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Makers and Making: DC Power Station for Many Cell Phones
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Feb 9th 2006
Ok, I really need help with this. I have several prototypes without power, (or rather, I have been forced to use an AC power strip with 30 individual, ugly chargers and a mess of wire everywhere) here is the situation:
I need to be able to charge 30 new cell phones on a single power supply. Through some risky experimenting on my part, I have been able to charge 3 cell phones off of a single wall transformer, and I know I need more power to get 30 up and charging. I have thought of using a modified laptop/PC power supply, and I think it will work, but I do not want to risk blowing up 30+ $300 cell phones which are not mine to blow up. Here are the specs I am working with now:
Original cell phone charger is : INPUT AC 100V-240V 200mA 47-63Hz
OUTPUT DC 4.5V-9.5V max 800mA
Cell phone batterys are: Li-ion 3.7V
What Kind of DC power supply / set up do I need to charge 30 phones? Is there a safe way to do it, and what precautions should I take? Any Help would be greatly appreciated
I need to be able to charge 30 new cell phones on a single power supply. Through some risky experimenting on my part, I have been able to charge 3 cell phones off of a single wall transformer, and I know I need more power to get 30 up and charging. I have thought of using a modified laptop/PC power supply, and I think it will work, but I do not want to risk blowing up 30+ $300 cell phones which are not mine to blow up. Here are the specs I am working with now:
Original cell phone charger is : INPUT AC 100V-240V 200mA 47-63Hz
OUTPUT DC 4.5V-9.5V max 800mA
Cell phone batterys are: Li-ion 3.7V
What Kind of DC power supply / set up do I need to charge 30 phones? Is there a safe way to do it, and what precautions should I take? Any Help would be greatly appreciated
Feb 9th 2006
Wow, they take up to almost an amp each, that's a lot. Probably overspec'ed
Since it appears from the specs that there is a charging circuit inside the phone, you can just use a 5v power supply. Any linear 5v supply should work. A switcher might not be too happy without a load. You could also get one of the bench power supplies, which is nice because most of them have current and voltage meters.
Then you have the issue of getting the cables.
Since it appears from the specs that there is a charging circuit inside the phone, you can just use a 5v power supply. Any linear 5v supply should work. A switcher might not be too happy without a load. You could also get one of the bench power supplies, which is nice because most of them have current and voltage meters.
Then you have the issue of getting the cables.
Feb 9th 2006
You might want to look at power supplies designed to work with guitar effects pedals, which usually use DC 9v. These are designed to be incorporated into pedal road cases and so are compact and usually well designed. Almost all use either barrel or 3.5mm jack connectors as the outputs for each tap, which makes modding the phone power cables pretty easy.
You will want to measure the current draw of a phone needing a full recharge and see if this type of PS will supply enough juice. There are many brands, configs available. Search on "effects pedal power"
Be aware that some are designed to work with pedals requiring AC power, or 12.5v DC. They can be a bit pricy (+$100) new, but I've seen some good deals on used ones on Ebay.
If you don't care about size or noise and/or you want to hack it together yourself, go with a PC switcher, there are plenty of articles on modding these on the web.
You will want to measure the current draw of a phone needing a full recharge and see if this type of PS will supply enough juice. There are many brands, configs available. Search on "effects pedal power"
Be aware that some are designed to work with pedals requiring AC power, or 12.5v DC. They can be a bit pricy (+$100) new, but I've seen some good deals on used ones on Ebay.
If you don't care about size or noise and/or you want to hack it together yourself, go with a PC switcher, there are plenty of articles on modding these on the web.
Feb 11th 2006
I like the idea of using the guitar effects pedal power supply. I looked them up and they seem to be a great solution that I wouldn't have thought of otherwise. Thank you for the great ideas!
Feb 20th 2006
Well,
I have done a bit more research on charging these things up, and I came across this video that shows what happens if a Lithium battery (which is the type used in most cell phones) is overcharged... I might abandon this project unless I can find a way to safely avoid the battery blowing up.
http://www.troybuiltmodels.com/LithiumBattery.wmv
I have done a bit more research on charging these things up, and I came across this video that shows what happens if a Lithium battery (which is the type used in most cell phones) is overcharged... I might abandon this project unless I can find a way to safely avoid the battery blowing up.
http://www.troybuiltmodels.com/LithiumBattery.wmv
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