# Solar powered motor

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#### picbits

##### Well-Known Member
Is it to power the go kart straight from the sun or is to to charge batteries which will then power the motor ? How much sun do you get where you are ?

#### xandervdm

##### New Member
It will charge batteries while driving. And there is an average amount of sun.

#### picbits

##### Well-Known Member
So you have a 250w motor, find some solar panels that will provide 250w at 24v with an average amount of sun plus the wattage you require to charge whatever batteries you may be charging (7ah ? 70ah ? 700ah ?) in whatever time you require them recharging in plus whatever losses you will incur with speed control of the motor and charging of the batteries.

#### xandervdm

##### New Member
Do you know how I can calculate the time it takes to charge a battery?

#### picbits

##### Well-Known Member
battery capacity * charge rate - losses is usually good place to start.

What kind of battery technology are you using ? What kind of charger are you going to hook up to the solar panel ? What kind of controller are you going to use to control the speed of the motor ? What level of background have you got in electronics ?

You have given us very little information to go on here other than a single link to a motor.

#### MikeMl

##### Well-Known Member
Methinks that the required area for solar panels would make a fine roof for a garage capable of housing my Piper aircraft.

#### picbits

##### Well-Known Member
So a quick bit of research on eBay shows that a solar panel that can generate around 250 watts (in ideal conditions) measures the following :

1640 x 992 x 40 mm

That would be just to power the motor with no other capacity available to charge the batteries (assuming you were running it at full power).

#### ronsimpson

##### Well-Known Member
That would be just to power the motor with no other capacity available to charge the batteries (assuming you were running it at full power).
That assumes high noon, panel tipped to face the sun, no clouds, high altitude, 0% humidity, and every condition at its best.
Has any one ever got 250 watts out of a 250W panel? Maybe 200W.

#### xandervdm

##### New Member
Alright so it's best to buy a solar panel that is about 500 watts just to be sure?

#### xandervdm

##### New Member
battery capacity * charge rate - losses is usually good place to start.

What kind of battery technology are you using ? What kind of charger are you going to hook up to the solar panel ? What kind of controller are you going to use to control the speed of the motor ? What level of background have you got in electronics ?

You have given us very little information to go on here other than a single link to a motor.
I'm thinking of a lead acid battery, I didnt think about a charger nor a controller yet and I don't really have any background in electronics,

#### picbits

##### Well-Known Member
Alright so it's best to buy a solar panel that is about 500 watts just to be sure?
You'll struggle to cart round a solar panel on your scooter that is 1.6m by 2m weighing around 35kg ......

#### xandervdm

##### New Member
That's true but is there an alternative?

#### picbits

##### Well-Known Member
That's true but is there an alternative?
What exactly are you after doing ?

#### xandervdm

##### New Member
do you mean when the project is finished?

#### picbits

##### Well-Known Member
Yes - what is the aim of your project ? What is your budget? What is your estimated maximum speed / distance traveled / time between charges etc ?

Is this a personal project / college project / professional product ?

Have you got an idea for the design of the kart / calculated the aerodynamics / drag etc and worked out what kind of power you're going to need to consume for a constant velocity ?

Your solar panels are going to cost you potentially $500-$1000 as well as the batteries for storage, controllers etc.

If you are only going to be traveling a few miles each day then consider just using batteries and charging the go kart from your home electrics or a solar array mounted on your property.

To power the kart by solar on a budget is not going to be easily achievable.

#### Beau Schwabe

##### Active Member
I did some contract work a few years back for a friend of mine that had connections to the solar car race. After I was done doing the work, he asked how I wanted to be paid. Off the cuff, I said "how about in solar panels" ... So I ended up with ten 240Watt 24V solar panels. I mention this because I have similar motors that I use with the solar panels to drive a few fans in my barn. For what the OP is wanting to do, he will want at least two panels. (Sorry mine are not for sale) ... As mentioned 500 Watts is about right.... You want to figure immediate power requirements, and charging power requirements .... so if the motor is rated so that it matches one of the solar panels, then the additional solar should be the rate at which you can charge the batteries. 5 to 10 Amps is probably a good charging rate, and at 24V that's 120Watts to 240Watts of overhead that you will need to charge and ride at the same time.

#### xandervdm

##### New Member
Yes - what is the aim of your project ? What is your budget? What is your estimated maximum speed / distance traveled / time between charges etc ?

Is this a personal project / college project / professional product ?

Have you got an idea for the design of the kart / calculated the aerodynamics / drag etc and worked out what kind of power you're going to need to consume for a constant velocity ?

Your solar panels are going to cost you potentially $500-$1000 as well as the batteries for storage, controllers etc.

If you are only going to be traveling a few miles each day then consider just using batteries and charging the go kart from your home electrics or a solar array mounted on your property.

To power the kart by solar on a budget is not going to be easily achievable.
It's a school project, the maximum speed should be about 8 miles per hour, our budget is something around \$2000.

The goal is to make a kart that can drive really long (a couple of hours), the sun should give more power then the motor uses.

#### picbits

##### Well-Known Member
Beau above has given you some excellent advice based on real life experience. A 250w motor isn't very powerful so be careful with your aerodynamics and weight or consider using two motors - they will take a current/power proportional to the load put on them so running two motors at a vehicle speed of 8mph will not be that much more power consumption than running one of them.

Maybe try it with one, keep the fact that you might need a second motor in the back of your mind and design your kart with the option of a second motor.

I work in the automotive industry and we've seen some interesting stuff through our doors including a design by one of the world leading designers in motor technology - fascinating bloke.

A 250w 24v motor run from 2 x 12AH 12V batteries will run for approximately an hour but pick your batteries carefully as a lot of the lead acid batteries don't like being discharged too much.

If your course is nice and flat, your weight isn't as much of a hindrance as if you have lots of slopes. Once you get up to speed, your only major power drains are your rolling resistance and air resistance. If your course is not flat, consider using some kind of energy recovery system in your controller design.

Good luck

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