Well, yes. I didn't think more volts would result in more low end torque, but it clearly did when I went from 37v Lifepo4 to 48v Lipo. I kept my amps limited to 21a, and it consequently pulled 1050watts peak on lipo. My hill climbing was noticeably faster as well as accelerating. I am running a 6 turn Mac geared hub motor. It's cool that you can increase torque without upping the amps, though I did find that efficiency went down quite a bit on the higher voltage, and that was with going the same cruising speeds. That's likely due to using even less % throttle than normal, I am guessing.
Higher voltage = more torque?
- Thread starter veloman
- Start date
docnjoj
1 GW
It certainly makes sense! When I was running 54 volts of fatpacks with my 9C it flew off the line and across streets.It also gave me 20 mile range just like my Ping with 15 useful AH/ I had 8 AH or so with the Fatpacks but did control the throttle a bit! Now with 36 volts of Ping it is a bit "sedate". Oh well, enough of former triumphs!
otherDoc
otherDoc
iovaykind
10 kW
Torque comes from more power. Power is directly related to amps and volts.. as a result, increasing voltage increases torque. It also increases top speed because the motors have a rpm/volt rating. Amps will help you get to your top speed faster but will not help with top speed.
dogman dan
1 PW
A better way to put it is, more watts is more torque, always. Say you went from 36v 40 amp controller to a 72v 20 amp controller. The 72v rig might be faster, but it might take of slower than the 48v one. Both have the same watts, so should have similar torque. But one might feel torqueier than the other to the rider.
But that's a pretty unusual example, Typically folks that up the voltage don't decrease the amps so much. So in 99% of cases the higher voltage is going to be higher wattage, and therefore more power, more speed, and more torque.
You should see what 110v does for torque. Yahooo.
In some cases amps does increase speed. for example, my 72v 20 amp controller maxes out at 35 mph. That's because you just can't hit 40 mph with 1400 w. too much wind resistance. But the 72v 40 amp controller is able to breifly touch 40 mph, and cruise at 39 mph. Now you have the wattage for 40 mph, because you increased the amps.
But at 48v speeds, you don't tend to see much difference in speeds by adding amps. You already have enough with 20 amps.
But that's a pretty unusual example, Typically folks that up the voltage don't decrease the amps so much. So in 99% of cases the higher voltage is going to be higher wattage, and therefore more power, more speed, and more torque.
You should see what 110v does for torque. Yahooo.
In some cases amps does increase speed. for example, my 72v 20 amp controller maxes out at 35 mph. That's because you just can't hit 40 mph with 1400 w. too much wind resistance. But the 72v 40 amp controller is able to breifly touch 40 mph, and cruise at 39 mph. Now you have the wattage for 40 mph, because you increased the amps.
But at 48v speeds, you don't tend to see much difference in speeds by adding amps. You already have enough with 20 amps.
vanilla ice
1 MW
This is not always true either.. in a lot of cases more amps will increase the top speed a bike can reach.iovaykind said:
I guess I just thought that at low end, all those extra watts would just be waste heat. It was pulling about 240watts more on the lipo.
I wish I could read my turnigy watt meter easier when riding. I have a chance at night, but not during the day unless I get really close, in the shade. The Mac seems quite efficient though, even at low end. It always seems like I'm at 70-80% efficiency, Just by knowing how much power it takes to move myself on a bike. It really does quite a good job with only one transmission gear.
I wish I could read my turnigy watt meter easier when riding. I have a chance at night, but not during the day unless I get really close, in the shade. The Mac seems quite efficient though, even at low end. It always seems like I'm at 70-80% efficiency, Just by knowing how much power it takes to move myself on a bike. It really does quite a good job with only one transmission gear.
geetarboy
100 W
I notice a big difference between 100v and 125v on take-off, and as Dogman said it's probably watts. My max amps on the CA is limited to 50. So, 5000 peak watts compared to 6250. Mathematically it's 25% more, but it sure feels like more than that on WOT.
LI-ghtcycle
10 MW
iovaykind said:
This has been my experience in general, all things being equal, watts is power, however, if you have more amps than volts, generally speaking, you get more torque with close cousins, for example:
1) 36V 20A = 720W
2) 48V 15A = 720W
However, when using the same DD hub motor, I have found that:
1) Generally climbs hills with less complaints, with less top end, but quicker acceleration to it's diminished top end.
2) Generally complains more on hills, but has a higher top end and takes a little longer to get there.
There are a bunch more variables too as to what kind of motor you have, for example, when I used my 350W Amped Geared Motor, I thought I had it made, light bike, 53V battery, I should fly up hills right? Wrong.
I was disappointed when climbing the local 10% grade, and shaking my head when I didn't get the performance I expected.
Two things I didn't realize at the time: 1) the 350W geared motor had a controller putting out only 15A VS my father's 9 x 7 DD's 22A, and 2) the geared motor was optimized in it's gearing for 36V! Until 72V+ that geared motor doesn't really show marked increase in performance, unless in a smaller diameter wheel (gearing change) and with that very same battery, that clunky over weight DD at 36V, came alive at 53V!!
I was so happy when my dad agreed to try swapping motors, because he was happier with geared at 36V, and at 53V I was having a blast going up hills like crazy with pedaling now only optional!
Now with my current mid-drive, it's a higher Kv than my trusty 9 x 7 DD hubbie, it more than twice the Kv (12 vs 28) so the motor is harder to get meshed with my pedaling cadence than it was with the 9 x 7, but not impossible, just have to adjust, hopefully my new first stage gearing will match better to my cadence, so it's as much as how the motor behaves at a given voltage VS another too, and I think most of the high Kv motors are great, and can give you plenty of power off the line, but not all of those will also climb hills well, or as strong as others.
So far my current GM "trike" motor really likes to go faster to make the torque (momentum must count here too I suppose) for climbing that my 9 x 7 did, but also the 9 x 7 seemed impossible to bog down where as this one likes a little help, even though it will still do 70% of the work.
I'm curious to see how it performs hill climbing with more low end friendly gearing.
gtadmin
10 kW
If phase amps are identical then you have identical motor torques irrespective of battery voltage (at least that is my understanding). The thing is the phase amps won't be identical and will be higher for the higher battery voltage for the same battery amperage draw.
LI-ghtcycle
10 MW
gtadmin said:
Yeah, I'm probably not understanding the way they work exactly, but IDK, it seems to work this way with the motors I have tried so far, I am by no means any kind of expert, just a "shade tree" back yard mechanic / tinkerer. :wink:
ElectroSurf3r
10 W
P=IV
P=Tw
So yes, increased Voltage means higher Power and Torque... and more grins
But if you want a noticeably higher top end, increase the voltage. It has a much more direct relationship with rpm.
P=Tw
So yes, increased Voltage means higher Power and Torque... and more grins
More amps = more power to fight air drag, which increases top speed slightly.vanilla ice said:
But if you want a noticeably higher top end, increase the voltage. It has a much more direct relationship with rpm.
John in CR
100 TW
Our motors have a torque constant, so if current getting to the motor was identical, then the torque would be too as would acceleration. However we do see an increase in acceleration come with an increase in voltage with the same battery side current limits, so something different has to be going to the motor as a result of PWM.
Hopefully one of the gurus will step in and explain the effect, because I'm pretty sure the explanations above aren't really on target. Maybe it's phase current multiplication that increases with voltage.
John
Hopefully one of the gurus will step in and explain the effect, because I'm pretty sure the explanations above aren't really on target. Maybe it's phase current multiplication that increases with voltage.
John
Kingfish
100 MW
Mathematically –
Power (P) = Torque (τ) * Angular Velocity (ω), and
P = Current (I) * Volts (V)
From Doing the Math, We already know that V == τ;
therefore change (∆) is directly relative; ∆V == ∆τ
If τ = 2rBIL where:
and constant Current (I)...
once again if ∆V == ∆τ, and all other factors being constant
then ∆V == ∆τ == ∆B, and that is the reason for the perceived improvement.
~KF
Power (P) = Torque (τ) * Angular Velocity (ω), and
P = Current (I) * Volts (V)
From Doing the Math, We already know that V == τ;
therefore change (∆) is directly relative; ∆V == ∆τ
If τ = 2rBIL where:
- r = radius
B = Magnetic field strength in Tesla
I = Current
L = length of conductor (turns)
and constant Current (I)...
once again if ∆V == ∆τ, and all other factors being constant
then ∆V == ∆τ == ∆B, and that is the reason for the perceived improvement.
~KF
John in CR
100 TW
neptronix said:
That makes sense since the controller remains in current limiting for longer. I'd love to have a controller that ran at 250V and could handle 100A/250A or 150A/400A (battery/phase) with efficiency and durability. Current limiting makes for nice flat performance curves that you can feel.
Drunkskunk
100 GW
Kingfish said:
To translate for the non engineers,
More Voltage = More Grins
Kingfish
100 MW
With constant current and an increase in voltage, the induced magnetic field strength (B) MUST proportionally increase. The magnets react to the increased field strength with greater Force (F). Thus ~ the rider experiences “greater torque” and “wider torque band”… which is essentially and completely a true result :wink:Drunkskunk said:Kingfish said:
To translate for the non engineers,
More Voltage = More Grins
Math can be fun!
With many happy grins, KF
John in CR
100 TW
Kingfish said:With constant current and an increase in voltage, the induced magnetic field strength (B) MUST proportionally increase. The magnets react to the increased field strength with greater Force (F). Thus ~ the rider experiences “greater torque” and “wider torque band”… which is essentially and completely a true result :wink:
Math can be fun!
With many happy grins, KF
So our BLDC motors don't have a torque constant per se, since we are limiting current instead of "drawing" whatever current the motor will take like more traditional motors???
Alan B
100 GW
Higher voltage at equal battery current delivers more power which makes higher phase current for the motor at a given voltage. Phase current makes torque so you get more.
RallySTX
10 kW
MMMMMM, Tourqe is goooood! 8)
Brian L.
Brian L.
Hummina Shadeeba
10 MW
I'm still confused by voltage in a motor. will a motor perform better with higher voltage (greater acceleration) or can the same performance be produced with either voltage? Can more amps be pushed through for more acceleration with the higher voltage ?
wesnewell
100 GW
See this thread.
https://endless-sphere.com/forums/viewtopic.php?f=3&t=81261
https://endless-sphere.com/forums/viewtopic.php?f=3&t=81261
Hummina Shadeeba
10 MW
Same performance possible regardless of voltage
