Battery + Solar = duel powered Robot

How to INTERFACE SOLAR PANEL KIT with battery operated Vex IQ robot ?
Any suggestion on which SOLAR PANEL KIT to buy ?
Aim: To demonstrate in a science fair pollution control using SOLAR + BATTERY POWERED CARS
instead of gasoline. Txs

Sounds like a very cool project!

Sadly, you need the battery pack to run the brain, and there isn’t a good way for you to hook up an external power supply like your solar cells to it.

If you Google solar toy car build, you’ll find some videos on how to do that. Good luck with your project!

Can you not use doawk capitalization? Its really annoying to read.

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Found one but a bit too advanced :

So the big difference is they are driving the motors directly from a battery. You can’t do that with the VEXIQ motors. If you follow along with what they are doing there is no brain.

What I was suggesting was more along these lines (

Txs Foster. Will change project to only solar power if i cannot find duel power battery + solar hybrid model.

Found : Battery + Solar = Duel Powered Car

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Very cool, you got your dual power source! Looks like it’s parts that you can find around the house. I like how they use a hot glue gun to put 90% of it together.

Do me a favor and post back to this thread on how you made out.

Good luck!

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Sure, due date for the science fair is March 2nd week so i will post a s a i am done.

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Lets do the math!

The most optimal solar panels can reach up to 200W per sq meter in direct sunlight, which is about right looking at this model this model of 330W at over 1.5 square meters. Lets assume you have a perfect 7.2 V panel to charge your batteries.

Now we need to figure otu the required power. Vex IQ runs at 7.2V, and according to this post consumes around 110 mA unladen, and around 500mA when operating a motor.

Using P=IV, where P is power, I is current, and V is voltage, we can tell that our robot is operating at .8 to 3.6W for a single motor. That means for a motor to drive, and a motor to steer a wagon-like setup (not tank drive), it would require around 3W of power. If you had tank drive, expect around 5w of power needed at any given time.

At 200W/m^2, that means we will need 3/200 or .015m^2 of panel. You will need 150 square centimeters, which is right about 15 cm (6 in) by 10cm(4in). or 12.2x12.2cm (4.8"x4.8")

That is doable. However if you are not in direct, straight-above sunlight, or any of your equipment is less than efficient, you will need to increase those numbers. Indoor lighting… several magnitudes more panels.

I would assume that if we needed 100% more current than expected, and our panels are only half the efficiency as stated above, you would need 12"x"8" of solar panels in outdoor lighting, and if you wanted to operate it indoors… don’t.

Additionally if you ran a battery charging circuit and hooked up to a battery, you could operate the panel at 100% all the time and just charge the batteries. That wouldnt be 100% efficient, but it would give you more charge than you would have had, and would allow your bot to run through the shade for a bit every so often.

The numbers are in your favor. Good luck!


If you wanted to tap into the battery, you might be better off using NiMH rechargeable batteries and the AA battery holder. It’ll be easier to mod than a normal battery pack:

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A somewhat good idea, the problem is that they needs to run off of solar/battery at the same time. So they need to put a charging circuit into the battery holder. While the holder and nicads are somewhat inexpensive they are up with getting a charging circuit to work. I’d be worried about trashing the brain since the panel needs to supply more than 8.2 volts to get the pack to charge. I don’t know what kind of circuit they have in the brain, since they are just expecting their stock battery pack. The full battery pack itself has overcharge protection built into it, but most of the control is in the charger.


Be interesting to know what voltage regulation is in the Brain. The motors run at a consistent speed with battery degradation but that might be mainly handled in the motors. That said, all the electronics will be on a regulator somewhere. IQ Brains are easy enough to open if someone wanted to take a look, just watch out for the pesky spring from the radio release button :joy:

I realize you’re new here, but we don’t like reviving old threads and adding repetitive information. As a rule of thumb, if the thread has been dead for over a month then think twice about posting.


It’s also in the community guidelines .


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