Special charger required?


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  1. haake

    haake New Member

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    I have several usb power supplies both AC and cigarette lighter styles that I have from other devices (treo and sky caddie) but I have been unable to get them to actually charge my droid. The one that came with the phone works fine and so does the usb on my laptop. I didn't really want to buy another car usb adaptor but it looks like I might have to.

    Anyone else have this problem with usb power supplies from other devices?

    Bill
     
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  2. shadowdude777

    shadowdude777 Well-Known Member

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    Make sure that the charger is rated at 5.1V (or as close to that as you can get) and at least 850mA.
     
  3. michaelk

    michaelk Well-Known Member

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    there's multiple threads- the droid follows the usb spec. So when first connected it draws ~100 mA (a trickle charge- barely enough to power the thing likely) then asks for 300 or 500 (or more with newer devices). The USB host is supposed to andswer if its OK to crank up to 300 or 500 (or more). If you have a cheap usb brick and it doesn't contain the logic circuit to reply to the droid then you will only get the trickle charge.
     
  4. michaelk

    michaelk Well-Known Member

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    not necessary- but the QUALITY does matter. there are multiple reports of poor quality devices giving "dirty" power and making the capacitive screen behave like it's possessed when plugged in.

    I have a chargpod which is no where near 5.1 and 850. It's a 6V 3000 mA charger and it works fine. The Droid pulls would it can handle - around 1500 mA and goes on it's merry way.
     
  5. kmfdmk

    kmfdmk Well-Known Member

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    You are on crack. It 100% matters. The voltage needs to be matched, and the amperage needs to be matched or exceeded. You're probably fine with the 6V, and MORE than fine with the 3000 mA (full 3A) output. You have to realize the phone will only pull as much Amperage as it needs (short of an electronic defect, like a short). Exceeding the rated voltage can cause instability, as well as damage to the circuitry in the phone. The circuitry traces on the boards, and the distances between SMT components are designed for a specific voltage. Too high a voltage and there's the potential over time for shorting, etc.

    Match Voltage 5.1v, meet or exceed the 850mA (milliAmps).
     
  6. shadowdude777

    shadowdude777 Well-Known Member

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    Yes, but what I (and the user above me) am trying to say is that he should AIM to match the voltage and match or exceed the amperage. 6V is acceptable because that's a very minor voltage fluctuation. Things are designed to handle such small changes in voltage. For example, USB is nominally rated at 5V and puts out something more like 4.5V when a load is applied to it.

    Personally, I'd be more hesitant to plug in a quality 12V power supply to it than a crappy 5V supply. The voltage is the single most important factor here, and THEN the "cleanness" of the power.
     
  7. johnlgalt

    johnlgalt Antidisestablishmentarian VIP Member

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    I used my Mom's BB Storm2 charger without ill effect.

    I then bought a car charger with USB output rated @ 1000 mA and a 10' USB to USB micro cable (the 10' goes in the home install, the 3' one that came with the MM Dock goes in the car).

    Win - win situation. Especially as the car adapter and cable including shipping were $4.50 US.....
     
  8. michaelk

    michaelk Well-Known Member

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    ok crack it is.

    point is the QAULITY matters just as much if not more than the specs.

    And there's plenty of phones getting charged by less than 850 mA- just takes them longer. Pretty much anyone pluggin the cable into their laptop is getting 500 mA (maybe only 300) and is getting a charge.
     
  9. michaelk

    michaelk Well-Known Member

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    of course- grossly outside of 5V is dumb- but I was saying I just dont think 5.1V is some magic number and a "generic" 5V USB charger is going to fail. If it's a high quality 5V (or 6V) then it will work just fine. Not sure we need to be to 2 or 3 significant digits.
     
  10. shadowdude777

    shadowdude777 Well-Known Member

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    Yeah, of course, we're just saying to match or exceed the amperage because then it'll be charging at a decent speed. And you made it sound like he should just totally discount voltage before when it's much more important than power quality. He should be aiming for something in the vicinity of 5V, maybe 6V tops, and then he can worry about the stability of the charger.
     
  11. michaelk

    michaelk Well-Known Member

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    sorry wasn't more clear- but i just figured any power adapter with a usb style port is going to be 5ish volts. But i guess some people might do odd stuff with power tips and the like.
     
  12. shadowdude777

    shadowdude777 Well-Known Member

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    That's a good point, I haven't really considered that. Fair enough, for USB- based chargers then, you don't really need to worry about voltage. That's the beauty of electronic standards, I guess! :)
     

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