Science Buddies: "Ask an Expert"

i am doing a project and am connecting solar panel battery chargers to a scooter's battery. i was wondering if i could get some help..
is there any device that can measure the power of voltage being used by a battery?

If I understand your question, a multimeter should do the trick:
http://en.wikipedia.org/wiki/Multimeter
You can buy one at Radioshack, Home Depot, or many other stores. Some people will have one in their tool-box at home.

A multimeter is the most basic and most required object for any type of electrical activity. They range from $20 for junk quality to $200 for top of the line. You can do very well for about $70 and keep it for the rest of your life.

Side note: Several years ago there was an article posing the question about why there are never any Tripplet 630 Multimeters on the used equipment market. The answer is that anyone who has one will never let it go. When he dies, his kids want it.

More recent versions are the digital multimeter. Different, but not much better.

Solar power sources tend to operate in a constant current mode, where the current is dependent on the illumination level. The voltage has a maximum based on the number of cells in the string. You will need to find a source with a voltage rating higher than the battery you want to connect to, but higher voltages are OK. A lower rated source will not be able to charge the battery. Do not worry about short-circuiting the solar sources, they can work just fine into a dead short.

The power levels are rather low. Sunlight is about 1000 watts per square meter and the solar sources are 10 to 20 percent efficient. Do not expect very much power from a small solar source. You may be charging all day for a few minutes of scooter riding.

Several years ago I worked on two projects related to the solar power sources on the space station. My parts are still on the ground, but may be in space someday.

Robert Reavis

thank you for all of your help