How many amps does a 1.5 volt, AAA battery produce?

Question

I need to find out why three AAA batteries powered a small motor that a 10 watt solar panel could not power. The 10 watt panel produces 21 volts, but I can't figure out how many amps it produces.

Answer 1

Your solar panel produces 10 watts of power at a no-load voltage of 21 volts.  That means that your panel should be able to generate (10 watts / 21 volts), or around 470 MA of current into a high-impedance load.

What is happening is that the load impedance of the motor is such that it's loading your panel down and the solar panel cannot generate significant enough voltage and current to drive the motor.  Also, these solar panels don't respond well, to equally, to all wavelengths of light.  For example, if you are using a desk lamb to power your solar panel, it will not function as well as if you were using sunlight.

I have ran into the same problem that you are currently experiencing.  I found that if I add a series resistor of a few hundred ohms between the motor and the panel, it will actually cause the motor to run when power by the solar panel, but not very well.

I haven't figured out a way to solve this problem without adding some kind of battery backup to the solar panel. But it is a loading, impedance problem.

Answer 2

10w 21V solar panel max output is then 0.5A

Single AAA battery can produce easily 1A for limited time.

Motor probably needs more current to start than what the array can produce.

Try connecting electrolitic capacitor of larger capacity in parallel to array. It could help with motor start

Answer 3

An AAA battery is rated at 1000mah. So that would be 1 ampere for 1 hour. I would say you didn't have enough current capacity to run the motor or, not enough sun. Measure the voltage across the motor when it is connected to the solar panel. See if you have any voltage there.

Answer 4

Ohm's equation comes to mind. Basically, you need to know the resistance of whatever you're hooking it up to to determine the current. Ohm's law states:

V = I*R

Where V is the voltage in Volts, I is the current (amps), and R is the resistance in ohms.

Answer 5

It's not what the panel produces with no load that counts, but what it produces under load.

I suspect that when you put the motor on the panel the voltage output dropped to zero. Probably because the current that the motor drew was more than the panel could supply.

What is the rated voltage and current of the panel?

If you want to experiment, get a bunch of 10 watt resistors and measure the voltage out of the array with different loads attached. This will give you the current capability of the array. I'd start with 100 ohms, then 50, then 20 ohms.

You can also get an ammeter and measure the current drawn by the motor. It could be several amps.

Answer 6

One thing you've got to consider with most any power source is the source impedance.

If you really load the circuit the voltage will drop considerably.

The 10W panel might produce 21V at no load but I bet it dropped way down to nearly zero when you connected it to the motor.