a very low top speed not a problem.
Assuming no gearing, for purpose of this thought experiment.
Would like to get responses from a range of experienced members, even including @John in CR and @Balmorhea so long as civility. . .
Ianhill
1 MW
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I've never looked at it as max torque at 15mph becuase that happens from zero rpm.
I find the motors efficiency zone E.g so a 4krpm bldc motor will be best suited to running most of its time at least 2krpm and above on a graph we would see 3krpm and above for reaching the efficiency of motor.
Then i make sure there's more than enough torque to keep the ride singing at that efficient zone rpm without being overloaded so there's a bit in reserve ideally for long duration climbing.
The torque is always available below that rpm just means there's more heat soak associated in delivering it to the wheel so lots of zero rpm full starts will soon heat soak a poor designed system.
When I've overvolted my chaindrive inrunners ill push the rpm up so my 4.8krpm motor ended up at 8krpm but I dropped the gearing on the motor from 5-1 to 8-1 to help lower the top speed and the load on the motor I still ended up from 35mph to 48mph but i could do it for 15 mins travel 12miles or so and have a toasty cheep China 1600w motor been eating 4.4kw max.
ALSO by overvolting it pushes the efficiency point of a motor up the graph so it happens at a higher rpm but it also has a narrower window in some cases if the motor is close to it's insulation limits my 48v I run 18s about a 30% jump but had the luxury of gears and an Inrunner much better for overvolting than a massive hub due to shape and size.
Moral of the story pick a power need and select a motor lower voltage means quicker charge times in some cases but that's just cuz a 48v 500w charger will be same cost as the 84v and capacity comes into the charge time then.
I've got a 13s 10p pack and a 1500watt charger 4 to 24s and at 13s I can charge at 25amp 1500w total and be done in an hour but for 20s i need to drop the charge rate for the 1500w total so if a 13s and 20s pack has the same capacity no prob charge same time and pointless in changing anything but if I had the same 25ah batt capacity the charge time be around 3 hours but alot more range and larger batt so do I need the 60 mile hard riding range or keep my 20 mile bike that's under 40 kg and have the under hour charge time so i can have a blast about bite to eat and all over again.
Downside of that same capacity 13s vs 20s pack is by nature the less cells in parallel gives less c rating and if the motors a current hungry inrunner your not gonna have the power to get like the 15kw im aiming for but if it's a hub then more volts and less amps will suit the hubs needs and have a similar through put it's them down to motor dynamics.
I find the motors efficiency zone E.g so a 4krpm bldc motor will be best suited to running most of its time at least 2krpm and above on a graph we would see 3krpm and above for reaching the efficiency of motor.
Then i make sure there's more than enough torque to keep the ride singing at that efficient zone rpm without being overloaded so there's a bit in reserve ideally for long duration climbing.
The torque is always available below that rpm just means there's more heat soak associated in delivering it to the wheel so lots of zero rpm full starts will soon heat soak a poor designed system.
When I've overvolted my chaindrive inrunners ill push the rpm up so my 4.8krpm motor ended up at 8krpm but I dropped the gearing on the motor from 5-1 to 8-1 to help lower the top speed and the load on the motor I still ended up from 35mph to 48mph but i could do it for 15 mins travel 12miles or so and have a toasty cheep China 1600w motor been eating 4.4kw max.
ALSO by overvolting it pushes the efficiency point of a motor up the graph so it happens at a higher rpm but it also has a narrower window in some cases if the motor is close to it's insulation limits my 48v I run 18s about a 30% jump but had the luxury of gears and an Inrunner much better for overvolting than a massive hub due to shape and size.
Moral of the story pick a power need and select a motor lower voltage means quicker charge times in some cases but that's just cuz a 48v 500w charger will be same cost as the 84v and capacity comes into the charge time then.
I've got a 13s 10p pack and a 1500watt charger 4 to 24s and at 13s I can charge at 25amp 1500w total and be done in an hour but for 20s i need to drop the charge rate for the 1500w total so if a 13s and 20s pack has the same capacity no prob charge same time and pointless in changing anything but if I had the same 25ah batt capacity the charge time be around 3 hours but alot more range and larger batt so do I need the 60 mile hard riding range or keep my 20 mile bike that's under 40 kg and have the under hour charge time so i can have a blast about bite to eat and all over again.
Downside of that same capacity 13s vs 20s pack is by nature the less cells in parallel gives less c rating and if the motors a current hungry inrunner your not gonna have the power to get like the 15kw im aiming for but if it's a hub then more volts and less amps will suit the hubs needs and have a similar through put it's them down to motor dynamics.
Well, I'm not talking about starting from a standstill, but running along at say 20-25mph on the flat, when hitting the long steep hill with a heavy load.
I know that letting speed drop to, say 5mph leads to too much / fast heating up, so I picked that 10-15mph range
as a "target minimum" to shoot for, to try to avoid overheating.
My question here really is just about that "slow vs fast" winding issue
as with the OP, if there are advantages **in my scenario** to one over the other
and if a higher voltage always adds to that advantage, assuming an expensive controller.
______
Charging times and speed where efficiency is high are completely separate topics, afaic for another time?
I also did specify my question scenario, as not involving any gearing.
I know that letting speed drop to, say 5mph leads to too much / fast heating up, so I picked that 10-15mph range
as a "target minimum" to shoot for, to try to avoid overheating.
My question here really is just about that "slow vs fast" winding issue
as with the OP, if there are advantages **in my scenario** to one over the other
and if a higher voltage always adds to that advantage, assuming an expensive controller.
______
Charging times and speed where efficiency is high are completely separate topics, afaic for another time?
I also did specify my question scenario, as not involving any gearing.
ebike4healthandfitness
10 kW
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Balmorhea said:
Don't forget I want climbing as well.
Climbing with the least chance of over heating.
According to numbers I am getting from the ebikes.ca motor simulator higher voltage and lower amp controller combined with slower wind motor (Clyte H3525) is doing better than lower voltage and higher amp controller combined with faster wind motor (Clyte H3540) for heat build-up. This when both are set at the same climbing speed (unfortunately the simulator only has a few choices for controller when trying to restrict amps ---> 20amp and 35amp AOT460 and 25amp and 40 amp IRFB4110. So when I pair (for example) 72v with 20 amp AOT460 the 48v gets a 17% advantage because the only choice is 35amp AOT460 controller rather than a 30 amp controller. Reducing throttle on the 48v/35 amp brings the speed down to where the 72v/20 amp is.....but the result is still higher heat and greater power consumption.
P.S. Have you seen this ---> https://www.electricbike.com/hub-motor-pikes-peak/ (Apparently he was the first person to get to the top of Pikes Peak with a hub motor ebike. He used a slower wind direct drive (9C 2810) combined with very high volts and restricted amps and was fastest ebike to the top. Only the FFR (now called Outrider) Trikes were faster.)
John in CR
100 TW
All of the windings climb the same, have the same torque, same efficiency, and can run in the same size wheel. It only takes a different combination of voltage and current for the same power input to get the same torque, speed, and power out at the same efficiency. The only time a different winding needs to come into play is if you're already locked into a specific voltage. Anytime you manipulate the simulator to show different results it is the result of an apples and oranges comparison, and if you do so to show that the slow wind motor makes more torque, then it makes more heat, period.
ZeroEm
1 MW
Only two of them controllers can handle 72V; Grinfineon 40A and Phaserunner. Running only 15A best to stick with 52V.
Ianhill
1 MW
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I had an a2b metro with a mxus 4t and I run it on a 10s 330wh pack 40 batt amps sinewave 12fet irf4110 controller.
So it's the worst choice motor for low volts, it had a top speed of 16mph 2250watts max 53 phase amps and climbed real decent never got mildly warm.
Point is when I took it easy peddle along I still got 30 miles out of that pack averaging about 10wh per mile plodding on tarmac.
With that bike I made it single speed and made sure my peddling efficient zone (cadence) was at the 10-16mph zone so I could hold flat out and just assist myself a little, same ride no peddling 12 miles max range on flat. So i was 2/3rds that rides power most the time.
So it's the worst choice motor for low volts, it had a top speed of 16mph 2250watts max 53 phase amps and climbed real decent never got mildly warm.
Point is when I took it easy peddle along I still got 30 miles out of that pack averaging about 10wh per mile plodding on tarmac.
With that bike I made it single speed and made sure my peddling efficient zone (cadence) was at the 10-16mph zone so I could hold flat out and just assist myself a little, same ride no peddling 12 miles max range on flat. So i was 2/3rds that rides power most the time.
dogman dan
1 PW
The only reason to pick the slow winding, is to go slower with heavy loads without getting the motor into a hot rpm. I did that with my 1000w, 48v cargo bike that had the 20" rim and 10 turn wind. It worked for me, it was very slow, yet could haul 400 pounds up my mountain without overheating.
Or as said above, to slow the bike down when locked into a specific voltage.
And so on.
The original question was how practical is 72v for a bike meant for climbing and sub 28 mph speed. Not very, but it can be done with a very slow winding. The only reason to do that would be you are locked into a 72v battery.
What really works is a "motorcycle" setup that gives a bigger motor enough power to climb. To keep the speed down, run normal wind motors and 48v. Or even 36, but plenty of amps. You will have the power to climb that hill at 15 mph or more, not get hot, nor stick out like a "motorcycle with pedals".
That also worked great for me, with an old crystalyte 5304, 26" wheel, and 48v 40 amps. But it ran less efficient than the other bike, simply because I tended to ride it 30 mph, vs the 18 mph speed of the 10 turn 20 inch wheel.
So I had two bikes,, one designed to go slow with the slow wind, and the other designed to go 30 mph. Both climbed great with big cargo loads, but of course the big motor got up the hill faster.
Or as said above, to slow the bike down when locked into a specific voltage.
And so on.
The original question was how practical is 72v for a bike meant for climbing and sub 28 mph speed. Not very, but it can be done with a very slow winding. The only reason to do that would be you are locked into a 72v battery.
What really works is a "motorcycle" setup that gives a bigger motor enough power to climb. To keep the speed down, run normal wind motors and 48v. Or even 36, but plenty of amps. You will have the power to climb that hill at 15 mph or more, not get hot, nor stick out like a "motorcycle with pedals".
That also worked great for me, with an old crystalyte 5304, 26" wheel, and 48v 40 amps. But it ran less efficient than the other bike, simply because I tended to ride it 30 mph, vs the 18 mph speed of the 10 turn 20 inch wheel.
So I had two bikes,, one designed to go slow with the slow wind, and the other designed to go 30 mph. Both climbed great with big cargo loads, but of course the big motor got up the hill faster.
John in CR said:
"Locked into."
Your mean by certain voltages of battery and controller being way more plentiful and diverse, and costing a lot less? And by not having to change to higher ampacity plugs or modify your phase wires to be thicker?
That seems more like being unlocked to me. You know, choosing the thing that makes sense instead of letting the wrong motor winding choose for me.
ebike4healthandfitness
10 kW
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John in CR said:
I can see your point after looking at a chart like this:
And if the goal is limited power then maybe even the lowest voltage is best?
John in CR
100 TW
Balmorhea said:
No, I meant you already have the battery and charger(s) for a specific voltage. Stick to ripping off the gullible by selling pedal bikes with prices in the thousands of dollars using the sales pitch that grams make a difference.
John in CR
100 TW
Just like his goal with pedal bikes (ie trying to separate you from as much money as possible), if you listen to Balmorhea you'll have to buy all new every time you upgrade your ride after the initial setup that gets you hooked, and with each incremental step you'll have to spend on new stuff each time. Instead of buying a crappy inflexible controller to start along with a motor that's stressed from the getgo, if you treat your ebike purchases as investments with room to grow, you'll save money in the long run as well as have a better performing ebike instead of one quite likely to suffer a heat related failure because you underestimated the impact of steep ascents.
goatman
10 MW
i was going to say the same thing, a cheap ass 48v/ 20amp controller/3525 plus a hill and he will be walking home, he wont be pedalling it
phaserunner, 20to60 amps, 36vto72v. get a battery that handle the amps. and if you dont like the 3525 , get the 3540
atleast the phaserunner is programmable, reliable, high quality, waterproof, tiny
phaserunner, 20to60 amps, 36vto72v. get a battery that handle the amps. and if you dont like the 3525 , get the 3540
atleast the phaserunner is programmable, reliable, high quality, waterproof, tiny
Ianhill
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Just one point I want to add is I hear people say higher volts still goes faster towards the end of the discharge.
FALSE.
There is more varience in voltage range the more cells you add 1s=.8v 2s=1.6v and so on, so the reverse is true and theres more depending how well the c rating of the pack is managed to get the watts out towards the end of the cycle so cells delivering close on c rating will also feel like theres a big speed drop and lack of climb ability.
For those reason stay low as possible and have more discharge than needed rather than go close to the wire for the sake of capacity based cells because that end 30% will feel crap anyway.
Another thing is how much watts the motor sees from start of discharge to end
EG 1s 10amp system would be 40 watt and drop 8watt to 32 throughout the cycle
2s 10 amp system 80 16watt drop to 64 and so on
More the volts more the total watts difference across the cycle.
FALSE.
There is more varience in voltage range the more cells you add 1s=.8v 2s=1.6v and so on, so the reverse is true and theres more depending how well the c rating of the pack is managed to get the watts out towards the end of the cycle so cells delivering close on c rating will also feel like theres a big speed drop and lack of climb ability.
For those reason stay low as possible and have more discharge than needed rather than go close to the wire for the sake of capacity based cells because that end 30% will feel crap anyway.
Another thing is how much watts the motor sees from start of discharge to end
EG 1s 10amp system would be 40 watt and drop 8watt to 32 throughout the cycle
2s 10 amp system 80 16watt drop to 64 and so on
More the volts more the total watts difference across the cycle.
MadRhino
100 GW
The difference need to be expressed as a percentage. If a slow winding does 30 mph at 72v it will have the same % speed drop at lvc as a fast winding doing the same top speed at 48v, simply because the fast winding will drop more rpm per volt, proportionally.
Ianhill
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MadRhino said:
Learn something everyday never thought of that.
So to lose less rpm as possible use low volts and high turn counts
Down side little current handling and the speed is gonna be crawling so efficiency will suffer.
Think between you all its answered here
John in CR
100 TW
Ianhill said:
That's not at all what MadRhino is saying. He's saying it doesn't make any difference, because the % change in voltage is the same. Just give up trying to invent a condition where it's better to use a slow wind motor, because there isn't one unless you want to go really slow and you're sure you'll never want better performance.
To me it's pitiful that anyone needs to suffer with a slower bike at the end of a ride than the beginning, and that's especially true for those who want to stick to some arbitrary letter of the law written by people who are extremely prejudiced against ebikes. The way around the problem is to build the bike with excess capability and limit the top speed via the controller. Then you can ride the speed you want at all points in the discharge cycle as well as on uphill grades and into headwinds.
ebike4healthandfitness
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John in CR said:
One thing I have noticed when comparing Clyte H3548 and Clyte H3525 at higher power levels in the motor simulator is that the slower wind Clyte H3525 at high voltage will do better than the faster wind Clyte H3548 at low voltage.....in climbing and top speed.
H2525 @ 72v with 20" wheel:
32.5 kph climbing 14% grade with 61.1 watt-hours per km power consumption
43.3 kph top speed on flat ground
H3548 @ 36v with 20" wheel:
22.6 kph climbing 14% grade with 62.9 watt-hours per km power consumption
40.6 kph top speed on flat ground
https://ebikes.ca/tools/simulator.html?motor=M3525&cont=PR&batt=B7210_DT&wheel=20i&grade=14&hp=0
https://ebikes.ca/tools/simulator.html?motor=M3548&cont=PR&batt=B3626_GA&wheel=20i&grade=14&hp=0
https://ebikes.ca/tools/simulator.html?motor=M3525&cont=PR&batt=B7210_DT&wheel=20i&grade=0&hp=0
https://ebikes.ca/tools/simulator.html?motor=M3548&cont=PR&batt=B3626_GA&wheel=20i&grade=0&hp=0
With the H3548 being almost twice the wind as the H3525 the results should be a lot closer. The only thing I can think of is that the phase wires are too thin to optimally handle the higher current needs of the 36v and this is why the slower wind H3525 is so much better at climbing.
MadRhino
100 GW
You are setting limits too low for the faster KV.
I have built a lot of those Clyte h motors, slow, fast and very fast. I was feeding them 10kw. The faster windings were doing better, but none of them were lasting very long. After accumulating half a garbage can of fried motors, I started building with bigger ones.
It doesn’t hurt to ride 30 on a bike that could do 60, either because you limited it to 30, or you just twist half throttle. And, when the situation occurs, you will be able to maintain 30, whatever climbing or voltage drop.
Building slow is a must, only for riding VERY slow.
I have built a lot of those Clyte h motors, slow, fast and very fast. I was feeding them 10kw. The faster windings were doing better, but none of them were lasting very long. After accumulating half a garbage can of fried motors, I started building with bigger ones.
It doesn’t hurt to ride 30 on a bike that could do 60, either because you limited it to 30, or you just twist half throttle. And, when the situation occurs, you will be able to maintain 30, whatever climbing or voltage drop.
Building slow is a must, only for riding VERY slow.
John in CR
100 TW
ebike4healthandfitness said:
While I wouldn't put anything past that company, which sells substandard products at premium prices only for export outside of China, since they can't compete in the Chinese market, your imputs still lead to an apples and oranges comparison. The simulator now allows you to vary the Kv of motors for easy apples and apples comparisons, so all you have to do is make sure your battery pack and controller inputs vary in resistance by the correct proportions for identical losses in the wiring outside the motor to demonstrate that fast or slow winds have identical results, which is the correct answer. Just as easily as you entered inputs that show slow winds climb better, I could use apples and oranges inputs to show that fast wind motors climb better.
The bottom line is that slow wind motors are easier to burn up because their current handling is proportionately lower making it easier to unwittingly give them too much current. To get to the same speed means running a higher voltage, so for the same capacity the parallel structure of the battery is smaller, which makes it more prone to failure. That also means the BMS will have a proportionately higher part count, which proportionately increases its likelihood of failure as well. Last but not least, your upgrade path in the event you want more performance is more costly, because it means you need to buy a new motor.
