Hawk521
1 mW
Sun EZ-3 HD USX recumbent trike - Adding electric power.
The trike design led me to a plan to utilize the left rear axle for the motor
driven wheel and leave the right rear axle/wheel as the peddle driven wheel.
Each wheel is locked to its respective axle with a good heavy duty key, and
both axles are carried by ball bearings suitable for a heavy duty load. This
approach might seem odd but it does keep things simple.
Thus I began designing and acquiring off-the-shelf hardware that I intend to use
for this project:
1. Ordered an extended axle to replace the non-drive left axle.
This is simply a right side axle to be installed on the left side. It
provides about 2 inches of mount room for a final drive pulley.
2. Ordered a heavy duty freewheel and hub adapter to mount the motor drive
freewheel on the inside end of the above axle. Plan is to afix the final drive
pulley to this freewheel thus making it simple to peddle the trike w/o
motor assist. Nothing in the drive/pulley/belt assembly will need to rotate
when being peddled w/o motor assist.
3. Ordered a jackshaft assembly (solid aluminum) w/ball bearing shaft
from a go-kart parts supplier. Need this to reduce the overall drive
rpm to something suitable for directly driving the left rear axle. On
my trike's 20" wheels, 100 rpm of the rear axle equals ~6 mph.
4. Ordered 4 pulleys. HTD 5 mm pitch x 25mm width (2 @ 24 teeth, 2 @ 80 teeth)
Plan is to utilize all belt drive in two reduction stages. Hopefully this
will result in a fairly quiet drive system. My goal is that only the motor
will be audible - and even that will hopefully not be obnoxious.
Note: The pulleys I chose should yield approx 18 mph at 3000 rpm at the motor.
And if needed I can switch out a pulley or two to move that sweet spot
up or down the rpm range.
5. Will order the drive belts after I have finalized the drive components layout
and select a motor.
All the above leads me to the motor / controller / battery choices. Truly the
big ticket items! I have a vision of what I want, but could use some advice on
how to best achieve it.
a) I'd love to get a 3kw to 5kw BLDC motor that could handle 24v/36v/48v, yet
initially I would run the motor at 24v. I cannot fathom ever going past 48v as my
need for speed expired about 15 years ago. Am hopeful that my needs can be
met at the 24 volt level. Essentially I am willing to buy a bigger motor than
I need initially, in the hope that should I need more power out of it, I will
have the option to do so by adding more battery, volts, amps, etc. Also, I would
think that oversizing the motor a bit will prevent some overheating issues!?
b) Along with above motor I would like to purchase a controller that allows:
- use at 24 volts (and optionally 36 or 48 volts if needed in the future)
- provide reasonably smooth throttle (speed) control so the bike motor doesn't
act like it is simply ON or OFF. I'd like to be able to transition to the motor
without having it hammer the freewheel assembly too harshly.
c) For batteries my ultimate will be a LiFePO4 battery pack with 10-15 Ah or more.
But initially I would like to test with a pair of SLA batteries that are cheap.
(Or is there good reason to NOT try the SLA batteries at all?) Who knows, if I
don't utilize the motor too much I might be by for a while with SLA batteries.
I'm up for any advice or council on this project. Realizing that many of you have
gone down this road a time or two I will value your input. Do my requirements
make sense? Any obvious choices I should consider?
Thanks.
-hawk521
The trike design led me to a plan to utilize the left rear axle for the motor
driven wheel and leave the right rear axle/wheel as the peddle driven wheel.
Each wheel is locked to its respective axle with a good heavy duty key, and
both axles are carried by ball bearings suitable for a heavy duty load. This
approach might seem odd but it does keep things simple.
Thus I began designing and acquiring off-the-shelf hardware that I intend to use
for this project:
1. Ordered an extended axle to replace the non-drive left axle.
This is simply a right side axle to be installed on the left side. It
provides about 2 inches of mount room for a final drive pulley.
2. Ordered a heavy duty freewheel and hub adapter to mount the motor drive
freewheel on the inside end of the above axle. Plan is to afix the final drive
pulley to this freewheel thus making it simple to peddle the trike w/o
motor assist. Nothing in the drive/pulley/belt assembly will need to rotate
when being peddled w/o motor assist.
3. Ordered a jackshaft assembly (solid aluminum) w/ball bearing shaft
from a go-kart parts supplier. Need this to reduce the overall drive
rpm to something suitable for directly driving the left rear axle. On
my trike's 20" wheels, 100 rpm of the rear axle equals ~6 mph.
4. Ordered 4 pulleys. HTD 5 mm pitch x 25mm width (2 @ 24 teeth, 2 @ 80 teeth)
Plan is to utilize all belt drive in two reduction stages. Hopefully this
will result in a fairly quiet drive system. My goal is that only the motor
will be audible - and even that will hopefully not be obnoxious.
Note: The pulleys I chose should yield approx 18 mph at 3000 rpm at the motor.
And if needed I can switch out a pulley or two to move that sweet spot
up or down the rpm range.
5. Will order the drive belts after I have finalized the drive components layout
and select a motor.
All the above leads me to the motor / controller / battery choices. Truly the
big ticket items! I have a vision of what I want, but could use some advice on
how to best achieve it.
a) I'd love to get a 3kw to 5kw BLDC motor that could handle 24v/36v/48v, yet
initially I would run the motor at 24v. I cannot fathom ever going past 48v as my
need for speed expired about 15 years ago. Am hopeful that my needs can be
met at the 24 volt level. Essentially I am willing to buy a bigger motor than
I need initially, in the hope that should I need more power out of it, I will
have the option to do so by adding more battery, volts, amps, etc. Also, I would
think that oversizing the motor a bit will prevent some overheating issues!?
b) Along with above motor I would like to purchase a controller that allows:
- use at 24 volts (and optionally 36 or 48 volts if needed in the future)
- provide reasonably smooth throttle (speed) control so the bike motor doesn't
act like it is simply ON or OFF. I'd like to be able to transition to the motor
without having it hammer the freewheel assembly too harshly.
c) For batteries my ultimate will be a LiFePO4 battery pack with 10-15 Ah or more.
But initially I would like to test with a pair of SLA batteries that are cheap.
(Or is there good reason to NOT try the SLA batteries at all?) Who knows, if I
don't utilize the motor too much I might be by for a while with SLA batteries.
I'm up for any advice or council on this project. Realizing that many of you have
gone down this road a time or two I will value your input. Do my requirements
make sense? Any obvious choices I should consider?
Thanks.
-hawk521