Ironic
Newbie level 4
So i want to have a emergency cell phone charger.
I want to use batteries that i can use in other devices so i´m planning on using 4 AA NIMH. (already have a holder for them)
So i need 5V at 500mA (actually measured cell phone while charging and it's 350mA)
I've designed a simple boost converter based on an PIC, that maintains 5V at the output (using a 10ohms resistor to simulate cell phone)
The thing is when the batteries are charged their voltage is about 5.5V, so with the voltage drop in the diode the output is around 5V without the need to turn on the boost converter.
When the voltage battery starts to drop the boost converter kicks in and keeps the output at 5V until the batteries are about 4.5V, after witch they cant put out enough current to feed the boost converter.
My question is then, should i even bother with the boost converter? Isn't the range 5.5V to 4.5V safe enough to connect directly to the cell phone? I could just use the pic to cut off voltage when batteries are below 4.5V.
Thank You
I want to use batteries that i can use in other devices so i´m planning on using 4 AA NIMH. (already have a holder for them)
So i need 5V at 500mA (actually measured cell phone while charging and it's 350mA)
I've designed a simple boost converter based on an PIC, that maintains 5V at the output (using a 10ohms resistor to simulate cell phone)
The thing is when the batteries are charged their voltage is about 5.5V, so with the voltage drop in the diode the output is around 5V without the need to turn on the boost converter.
When the voltage battery starts to drop the boost converter kicks in and keeps the output at 5V until the batteries are about 4.5V, after witch they cant put out enough current to feed the boost converter.
My question is then, should i even bother with the boost converter? Isn't the range 5.5V to 4.5V safe enough to connect directly to the cell phone? I could just use the pic to cut off voltage when batteries are below 4.5V.
Thank You
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