A question about the game boy advance battery charge led lig

[themist912]

Hello I am a newbie to modding and well circuts to be flat with all of you.

So I have a question about the gameboy advance light indicator for the battery charge level.

Uhh how does it work eternally

like on the circuit board I get that it turns green when it is juiced and red when it is running low

but like what does it actually do in the background to well show all that.

If anybody could help me out and show me some simple diagram or explain it to me that would be great.

Like I said i'm interested how it internally works.

 

[Aux]

Re: A question about the game boy advance battery charge led

A low battery indicator circuit is based on two major principals of electronics: battery voltage discharge curves and transistor switching.

Firstly, we normally think of batteries as having a steady voltage, i.e. a Li-ion has 3.7V. However, when a battery is discharging from fully-charged to "dead", it actually gives off a range of slowly-dropping voltages. Fully-charged it might give 4.2V, and discharged, down to 3V or even less. Here is an example of a specific lithium polymer battery's discharge curve:

So by knowing a battery's typical discharge curve, and by measuring the voltage coming out of the battery, we can figure out how far along this curve we are and know what percent of battery we're at. If you're using a fairly constant amount of battery power, you can also take a guess at how long you can run for until the battery will die. This is how your laptop knows you have "2 hours remaining" or what have you, but then when you start up a game or something that uses a lot more power, it'll drop.

Important point: lithium ion batteries can be irreparably damaged if run down until they're giving off around 2.7V or less. For this reason people invented protection circuits that shut off the battery, usually around 3V. Never connect a lithium ion directly to your circuit without a protection circuit in between- you will have a bad time!

So the second part that runs those low battery indicator circuits is transistor switching. Transistors are neat electronics components that allow electrical signals to switch other electrical signals. This allows us to set up a circuit (like DaftMike's Low Battery Indicator) that allows the level of voltage coming from the battery to switch on or off power to different LEDs. That post has a lot more information of the actual mathematics of the transistor circuit, if you're interested.

...Did I help?

 

[SNEAKxxATTACK]

Re: A question about the game boy advance battery charge led

Love seeing Aux's posts, well any of the veteran modder posts, I learn so much from them.