Need motor help with Electric Power Brush project for clearing snow

[german_cargo]

I'm in the snow removal business and am unhappy with my snow plow on residential driveways. I am going to fabricate a light duty power brush for my vehicle, and I am going to power it with an electric motor and battery pack for quiet operation and relative simplicity.

The demands on this power brush will be quite small. Most of my houses have two or three car width driveways no more than 50 feet long. It'll only be used when there is less than 2 inches of snow on the ground. When I use my blade, I go up and back about 4 times, working my way across the driveway. The blade is down for less than a minute, and then it takes about 5 - 10 minutes to clear the walk and tidy up, and then it's another 1-5 minutes to drive to the next house.

So the motor will be operating in about 1 to 5 minute stretches with a 5 to 10 minute break in between.

From what I've gathered, I will need something in between the power of an e-bike motor and a golf cart motor (probably closer to that of a golf cart). The walk behind style power brush snow blowers you see on the market spin at about 280 RPM. My brush will be twice as wide, and I'll want it to spin closer to 650 RPM.

I'm thinking a 36 volt DC brushless system is what I'm looking for, but I don't know how many watts would be appropriate. Golf Cart motors are rated using horsepower figures so I'm not sure what that translates to. I should also note that an actual golf cart motor is not what I'm looking for -- I'm looking for a simple chain driven set up, and golf cart motors have splined shafts.

I'm assuming a standard golf cart battery pack will last me for my 53 house route. Apparently they're typically good for 25-40 miles in a cart.

In terms of control, I don't need a throttle. I only need one speed and the ability to make it spin both directions.

Any motor and battery specs any of you could suggest would be greatly appreciated!

 

[Tom.G]

Just to give a ballpark figure, find the closest rated commercially available one. Then find the ratio of changes for your desired design.
For instance you want the brush twice as wide so the first multiplier would be 2.

• (brush width)_DESIRED / (brush width)_COMMERCIAL = 2
• (brush speed)_DESIRED / (brush speed)_COMMERCIAL =650/280 = 2.3
• (brush diameter)_DESIRED / (brush diameter)_COMMERCIAL = xx
• (travel speed)_DESIRED / (travel speed)_COMMERCIAL = yy

Then multiply all the scaling factors: 2⋅2.3⋅xx⋅yy = 4.6⋅xx⋅yy = ?
Now multiply the COMMERCIAL HP. by the Scaling Factor above. This gives you an approximate HP. needed.
Finally, multiply the HP by 746 to find Watts for the motor.

Batteries are usually rated by Volts and Amp-Hours. If you divide the Watts by the Volts you will find the Amps drawn from the battery.
Multiply the battery Amps by the runtime you want to find the battery Amp-Hours needed.
However, batteries do not like to be discharged all the way to zero, they die rather rapidly that way. So multiply the battery Amp-Hour requirement by two or more.

You may decide that it is not commercially viable to build-your-own.

It does sound like an interesting project though!

Please keep us updated on your findings/progress.

Cheers,
Tom

 

[jim hardy]

...

I am going to fabricate a light duty power brush for my vehicle,

Will this be attached to your vehicle, sort of like a snowplow but with a rotary brush not a blade?
If so,
I'd think about the starter motor from a car or light truck engine , powered from the vehicle , .
Farm supply stores like Tractor Supply carry an assortment of sprockets...

 

[CWatters]

Google suggests we are talking anywhere up to 13HP. I'd look at some sort of mount for a commercial gas powered brush.

 

[oz93666]

Have a look on eBay ... a vast array of brushless motors at low prices used for RC .. up to many KW in power (1HP=750W)

The 'KV' number indicates how fast ... lower KV lower RPM

 

[german_cargo]

Need motor help with Electric Power Brush project

Yes it’s going on the front of my vehicle like a plow.

I’ve considered a car engine starter, but I’m not sure if it’s over kill and if the speed would be right. It might end up being the most cost effective solution, though.

How would I find out how much friction is generated by a power brush? Obviously the end goal in that would be finding out the amount of torque needed to spin this thing on the ground. It’s important to note that when the brush is lowered to the ground, it will be sitting on a pair of castors rather than being pressed into the ground. I plan to have it set up so that there is only a couple cm of deflection of the bristles where they contact the ground. Like I said, this is a light duty set up.

Its very hard to believe this thing needs much power but all the power brushes on the market seem so high powered. 16hp? The Volkswagen Beetle only put out around 30hp back in the 50s if I’m not mistaken. If it could go fast enough, I bet a battery powered impact gun would spin this thing on the ground if connected to the brush axle.

 

[anorlunda]

Google reveals a number of battery operated snow blowers. You could cannibalize one of those to turn a brush and mount it to your vehicle.

But on second thought, why not just mount it on your vehicle and let it operate as designed? I must assume that if the brush was more efficient than a two-stage blower, that they would have designed it that way.

 

[dlgoff]

I'd look at some sort of mount for a commercial gas powered brush.

Except that,

I am going to power it with an electric motor and battery pack for quiet operation

bold by me

 

[jim hardy]

I’ve considered a car engine starter, but I’m not sure if it’s over kill and if the speed would be right. It might end up being the most cost effective solution, though.

i wondered too about the speed.
I envisioned using the flywheel too , that way you have gears that mesh and give you speed reduction.
If you find a big diameter brush you could bolt flywheel right to the end of it.

Have fun

old jim

 

[CWatters]

I suspect it's not easy to calculate the power required but we could try ballparking the numbers...

Can we assume the brush is used at an angle so it throws the snow ahead and to the side? Eg not just straight ahead or it builds up.

How wide is the brush? 1m?

How fast do you want the brush to move over the ground? Walking pace?

How deep the snow?

 

[CWatters]

You say commercial machines are 16HP. For no particular reason let's assume they actually run at only 4HP on average. That's 4*750=3000W. If you used a 24V starter and battery that would draw 125A.

If each house takes 2.5 mins ? and you have 53 houses that's a total run time of 2.5*53/60=2.2 hours. So you need two 12V batteries of at least 2.2*125= 275AH. Since lead acid batteries don't like being deep discharged it would be advisable to double that so you don't go below say 50% charge. Call it 550-600AH?

You will also need a decent charger. If you charge overnight (8 hours?) It needs to pump out at least 275AH/8H=34A

Don't rely on these numbers, make your own judgement and redo the sums. It would be easy to find out you actually need four times that capacity. For example if it actually averages 8HP and each house takes 5 mins.

 

[jim hardy]

When estimating, try a couple diverse methods and see if they reasonably agree .
Here's my first shot at your power needs -

How hard does a snowblower push back against you as it throws the snow away ? Ten or twenty pounds of force?
A two foot brush (1 ft diameter) will need about that much torque in ft/lbs

My brush...I'll want it to spin closer to 650 RPM.

650 RPM is 2042/π , if we choose that for our RPM and plug into the horsepower formula

$HP = \frac{2\pi X Torque X RPM}{33,000}$

i get $HP = \frac{2\pi X 20 X \frac{2042}{\pi}}{33,000} = 2.48 hp$
(i love it when π's cancel out)
half that if ten pounds is the thrust.

And at 12 volts it takes about 62 amps to make a horsepower ($\frac{746 Watts}{12Volts} = 62.2Amps$)
So it'd pull around 80 to 160 amps from a car electric system.

So the motor will be operating in about 1 to 5 minute stretches with a 5 to 10 minute break in between.

5 minutes seems to me a long cycle at 160 amps... but probably not at half that current.
I have a huge diesel engine starter from my favorite salvage yard that would laugh at that service... do you have a good junkyard nearby ?

Worth some experimenting ?

old jim