Solar panels and electronic tinkering

[wayacoyote]

We're not talking home systems here. My wife has a back-up weather radio that has a solar cell on one side and an hand-crank at the end. With my multimeter, which I know nothing about, I found that the solar cell is putting out 5volts and the hand-crank puts out 1.5volts DC.
The radio doesn't work, so I'm looking for other things that my boy and I can do with these. I just bought a 6V rechargable battery for my deer feeder. Can I use the solar cell on it? how?

Any little gizmos that we could build to grow our electronics knowledge?

[Sundance]

The short answer is that you should be able to use
the solar panel on the 6V system. The big question
will be the panel amp output if you know that.

Others can help more with any control that might
be needed to prevent overcharging.

[drobbins]

I think to charge a 6 volt battery you gotta make more than 6 volts
you can do this with a transformer which you can probably salvage out of some broken stuff of maybe even out of the weather radio
better yet, if this is a learning project, build your own
I bet someone more knowledgeable will come on and tell you how

Dave

[wayacoyote]

Transformers:
Do they alter voltage and amperage inversely?

How do I determine the amp output? Does it have to be under load?

[drobbins]

>>Do they alter voltage and amperage inversely?

yea
I think if you have 20 coils in the primary and 10 in the secondary you'll get twice the volts and half the amps
or the other way round
I'm not an electric guy
might be a fun project

Dave

[carbide]

Transformers only work in AC circuits, ie. there has to be a collapsing magnetic field for a transformer to function. DC voltage is a non varying voltage. The voltage coming out of the solar cell will be DC voltage. You will need more than 6 volts to charge a 6 volt battery, probably around 6.6 volts.

The voltage coming out of a transformer is directly proportional to the number of wire wraps in the primary and secondary windings. If you have 20 windings in the primary and 10 windings in the secondary the ouptut voltage will be one half the input voltage. If the primary has 10 wraps and the secondary has 20 wraps the output will be twice the input voltage. Amperage is inversely proportional to the voltage. In other words if the output voltage is double the input voltage, the output amperage will be half the input voltage and vice versa.

These numbers don't take into account the normal losses in a transformer such as wire resistance, hysterisis, eddy currents, etc. Your actual values will vary depending on the transformer's physical characteristics.

[magnet-man]

Carbid is correct. You will need higher voltage than the 6 volt battery. Since your cell only produces 5 volts you need to convert it to ac voltage and step it up with a transformer or a diode multiplier and then convert it back to DC.

When I get back home from my trip I will send you a schematic of the circuit.