onloop said:
@Vedder. Can you discuss in more detail what you believe to be the best setup for eboards and why?
torqueboards said:
In the end - the question seems more broad than anything. It's kind of tough to have 1 specific setup for an eboard to be lightweight 10-12 lbs, powerful 30+ mph, hill climber (20% steep hills), distance runner (12-15miles).
@Vedder - Still want to hear what you have to say
yes, i suppose my question was not specific.... so let me clarify further.
Your system is designed for higher voltage (so higher than widely used 24v)... I assume thats because you are confident it is likely to be more efficient running higher voltage as opposed to drawing more current. Also It should generate less heat and you can use smaller wires.
So lets say for now higher voltage is generally 'electrically' more efficient. What do you believe is the best way to get the power to the wheels on a skateboard.... to clarify i am specifically referring to Electro-mechanical Efficiency & Drive train Design limitations.... (the question about dual motors / single motors / flat riding / hill climbing /etc... is secondary)
Below are just a few examples of some different setups that all should deliver a similar top speed. So my question is what (in your opinion) is going to be more/most efficient...
example #1
Drive: 14 teeth (any smaller and teeth in mesh becomes an issue - unless you have really long motor mounts which are more prone to flex or need to use idlers)
Driven: 36 teeth (as big as i'm prepared to go on this wheel using 5mm pitch)
Max Battery Voltage (V): 42.0 V - 10S lipo
Motor Rounds per Voltage (kV): 170 kv
Tire Diameter: 3.25 (83mm)
Final Ratio (FDR): 2.571
Engine rpms: 7 140 rpm
Top Speed: 43.13 km/h (26.85 mph)
CONS
1. not many 170 KV motors to choose from. (only two available on hobbyking 6374's)
2. '2.571" is not much reduction - higher peak current draws - more load/stress on motor - maybe not efficient
3. need 10s charger
4. lower capacity battery for size/weight
5. the lower kV motor will have greater resistance in its windings. more heat.
PROS
1. USE 5mm pitch pulley
example #2
Drive: 17 teeth (any smaller and teeth in mesh becomes an issue - unless you have really long motor mounts which are more prone to flex or need to use idlers)
Driven: 60 teeth (as big as i'm prepared to go using this wheel with 3mm pitch)
Max Battery Voltage (V): 42.0 V - 10S lipo
Motor Rounds per Voltage (kV): 245 kv
Tire Diameter: 3.25 (83mm)
Final Ratio (FDR): 3.529
Engine rpms: 10 290 rpm
Model Speed: 45.29 km/h (28.19 mph)
CONS
1. you will need to use 3mm pitch pulley to allow this to physically fit - 3mm is not widely tested and maybe won't work well. - 3mm is maybe not suitable for such high RPM, i think for the torque we have on eboards to use 3mm pitch RPM needs to be under 10,000RPM)
2. decent reduction but still not great when in compared to some experienced ebike builders who talk 7:1 or greater for efficiency.
3. need 10S charger
4. lower capacity battery for size/weight
PROS
1. 245KV motors are fairly common
example #3
Drive: 17 teeth (any smaller and teeth in mesh becomes an issue - unless you have really long motor mounts which are more prone to flex or idlers)
Driven: 60 teeth (as big as i'm prepared to go using this wheel with 3mm pitch)
Max Battery Voltage (V): 33.6 V - 8S
Motor Rounds per Voltage (kV): 290 kv
Tire Diameter: 3.25 - 83mm
Final Ratio (FDR): 3.529
Engine rpms: 9 744 rpm
Top speed: 42.88 km/h (26.69 mph)
CONS
1. you will need to use 3mm pitch pulley to allow this to physically fit - Also 3mm is not fully tested and maybe won't work well. -
I THINK 9700 RPM IS GOOD FOR THIS 3MM BELT
2. decent reduction but still not great when compared to some experienced ebike builders who talk 7:1 or greater for efficiency.
3. need 8S charger
4. lower capacity battery for size/weight
PROS
1. 290KV motors are fairly common
example #4
Drive: 17 teeth
Driven: 60 teeth
MAX Battery Voltage (V): 25.2 V - 6S
Motor Rounds per Voltage (kV): 390 kv
Tire Diameter: 3.25 - 83mm
Final Ratio (FDR): 3.529
Engine rpms: 9 828 rpm
Top Speed: 43.25 km/h (26.92 mph)
CONS
1. you will need to use 3mm pitch pulley to allow this to physically fit - Also 3mm is not fully tested and maybe won't work well.
I THINK 9800 RPM IS PROBABLY GOOD FOR THIS 3MM BELT
2. decent reduction but still not great when compared to some experienced ebike builders who talk 7:1 or greater for efficiency.
3. not many 390KV motors to choose from
4. slightly higher peak amp draw
PROS
1. lots of chargers to choose from
2. larger capacity battery / lower weight
example #5
Drive: 14 teeth (any smaller and teeth in mesh becomes an issue - unless you have really long motor mounts which are more prone to flex or need to use idlers)
Driven: 36 teeth (as big as i'm prepared to go on this wheel using 5mm pitch)
MAX Battery Voltage (V): 25.2 V - 6S
Motor Rounds per Voltage (kV): 270 kv
Tire Diameter: 3.25 (83mm)
Final Ratio (FDR): 2.571
Engine rpms: 6804 rpm
Top Speed: 41.10 km/h (25.58 mph)
CONS
1. '2.571" is not much reduction - MUCH higher peak current draws - more load/stress on motor - maybe not efficient
PROS
1. USE 5mm pitch pulley
2. chargers readily available
3. motors are readily available
SO VEDDER...to get to my point!... there are probably several other setups (and 1000's more PROS/CONS) that we can discuss that will give us a desirable top speed / performance...
so what do you believe to be the most efficient..
Once we can all agree I suppose we must then agree what setup is the most cost effective / feasible! then we must agree on the best balance between efficiency, reliability, cost, performance.