now i am currently building my own rc car, and it is for my major project for year 12 d&t. i need to make it solar powered, and i am machining my own chassis and parts, but i need some help with the electronics. i need to know how to control the speed of the motor, whether i should use brushless, and if i should put a battery in there and charge it from the solar panel just to make it run a bit longer. any advive would be good, as i have no idea.

You basically have 2 choices:

1: You can make the car run off 100% solar with no battery. This choice is advisable as i think it will be favored more by the D&T markers.

This would require the need for a custom maximizer, with built in RC connection to control the output voltage for speed control. I can build this for you easily . If you do run this setup, i would advise you use a minimum of 12 watts of solar power, and also use that 4.5v Maxon you got. That would be an excellent power setup with high efficiency.

You wont be able to run a brushless motor off straight solar because the power requirements are too high, and there is too much energy taken in the speed controller/RC gear as well. So the negatives outweigh the benefits. A straight solar/brushless setup i would only recommend if you had a minimum of 30watts of solar energy.

2: You can have an inboard battery/solar system.

With this setup, the battery will act like a fuel tank, and can provide the power required by the BL setup and RC gear during peak loads, and the solar panel will recharge during light loads.

Whichever way you choose, ill be there to help out.

Soo...

How you going with this??

Well, i have built a prototype and the thing looks good. i've decided to use 16 DS panels, which will give me about 10 watts but only weigh about 400g. i will start to build the actual thing within the next week or two, so it should be finished in the next month. i have also decided to get rid of all the suspension and rubish i was going to put on it, because it wasnt going to have enough power for what it was going to weigh unless i put a battery in there, which would only complicate things. i reckon that in the end it should weigh about 1kg - 1.5kg so 10 watts sounds good to me

okay, now there have been a few changes, as the panels that i wanted to use are discontinued, so im using 8 hexagonal DSE panel, bout 8-9 watts. Hey tony, how long will it take for u to make a speedy/maximiser, cause i will probably need it within the next month or two if possible. It can be a modified red maximinser or something if you want - as long as it works!!

Itll take me a few solid days. Ill look into it as soon as uni is over.

thanks tony!

Time for an update Predator1. Not long now until the MDP is due in.

okay, its ready to be built, i have all the cad stuff done so it will only take one day now...other than the electronics...

cough##howsthespeedygoingtony##cough

catch my drift???

hey tony,

im going to build this thing before the end of next week so i can test it and stuff..

when can you build a speedy by cause ill need it pretty soon..

Thanks Tony...

I need to know the open circuit voltage on your panels.
and do you want forward and reverse?? or we keep it simple forward and brake??

Progress here

u seem to have figured this out by urself, but yeak - keep it simple, no reverse, and only about 16 volts open circuit cos im using 8 DSE hex panels, which gives about 8-9 watts

Can you please post some pictures up to show us the progress your making with the car?

http://www.rctech.net/forum/web-links/2 ... ost4570827

I just completed my solar car. I built the car to the Solar R/C Cup rules. If you have any questions you can email me

trailranger (at) yahoo (d0t) com

Some youtube vids too at

http://www.youtube.com/beartracksracing

This is where I first learned of Solar R/C Cup. My goal is to get an events going for April ~ August in the U.S.
http://groups.yahoo.com/group/solar-RC- ... =101986928

Thats awsome and cars look cool as well. Do you guys use mppt's or maximisers in the car??

No MPPPT's, I have no idea where to find a such a device.

I did just buy a DC-DC convertor to step down or up the voltage. The plan was to use the convertor in hard start situations via a 3rd channel on the radio. Once the car is rolling smoothly, DC-DC is removed from the circut and the motor sees the full voltage of the panel. On second thought after I bought the DC-DC convertor I could not think of a practical arrangement without wasting current.

This arrangement should allow me to gear beyond the static stall point of the motor with the supplied current.

Over here in Aus we use solar maximisers, these ones http://dreamtec-rc.com/product_info.php/cPath/24/products_id/48 basically it acts like an electronic gearbox, and gives your motor more amps during acceleration and more volts as it speeds up.

Every car in Australian competition uses these because they give you up to 50% more power. Its a DC-DC converter but i knows where your solar panels maximum power point is, and holds it there, switching the output voltage and current to match the load.

This can be connected directly to a normal rc car ESC.

Thought ill put this picture up because the lineup looks cool

OMG.....gimmie gimmie gimmie....I'll stop drooling over the MPPPT.

I do have one question before I make my car $100 more expensive. The output volatage is 2V ~ Voc and the input is 10V.

My solar panel is 9.9Voc, is this device compatible with my setup?