Volta Solar Racer

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zackboston
 
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Volta Solar Racer

Post by zackboston »

I purchased one to see if we could use them in our Learn 2 Teach, Teach 2 Learn Program this summer. Well, I've tried angling the motor and wheel and put it out in full sun, but it moves maybe 1/2" a second. Any hints? The children are not going to be impressed by this! smile. But maybe I am doing something wrong. . .

thanks for any help you can give.

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adafruit_support_bill
 
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Re: Volta Solar Racer

Post by adafruit_support_bill »

Check that all the moving parts spin freely. Make sure nothing is binding or causing undue friction.

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zackboston
 
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Re: Volta Solar Racer

Post by zackboston »

I just wanted to update you that we got our Volta flying. Your advice was helpful. Here are the two problems my youth teachers and I made, both of them caused friction and slowed down the car:

1) The biggest thing was when we discovered how the gravity helps the wheel cam --- we did not tilt the wheel right initially and had the cam arm sitting right on the wheel when the car was held up in the air, which was causing too much friction once we set it down. Once we adjusted the cam arm so it was 1/8" from the wheel before we set it down on the ground, it flew!

2) The other problem was adjusting one of the hubs that connect the wheel. We had them too secure (this is an instance where a little looseness helps a lot!) and again that caused friction. When we loosened the connection, again, the Volta really took off even faster so you had to walk at a really fast clip to keep up.

We love our Volta at the South End Technology Center @ Tent City! When we finally got it working and were testing it out on the sidewalks in the housing development, it was like a pied piper. . . children and adults from the street and stoops came down and wanted to see it and know more. Thanks for all your help.

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adafruit_support_bill
 
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Re: Volta Solar Racer

Post by adafruit_support_bill »

Great! Thanks for posting your results. Next time I'm in the Back Bay, I'll have to stop in and see it run.

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benintucson
 
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Re: Volta Solar Racer

Post by benintucson »

Hi . . .

I've been the happy owner of a Volta Racer for several years now (I got mine directly from the manufacturer, but I'm happy to see that Adafruit also sells them) . . .

https://www.adafruit.com/product/1527

Whenever I'm displaying my full sized electric car - a Mitsubishi i-MiEV - at an event, the Racer - more often than not - also comes along. It's a great educational tool to explain concepts of solar energy and sustainable electric transportation. The PV panel is very sensitive and, here in the Arizona sun, it's hard not to have the toy car zipping around in circles to the delight and amazement of all . . . especially children.

While it's promoted as a "batteries not needed" toy, I've often thought it would be great if the panel was paired with a simple lightweight charge controller and tiny lithium battery. A Volta Racer modified in this way could become a self-perpetuating device . . . one that can be charged exclusively from the Sun, yet operate even when the clouds come out or people crowd around it, obscuring the panel with shadows. The panel would keep it going and top off the battery when it's sunny. The battery would keep it going when it's not. Or, that's the desired effect.

I see this Adafruit product and it's looks like it might work for what I describe . . .

https://www.adafruit.com/products/390

. . . when paired with a tiny battery, like this one . . .

https://www.adafruit.com/products/1317

Concerns I have, though, is if the Volta Racer's panel outputs enough voltage (I think it's rated at 5V maximum) to get the Adafruit controller working and if the "load" output of the controller can be padded down sufficiently to keep the very sensitive electric motor spinning at about the same (rather low) rpm it would be experiencing when operating off just the unadorned PV panel.

Just as an experiment, I recently hooked up a 10 Farad / 3V supercapacitor to my Volts Racer's motor and the little car zipped across the living floor at about twice the speed it would have with the panel out in the Sun. So, we're talking diminutive voltages here and minimal battery sizes required.

Any advice or observations is appreciated. Thanks in advance . . .

Benjamin Nead

http://tucsonelectricvehicle.org/

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adafruit_support_bill
 
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Re: Volta Solar Racer

Post by adafruit_support_bill »

Thanks for the feedback. With ~5v from the panel, the #390 solar charger can charge the battery. It does a pretty good job of scavanging power in marginal solar conditions.

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benintucson
 
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Re: Volta Solar Racer

Post by benintucson »

OK. Thanks for the info, Bill. Looks like it's time to buy one of these boards and a few batteries to start experimenting.

I assume the Volta Racer's little PV panel doesn't have a blocking diode. Will I need to configure one when using the #390?

Also . . . what's the most effective way to lower the voltage on the load output? I haven't measured anything yet, but I'm assuming that the Volta Racer's motor want to see
something like 1.2V or less.

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adafruit_support_bill
 
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Re: Volta Solar Racer

Post by adafruit_support_bill »

The 390 has a blocking diode built-in. Not sure what the motors are rated for. But small brushed DC motor ratings are generally pretty flexible. In theory, over-volting by 2x will shorten the lifetime of the motor, but it will still probably outlast the car. We carry a 3.3v DC/DC 'buck' converter. You can find lower voltage buck converters on-line.

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