Electric Ducted Fan Powered Longboard Help Please!

[Doug Hill]

Hello,
I really want to power my longboard. I don't want to buy a Boosted Board (As much as I would love to have one) because they are super expensive so I thought EDFs may be the way to go. The thing is, I have no idea how much power/size of EDF I need and how I should power them (What kind of battery I need). I'm okay with soldering and electronics but I need some guidance/help, So If you could help me, I'd Love it.

Thanks,
Doug

 

[Gryd3]

Hello,
I really want to power my longboard. I don't want to buy a Boosted Board (As much as I would love to have one) because they are super expensive so I thought EDFs may be the way to go. The thing is, I have no idea how much power/size of EDF I need and how I should power them (What kind of battery I need). I'm okay with soldering and electronics but I need some guidance/help, So If you could help me, I'd Love it.

Thanks,
Doug

No idea :s
I don't board, and I'm pretty new to the world of fans.
You should google around for 'thrusters' and 'snowboards' though..
I've seen a couple guys make these things with 40+kg of thrust... but the packs only run for a few minutes.
They use ducted fans in their project, I suggest you do the same

 

[Doug Hill]

No idea :s
I don't board, and I'm pretty new to the world of fans.
You should google around for 'thrusters' and 'snowboards' though..
I've seen a couple guys make these things with 40+kg of thrust... but the packs only run for a few minutes.
They use ducted fans in their project, I suggest you do the same

Neat, Thanks Ill have another look around

 

[Alec_t]

Cool, but I would expect a fan (even a ducted one) to be very inefficient compared to direct motor drive of the wheels. Have you done any research on that? Are you set on using a fan despite its inefficiency?

 

[Doug Hill]

Cool, but I would expect a fan (even a ducted one) to be very inefficient compared to direct motor drive of the wheels. Have you done any research on that? Are you set on using a fan despite its ineffiency?

How hard would it be to make one with a motor Drive?

 

[Alec_t]

I guess that would depend a lot on your engineering ability, and ability to source motors, gears etc.

 

[Gryd3]

Cool, but I would expect a fan (even a ducted one) to be very inefficient compared to direct motor drive of the wheels. Have you done any research on that? Are you set on using a fan despite its inefficiency?

He's absolutely right... this project has a 'cool' factor. There is a reason the projects I have seen like this only last a few minutes tops

How hard would it be to make one with a motor Drive?

There are kits and tutorials everywhere. They are typically built after a visit to a local hobby store to buy a R/C brushless motor, a motor driver, a simple receiver, and a cheap transmitter.
The engineering skills come into play figuring out how to mount the motor to one or more of the wheels on the board. (Or adding an additional wheel)
The motors usually have a very high RPM, so gearing is a must... again, this goes back to engineering or the good ol' "trial and error" . I've seen belt and chain drives used for this.

 

[Doug Hill]

He's absolutely right... this project has a 'cool' factor. There is a reason the projects I have seen like this only last a few minutes tops

There are kits and tutorials everywhere. They are typically built after a visit to a local hobby store to buy a R/C brushless motor, a motor driver, a simple receiver, and a cheap transmitter.
The engineering skills come into play figuring out how to mount the motor to one or more of the wheels on the board. (Or adding an additional wheel)
The motors usually have a very high RPM, so gearing is a must... again, this goes back to engineering or the good ol' "trial and error" . I've seen belt and chain drives used for this.

Hmm Okay, So I can do the attachment of the belt to the wheel, What size of motor would it be? 12v? Then I'd use a smallish belt which goes round an extension attached to one of the back wheels. Ill do some research.

Would I go for a motor like this? or is it too small?

 

[Gryd3]

Hmm Okay, So I can do the attachment of the belt to the wheel, What size of motor would it be? 12v? Then I'd use a smallish belt which goes round an extension attached to one of the back wheels. Ill do some research.

Would I go for a motor like this? or is it too small?

Depends on the speed/acceleration you want .
It looks reasonable to me, but it may struggle up hill.
I lack in the math here, I have seen other projects use closer to 1000W capable motors and they seem to do incredibly well.

 

[Doug Hill]

Depends on the speed/acceleration you want .
It looks reasonable to me, but it may struggle up hill.
I lack in the math here, I have seen other projects use closer to 1000W capable motors and they seem to do incredibly well.

So more like this?

EDIT: Nevermind with that one its wayyy too big, Ill keep looking

-- I'd use one or two batteries like these

-- I found another project and he used a 400kV 1560W Motor Like these

EDIT#2: This is a cool instructable on how, But I lack the electrical skills to make this D:
If it was slightly more simple, I'd make this right away!

 

[Gryd3]

So more like this?

EDIT: Nevermind with that one its wayyy too big, Ill keep looking

-- I'd use one or two batteries like these

-- I found another project and he used a 400kV 1560W Motor Like these

EDIT#2: This is a cool instructable on how, But I lack the electrical skills to make this D:
If it was slightly more simple, I'd make this right away!

We can help with the electrical!
You just need to plan out how you want to control it.
As far as range+battery life is concerned, you can easily add more batteries in parallel later.

 

[Doug Hill]

We can help with the electrical!
You just need to plan out how you want to control it.
As far as range+battery life is concerned, you can easily add more batteries in parallel later.

Awesome. Thanks! I'll have a look online on how to control a motor wirelessly

What kind of controller Should I use, I think Ill control the motor With radio as its easy, but I dont want to lug around a huge controller..

 

[Gryd3]

Awesome. Thanks! I'll have a look online on how to control a motor wirelessly

You need a transmitter and receiver.
You can use almost anything for this from taking apart a cheap R/C from radioshack or buying a transmitter/receiver pair online (often used with arduino) . The high end would be hitting a hobby RC store and buying a higher end transmitter and a 2-channel (or more) receiver.
Keep in mind that the cheaper methods are a little more difficult to fine-tune and may pick up interference from other devices that operate on the same frequency. The hobby store solution is a little more expensive, but you have more control over the frequency, and the outputs.
That's the first stage... the second stage is connecting the radio/wireless receiver to the motor, or motor controller

 

[Doug Hill]

You need a transmitter and receiver.
You can use almost anything for this from taking apart a cheap R/C from radioshack or buying a transmitter/receiver pair online (often used with arduino) . The high end would be hitting a hobby RC store and buying a higher end transmitter and a 2-channel (or more) receiver.
Keep in mind that the cheaper methods are a little more difficult to fine-tune and may pick up interference from other devices that operate on the same frequency. The hobby store solution is a little more expensive, but you have more control over the frequency, and the outputs.
That's the first stage... the second stage is connecting the radio/wireless receiver to the motor, or motor controller

Would I need a 2-Channel receiver If I'm only using one controller?

Edit- Also, would this be a good parts list/what do I need?

Motor
Gearing
A Couple of Batteries
Brushless ESC (But not sure if it is over kill..)
Transmitter/receiver (Not sure)
And wires, soldering iron etc...

 

[Doug Hill]

You need a transmitter and receiver.
You can use almost anything for this from taking apart a cheap R/C from radioshack or buying a transmitter/receiver pair online (often used with arduino) . The high end would be hitting a hobby RC store and buying a higher end transmitter and a 2-channel (or more) receiver.
Keep in mind that the cheaper methods are a little more difficult to fine-tune and may pick up interference from other devices that operate on the same frequency. The hobby store solution is a little more expensive, but you have more control over the frequency, and the outputs.
That's the first stage... the second stage is connecting the radio/wireless receiver to the motor, or motor controller

Have a look at my last post

 

[Gryd3]

Would I need a 2-Channel receiver If I'm only using one controller?

Edit- Also, would this be a good parts list/what do I need?

Motor
Gearing
A Couple of Batteries
Brushless ESC (But not sure if it is over kill..)
Transmitter/receiver (Not sure)
And wires, soldering iron etc...

The batteries are approx 22V I think? 3.7V per cell, and those are 6 cell batteries.
That motor is 400rpm per volt, you can expect over 8000rpm, so gear accordingly to get the speed you want
I would not consider the ESC to be overkill, but it's capable of handling a lot of current! The batteries you have chosen are also very capable of putting out over 100A .. so it looks like a great start.
The motor has a max current halding capacity of 55A though, so you may want to look into keeping it safe. The current in the motor will be influences by the load on the motor and the voltage you give it. If the motor is stalled, or not yet moving, the inrush of current will be much higher. It's important to accelerate slowly to avoid a sudden surge of current through the motor when you begin to move. When I say 'slowly' I simply mean, don't go from 0% to 100% if you are at a stand-still or you will most likely hurt your motor .
As far as the channels are concerned. The # of channels on a receiver/sender are usually the amount of outputs it has.. not the number of radios.
I think 2-Channel is the smallest you can get, as it typically covers speed/steering. You can use one channel for your motor, and that leaves the other output for anything else... . a horn, light, etc. Just ignore the second output for now though.

Anyway, I think it all looks good to start! (You should also get a low-voltage alarm for the batteries. They don't like to go too low, and if they do, they tend to get damaged.)

 

[Doug Hill]

The batteries are approx 22V I think? 3.7V per cell, and those are 6 cell batteries.
That motor is 400rpm per volt, you can expect over 8000rpm, so gear accordingly to get the speed you want
I would not consider the ESC to be overkill, but it's capable of handling a lot of current! The batteries you have chosen are also very capable of putting out over 100A .. so it looks like a great start.
The motor has a max current halding capacity of 55A though, so you may want to look into keeping it safe. The current in the motor will be influences by the load on the motor and the voltage you give it. If the motor is stalled, or not yet moving, the inrush of current will be much higher. It's important to accelerate slowly to avoid a sudden surge of current through the motor when you begin to move. When I say 'slowly' I simply mean, don't go from 0% to 100% if you are at a stand-still or you will most likely hurt your motor .
As far as the channels are concerned. The # of channels on a receiver/sender are usually the amount of outputs it has.. not the number of radios.
I think 2-Channel is the smallest you can get, as it typically covers speed/steering. You can use one channel for your motor, and that leaves the other output for anything else... . a horn, light, etc. Just ignore the second output for now though.

Anyway, I think it all looks good to start! (You should also get a low-voltage alarm for the batteries. They don't like to go too low, and if they do, they tend to get damaged.)

Neat, I was not expecting that sort of reply! Thank you so Much, So Ill add a low voltage alarm, Should I run the batteries in parallel or Singular to get a longer range? And do you know of any smaller RC Controllers and receivers?
Tomorrow I will go to a Home Improvement Store and grab some thin ply and wood glue then I will go internet shopping ^-^ Thanks again

 

[Gryd3]

Neat, I was not expecting that sort of reply! Thank you so Much, So Ill add a low voltage alarm, Should I run the batteries in parallel or Singular to get a longer range? And do you know of any smaller RC Controllers and receivers?
Tomorrow I will go to a Home Improvement Store and grab some thin ply and wood glue then I will go internet shopping ^-^ Thanks again

I'm not aware of smaller controllers unfortunately... you will need to keep your eyes open. I think the ideal type for you would be the 'gun' type of controller that you can hold in one hand though. It looks like you already went that route. If you want smaller, you may have to use those cheaper Sender/receiver pairs for arduino or other microcontrollers or take-apart/modify an existing controller.
As far as batteries are concerned, here are some tips for you. I'm sure you already know many, but I'll cover it anyway to be thorough:
- Batteries in series increase voltage by summing the voltages of all batteries. Bad idea here... your motor is rated to handle ~33V max, each of your batteries are approx 22V. (44V to the motor is asking for trouble)
- Batteries in parallel increase 'current' output capacity of the pack, as well as the overall 'mAh' capacity. Great care should be taken to connect the batteries *only* when they are at the *same charge*! If you connect a 22V battery to a slightly used battery running at 20V, the higher voltage battery will feed backwards into the lower voltage battery! The difference in voltage can allow very high current to flow out of one cell and into another. This is bad in two cases... the output limit of the higher battery may be exceeded, and the charging current of the lower battery may be exceeded. Both cases can cause damage to the battery. So please make sure you fully charge and test the batteries before connecting them in parallel . This would be the easiest method to increase range/capacity. Alternatively, you can always either carry a spare, or connect the batteries to a heavy duty switch to allow you to select battery A or battery B. You can also use a 'Diode' on the output of each battery to prevent them from back-feeding into each other, but you will need a very capable diode, as the current output from those batteries will be quite high. (55Amps based on the motor specs, but may be higher... that means the diode would need to be rated at least 40W which would get very hot!)
It's up to you how you want to use the batteries. As long as you don't blindly grab and connect batteries of unknown charge in parallel, you will be fine. Just use your head and measure them first if you are unsure

*Additional battery information.
You will need a charger for your batteries that offer 'cell balancing' for at least 6 cells to charge your battery. The balancing feature will ensure that all 6 cells in the battery pack are charged properly. This pack has cells connected internally in *series*. This is how it reaches the 22V mark, but this also means the cells may develop an uneven charge if they are not balanced. This can cause individual cells in the pack to fail.
When you connect batteries (or packs) in parallel, the voltage will be the same across both batteries (or packs) . This has an added benefit of charging / discharging them evenly. You do not need to balance batteries or packs in parallel because they do it themselves Although, you must only connect identical or very similar batteries in parallel. I discussed making sure they are charged equally above, but they should also both be capable of the same output. If you connect two 5000mAh, 100A batteries in parallel, it's the same as using a single 10,000mAh battery that is close to being able to put out 200A . In reality this capability will be a little lower. If you connect a weaker battery, perhaps only capable of 50A in parallel, you may find that you stress our the less capable battery.

Anway. I hope this helps you too. Please ask if you have further questions!

(I would suggest getting a couple different sizes of gears so you can experiment with different gearing. Lower gearing will give the wheels much more torque and you a lower speed. Your motor will of course run faster.
Higher gearing will give you more speed, but this requires more torque to be put out by your motor. This requires more current and will also add to the heat of the motor.
When you first build your device, monitor the temperature of the motor. Hot is not good, and may require gearing down or putting a fan and/or heat-sink on the motor to keep it cooler.)

 

[Doug Hill]

I'm not aware of smaller controllers unfortunately... you will need to keep your eyes open. I think the ideal type for you would be the 'gun' type of controller that you can hold in one hand though. It looks like you already went that route. If you want smaller, you may have to use those cheaper Sender/receiver pairs for arduino or other microcontrollers or take-apart/modify an existing controller.
As far as batteries are concerned, here are some tips for you. I'm sure you already know many, but I'll cover it anyway to be thorough:
- Batteries in series increase voltage by summing the voltages of all batteries. Bad idea here... your motor is rated to handle ~33V max, each of your batteries are approx 22V. (44V to the motor is asking for trouble)
- Batteries in parallel increase 'current' output capacity of the pack, as well as the overall 'mAh' capacity. Great care should be taken to connect the batteries *only* when they are at the *same charge*! If you connect a 22V battery to a slightly used battery running at 20V, the higher voltage battery will feed backwards into the lower voltage battery! The difference in voltage can allow very high current to flow out of one cell and into another. This is bad in two cases... the output limit of the higher battery may be exceeded, and the charging current of the lower battery may be exceeded. Both cases can cause damage to the battery. So please make sure you fully charge and test the batteries before connecting them in parallel . This would be the easiest method to increase range/capacity. Alternatively, you can always either carry a spare, or connect the batteries to a heavy duty switch to allow you to select battery A or battery B. You can also use a 'Diode' on the output of each battery to prevent them from back-feeding into each other, but you will need a very capable diode, as the current output from those batteries will be quite high. (55Amps based on the motor specs, but may be higher... that means the diode would need to be rated at least 40W which would get very hot!)
It's up to you how you want to use the batteries. As long as you don't blindly grab and connect batteries of unknown charge in parallel, you will be fine. Just use your head and measure them first if you are unsure

*Additional battery information.
You will need a charger for your batteries that offer 'cell balancing' for at least 6 cells to charge your battery. The balancing feature will ensure that all 6 cells in the battery pack are charged properly. This pack has cells connected internally in *series*. This is how it reaches the 22V mark, but this also means the cells may develop an uneven charge if they are not balanced. This can cause individual cells in the pack to fail.
When you connect batteries (or packs) in parallel, the voltage will be the same across both batteries (or packs) . This has an added benefit of charging / discharging them evenly. You do not need to balance batteries or packs in parallel because they do it themselves Although, you must only connect identical or very similar batteries in parallel. I discussed making sure they are charged equally above, but they should also both be capable of the same output. If you connect two 5000mAh, 100A batteries in parallel, it's the same as using a single 10,000mAh battery that is close to being able to put out 200A . In reality this capability will be a little lower. If you connect a weaker battery, perhaps only capable of 50A in parallel, you may find that you stress our the less capable battery.

Anway. I hope this helps you too. Please ask if you have further questions!

(I would suggest getting a couple different sizes of gears so you can experiment with different gearing. Lower gearing will give the wheels much more torque and you a lower speed. Your motor will of course run faster.
Higher gearing will give you more speed, but this requires more torque to be put out by your motor. This requires more current and will also add to the heat of the motor.
When you first build your device, monitor the temperature of the motor. Hot is not good, and may require gearing down or putting a fan and/or heat-sink on the motor to keep it cooler.)

WOW! So smart

I will get different size gears, I will probably mount the batteries in aluminium boxes to act as a passive heat sink, I will watch how hot the motor gets, And if it comes to it, I will put a heat sink on or Ill add a small fan or something like that..
Although, I may do it separately with a big switch between, It seems easier but would add a bit of deadweight sometimes..

If I run them in parallel, Do I just buy the one charger?

Thanks soooooo Much!! So helpful!

 

[Gryd3]

WOW! So smart

I will get different size gears, I will probably mount the batteries in aluminium boxes to act as a passive heat sink, I will watch how hot the motor gets, And if it comes to it, I will put a heat sink on or Ill add a small fan or something like that..
Although, I may do it separately with a big switch between, It seems easier but would add a bit of deadweight sometimes..

If I run them in parallel, Do I just buy the one charger?

Thanks soooooo Much!! So helpful!

The batteries will not be permanently wired in parallel. At least one charger is needed.
You would essentially just have a Y-Cable on the longboard that lets you connect more than one battery. When done, the batteries are removed and charged individually.
The charger and batteries you have will have the power terminals and 'sense' wires used to balance the cells inside them. The sense wires are ignored while you use them, but must be used when you charge them.
I'm sure it's possible to charge them in parallel as well, but I admit to not knowing exactly how the sense wires are connected internally, so I can't suggest the modifications required to actually do so.
The amount of chargers you use is entirely up to you . You can have 1 or 9, just so long as you charge each battery individually.