# Solar charged Gameboy color

#### D.Pillman

Joined Nov 7, 2010
5
I have two calculator solar panels connected to two rechargeable batteries, which are in a Gameboy color. I also have a diode that controls the flow towards the batteries, from the solar panel. As I am writing does the diode have to be connected to the negative wire to direct the flow correctly?

Gameboy color
Minimum voltage 2.4
Minimum amps .3

The rechargeable batteries
Info from the charger
Input Voltage 5VDC
Output Votage 1.4VDC
Charging Current 200mA

Solar panel info
What I got form the multimeter
Output Voltage 3.83
Amps .011mA

with the info I believe that I am not producing enough amps, is there a cheap way to increase the amperage?

#### Audioguru

Joined Dec 20, 2007
11,248
Nothing matches anything.

Your Gameboy needs at least 2.4V at 300mA.
But your charger and rechargeable battery are only 1.4V which is far too low.
Your solar panel supplies only 11 mA which might charge the battery in a week if it has no load.

Yopu need to match everything and supply enough current (a much bigger solar panel).

#### D.Pillman

Joined Nov 7, 2010
5
Im really new, thanks for the advice, I have 2 2450mAh rechargables with the same specs, I also looked up other solar panels, and have two new questions. the solar panels that will work with my budget produce 200mA, and 1 volt. If i connect them in series they should produce 2 volts right. and my other question which im sure is a no, using that can i charge both batteries using a total of 2 volts and 200mA if each batter needs 1.4 V to charge and a current of 200mA?

#### D.Pillman

Joined Nov 7, 2010
5
According to Enegizer, the Batteries will trickle charge with a current of 50mA. if i have 200mA will it be too powerful, and will it be able to charge two AAs that are connected in series???

#### wayneh

Joined Sep 9, 2010
17,493
No charging at all will occur when the panel voltage is less than the battery's voltage plus about 0.6 volts which are lost across the diode. So for a battery at 1.4v, you need about 2v from the panel for anything to begin.

A rechargeable battery can be charged at any rate up to a maximum that is too high for you to worry about (eg. 2 amps). There are various strategies to reduce rate as the battery nears and reaches full charge, but a small solar panel will be lucky to trickle, and you needn't worry (much) about slowing it down.

If you want to charge a 2450 mAH battery, you need both mA and hours, and the multiple of those two numbers to be ~2450. (Actually more, because of inefficiencies.) For instance, charging at 245mA for 10 hours will give you nearly a full charge from a nearly fully discharged battery. In reality though, you shouldn't drop below about 50% discharge, so 5 hours would do it for a "normally" discharged battery.

If you get a bigger panel, say one that could charge it fully in 3-4 hours, you'll have to learn about current limiting, charge management and such, to avoid frying your batteries.

#### chimera

Joined Oct 21, 2010
122
hey pillman, we met at radio shack last friday. Well, im glad you made your way to this forum. As you can see from the replies, your project is experiencing some difficulties finding its way into the functioning world.

I think that you need to find a solar panel which is capable of providing the right current and the voltage as one unit. Charging the batteries is not that big of problem.

Since your limited by the budget, this project might need some changes in the requirements and the output. For instance, you either need to buy a bigger solar panel or you need to reduce the load (game boy) so that the system can comply with the rechargeable batteries and the solar panel ratings that you currently have.

#### Audioguru

Joined Dec 20, 2007
11,248
Did you notice that when it is cloudy, the sun is blocked?
Did you notice that when it is sunny, the sun is mich brighter at noon than in the morning or in the afternoon?
Did you notice that the position of the sun in the sky changes during a day?
Then your solar panel will not procuce 200mA all day long, only at noon. It might produce an average of only 50mA per hour over an 8 hours sunny day.

#### D.Pillman

Joined Nov 7, 2010
5
I did take notice to it, also the two panels are producing 2.06V in direct sunlight, and 106 mA. here is a rough sketch of the system, the batteries are in the gameboy.

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#### wayneh

Joined Sep 9, 2010
17,493
... the two panels are producing 2.06V in direct sunlight, and 106 mA
Where are those mA going? Do yo mean you are getting 106 mA of charging current (which I doubt) or 106mA when you connect your panels directly to the ammeter of your multimeter? Even in that case I'm a little surprised you're getting that much current. Are you sure those aren't micro-amps, not milliamps?

Your schematic is the very most basic, but correct. Putting your multimeter is SERIES with the current will allow you to measure the charging current, which will be slightly lower when measured than when the multimeter is out of the circuit.

#### D.Pillman

Joined Nov 7, 2010
5
I used a multimeter, and its listed as mA. Im currently looking into getting a solar panel set that charges rechargeable batteries, and connect that to the circuit instead of the current solar panels. when i connect my multimeter to the solar panels that is what i get, 105mA they are rated for 200mA.

#### Audioguru

Joined Dec 20, 2007
11,248
I have a solar panel rated at 12V/150mA. Its output voltage is about 18V with no load. I did not measure its shorted output current because it is not used when it is shorted.
At noon in April (I am in North America) with it pointing directly at the sun its output voltage is 12V when its load is about 120 ohms (then its current is only 100mA). Its output current will probably be 150mA at noon in July with it pointing directly at the sun.

#### wayneh

Joined Sep 9, 2010
17,493
I used a multimeter, and its listed as mA. Im currently looking into getting a solar panel set that charges rechargeable batteries, and connect that to the circuit instead of the current solar panels. when i connect my multimeter to the solar panels that is what i get, 105mA they are rated for 200mA.
I didn't think a calculator solar panel would give that much current, but anyway, as you've described your measurement, that was measured as a short across your meter. That means the voltage would have been very low.

Getting a bigger panel is the way to go. If you want to stay cheap, look for those solar landscaping lights. You can get those really cheap, \$2 or so each brand new, and they will contain a nice panel and even all the circuitry you need to charge a battery. You might want to hook some of the panels together into a single unit, to get a faster charger.