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Safe supply voltage for cell phone

I have a Motorola V550 cell phone. When I use it as a modem, it drains its battery quickly. So, I decided to make an auxiliary power supply for it, to be used when I am away from AC power.

The phone's AC adaptor supplies 5.81 volts when the phone is not plugged in, and 5.61v when the phone is charging. The phone starts charging when supply voltage reaches about 4.8-4.9 volts.

I bought a battery pack that has about 6.7 volts when fully charged.

I would like to know if, in your opinion, it can be simply connected to the cell phone directly. Or is 6.7 too much.

If, in your opinion, 6.7 volts is too much, an easy option to consider is to just add a diode like N4007 for a 0.7 volt voltage drop.

Any thoughts will be appreciated etc.

i
Reply to
Ignoramus15609
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I'd put a diode in series just to be safe. It'll probably be fine either way but you can't really tell without looking at the circuit design.

Reply to
James Sweet

I'm not sure if the .9 or so volts would be to much but you might not want to risk it since theres no reason to. You can use a diode but make sure you get one that can handle the current(look at the AC adapator and see how much its rated for). Ofcourse if you use a diode you'll be wasting that power but if you don't mind then its no big deal(not like its that much anyways).

Since your using it as a modem you might want to tap into your computers supply. It should have a 5.x(not sure bout a laptop but I would imagine it must have one) voltage that you can use. Should be ok as long as the cell phone doesn't use to much current and would probably be worth the effort instead of having to have to seperate supplies and waste the batteries.

Reply to
Jon Slaughter

then you want 4.something volts

too much by about 2v

Get the right battery, trying to drop it may damage the phone. Diode drop depends on current, its not 0.7v IRL except at i~=0.

NT

Reply to
meow2222

I thought that the ideal voltage would be 5.61 volts.

Thanks. Some people recommended some low dropout regulators that could be helpful for me.

i
Reply to
Ignoramus26085

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