Motorized book cart

[aishah]

Hi everyone,
I am trying to build my electric book cart as this example.

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My limit is in mechanical structure, how to choose motor, wheel and casters dimension,battery,charger,integration of motor to wheel.

From my opinion and some info, I have survey :
1. Motor and Controler

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24VDC,100W, gear ratio:100
driver control come with I/O port that can connected to joystick.

2. caster and wheel

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10" solid wheel with 5" casters.

it is enough spec to build the book cart?
Can anyone give some link that i can read or any suggestion?
I keep stuck how can I assemble motor with the wheel?

Please help. Thanks

 

[RobertD]

holy heck, that is super crazy and cool, assuming, of course, this isn't some weird spam. Why do you want to make a book cart?

 

[Doc Sprocket]

Speed reading.

 

[Poboy kartman]

Speed reading.

 

[mckutzy]

Hello and welcome...
Id be thinking something from a motorized wheel chair. Only one motor is needed, and a simple forward/reverse switch. Typically most are 12v so batteries are plentiful, as per size, maybe something like a motorcycle/scooter battery size.
I would suggest some kind of a manual disconnect from drive, encase your batteries die on you, you will be able to move it with out the drive connected.

 

[aishah]

Hello and welcome...
Id be thinking something from a motorized wheel chair. Only one motor is needed, and a simple forward/reverse switch. Typically most are 12v so batteries are plentiful, as per size, maybe something like a motorcycle/scooter battery size.
I would suggest some kind of a manual disconnect from drive, encase your batteries die on you, you will be able to move it with out the drive connected.

hello everyone,

My purpose is to make easy to school library to handle book when it walking on the ramp.

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as mckutzy mention, I would be able to move using motor or if the insufficient battery it can work manually.

Mckutzy: can I know the type of battery that I can use? It is lead asid? and how to choose the AH?

 

[Poboy kartman]

How much are you going to use this? Is this something you are going to use all day or just once in awhile? What kind of weight will you be trying to move?

I get the feeling you just want a power assit to handle a 30° incline- so if all you need is to equalize that to the same effort as pushing on level ground you shouldn't need a whole lot of motor or battery.....

Don't know though- electrical isn't really my thing.....

 

[mckutzy]

I'm not exactly sure myself, I know the expert, I think the name sid comes to mind.

I would say that knowing a motorized wheel chair can haul 2-300lbs no prob up a ramp with ease, that maybe that might be the way. I'm not too sure of your location in the world has these available readily. But something of this caliber of machine I believe is your best bet.

 

[itsid]

First, I don't think a 100W motor will get you moving.
Books are heavy beasts.

So what you're want to move is about 300kg in the end (kart, batteries, motor... plus books of course)

Let's assume that's a 10° inclination of your ramp,
since I believe it's made intentionally for wheelchairs,
it'll not be more than that.

So let's find a good motor value...

F = m * g * sin alpha
m = moving mass (your kart)
g = gravitational force = 9.81m/s²
alpha = your road (ramp in this case) inclination

300 * 9.81 * sin(10) = 511.05

511.05 Newton is a serious number already, luckily you only need walking speeds

The mechanical power would be
Pm = F * v
v = speed 5km/h (1.4m/s) (~walking speed)
Pm = 511.05 N * 1.4m/s = ~715 Watts mechanical power.

A motor NOT made for electric vehicles is not rated by it's output of mechanical power,
but instead by it's draw of electrical power.
And we can assume an efficiency of about 80%..
(that is if it draws 100W it will provide only 80W mechanical power.)
And you need 715W (*10/8) that's ~895 Watts of electrical power

Sooo a 900W motor is a good starting point.

Let's say you need to actually move the cart two full hours a day,
and you don't want to reload the batteries during the day.

that's 1800Wh of capacity for your batteries

let's just stick with the 24V system for a calculation.
900W / 24V = 37.5Amps

that's either one 24V 75Ah battery, or two 12V 75Ah batteries.
two 12V lead acid batteries with 75Ah each easily weigh 50kg.
let's just assume another 10kg for the motor/controller and stuff.
I think the kart will be close to 70-75kg in the end if it's a "lightweight" structure.
So you can move 225kg of books, or let's say about 450 books with your cart.

If you need much less than that, then please let us know, or recalculate yourself

'sid