Let's Make Robots!

Solar Trike

Much thanks to D&G Green Products for their support http://www.dggreenproducts.com/



My team and I are building a solar powered trike for a solar innovation contest. I do not have much information as of now, but i did pick up the solar panels today. I am still working out the finer details. I know i will need some lead acid batteries, a motor, a trike, speed control,  and a charging circuit. If you have any advice, feel free to leave it in a comment :) No i dont get to keep the solar panels, they are the school's :(









UPDATE 11.27.10

I went driving around town looking for an adult tricycle to buy. Well i found a store that sells tricycles but they were a bit steep for a school project budget, but the goldmine i hit was the owner of this store. His whole house runs on solar power, he has made many electric trikes before, he has all the components to do exactly what i need. He is basically an expert in this. I lucked out finding such a person in my town. 

He led me to his back storage where he was able to sell me a scooter which has most of the parts we need for $30. 


The scooter didnt have a chance...


What i needed from it was its control box...




...key switch...


... 36v motor...



and maybe chain and sprocket 



The batteries are shot


The throttle, key switch ( I left the keys at the guys shop), motor, and batteries plug into the control box. This will read the throttle and control the speed of the motor. Easy enough.

I still need to acquire a trike, batteries, and a charging circuit. The last 2 i can get from the guy. Then the building can really begin.



Maybe next year we will do a solar powered unicycle ;)




Update 1.23.11

Well the trike is running on electricity! 

"wait, the last update was when you took apart the scooter and now you have an electric trike?" YES!

The biggest hassle was not building it, that only took 2 days. The hardest part was finding a cheap tricycle, that took months.

The whole thing was basically built with those scooter parts which is pretty cool i think. Motor, chain, sprocket, motor mount, throttle, key switch, and speed controller came from that scooter. The batteries came from another scooter also.

Sorry no real construction photos because like I said, it was built extremely fast. 

The hardest part of the build was the motor mount. The best place to put it was in the back so the chain did not have to be broken (It had no master link). The chain and sprocket is from the scooter since it was made to fit the motor.

You can still pedal the bike also, due to some fancy bike part that I do not know the name of. It is the thing that the sprocket is bolted to and that slips on the axel. (seen below) Basically when the motor is spinning, it spins the sprocket and the axel making the tires move. When you are pedaling, that magical bike part free spins and does not spin the motor's shaft. 


The trike has a shifter on the right handle bar because this is a 3 speed. I did not want to tamper with that so i put the right hand throttle on the left handle bar ( I am a lefty anyway)


Everything else goes in the basket.

you have the key switch

The controller

The batteries costs $5 for all three. They are old but have been de-sulfated so it was a very good deal considering new ones are $40 a piece. They are 12v 12AH and are wired in series.


So there you have it for now. It runs good. Next I need to add the solar panels.



UPDATE 2.13.11

I have the solar chargers now. I bought 3 of them, one for each battery. Next i have to make a cart for the solar panels to sit on and be pulled behind the trike. I will have to change some of the wiring but that should be easy. 


Update 2.14.11

The cart is almost done. 

We had a $20 trike we bought laying around so we figured the back end was good enough to use as the cart. Sorry no photos before it was ripped in half and painted, you can imagine...


The tires where garbage


So with support from the same local bike shop, we had all new wheels, tires, and a shaft lended to us for the project. We shouldnt need the cart after we give the solar panels back, unless some one wants to donate solar panels :). 

So in the end, with a shiny coat of paint you have this

Wheels still have the price tag on them


Next the trike has to be hitched to the trike, but here is an idea of what it will look like. Bars will run across the cart to hold the solar panels. 


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We made one at school. Different design but you seem to have the basics there...nice. Make sure u got good breaks and steering that was a problem we had.

It's called a freewheel. Mechanically speaking, a form of ratchet.

Is that axle one piece? Or do the wheels turn individually? Differential of more freewheels?

Ah free wheel.

It is a one piece axle, but only 1 wheel is the drive wheel. The other is just connected to a bearing and spins freely. 

My mate and I once built a trike, powered by a moped motor. The axle was stiff and one piece. The tyres were monsters. As a result, it was impossible to turn the trike. Even without power from the motor.

oetkar 1992

So we cut the axle and powered only one wheel: the left one. They were very far apart. This new configuration would turn very easily. To the right! The driver had to constantly compensate and would develop muscle aches in his steering arm. Turning right was simply done by giving more power on the throttle and less resistance on the steering handle. Turning left at speed was pretty much impossible. Balancing the whole contraption was a challenge, despite its width.

Ohhh, 1992 was a good year for hacking mopeds, 2CV's and anonymous agricultural vehicles. 8-)

Oh right, lessons learned: 1x3 driven trikes are fun. Do as I say, not as I did: put pressure on the front wheel. Place the rear wheels close together. Use narrow tyres. Don't use an 80 cc Puch Sport with special carburettor as your power plant. Build a steering handle that you grip with both hands. And most of all: have fun!

Oh right, you're doing all that. Good for you. Fun story to tell anyways!

Very impressive performance, well done.

Good find on the parts, and its always good to have local support.

I'm curious if he mentioned how long those batteries (12v/ea?) worked for him.  those are probably $15-20/ea.   im guessing a deep cell marine battery would be better if this was something you were going to keep going.  but, sounds like it will get ripped apart after the competition is over, or do you intend on keeping it going without the panels.

do you have a model # on the motor, or an amps rating?    wired in series (36v), those panels will drive that motor all day in the sun, if the motor consumes 5 amps or less.   but, and its a big but, 36v of panels wont charge 36v of battery.   so the panels will do 1 or the other.

I suppose you could have 2 switches, 1 to run the panels in series (36v @ 5a) to the motor circuit, and the other switch to run the panels in parallel (18v @ 10a) to charge the 3  12v batteries in parallel.     That would be some fancy wiring, but if anyone can do it, you sure could.      And if you turned on both switches at the same time, you would very likely create a black hole in the universe.   or at minimum, it would make exciting footage for a video.


Don't forget a differential!

Just dumping a wild idea on the table here.

Would it be possible (possible first: practical later please). Would it be possible to rig your two panels with DPDT relays, so that your MCU could choose for a series vs parallel configuration?

When the 2 panels in series produce more than double the voltage required to charge your batteries, switch to parallel. And vice versa.

Would it make the rig more efficient? Or rather more versatile for different wheather conditions?

Rik, I don't know enough about DPDT relays to say if it's possible or practical, but I found solar panels work like this: - no light = no volts, no amps - low light = fully rated volts, and very low amps - medium light = fully rated volts, medium amps - bright light = fully rated volts, fully rated amps (or over-rated amps) In other words, it's easy to get rated volts, but maximum amps are achieved only when in bright sun light. Even better when pointing directly at the sun. Clouds passing over head won't change volts, just amps. Have you ever tried your idea with batteries? I think similar results would occur with solar panels.

That means you never have to step down the voltage to battery level. Which I was afraid of. That's solving a non existing problem then.

Just choose you battery voltage and connect your panels as required.