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1000 mA not enough for GPS?

Discussion in 'Android Devices' started by jackburnt, May 17, 2010.

  1. jackburnt

    jackburnt Well-Known Member
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    Auburn, AL

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  2. Groid

    Groid Well-Known Member
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    Uh-oh, I just ordered one of these last Friday. I had a Kensington mini car charger rated at 700 mA and it worked beautifully, but I gave it to my wife after she got a Droid. I could run gps and still slowly gain charge. Is there something about these things that would make 1000 mA not work properly?
     
  3. goldrush28

    goldrush28 Well-Known Member
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    Not sure where I read it, but I remember seeing that you need a 1300 to charge properly. That's what I got and it works great for everything.
     
  4. shadowdude777

    shadowdude777 Well-Known Member
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    If you have a multimeter it might be worth your while to use it to check the amperage coming out of the USB port. Look inside the USB port and you should see 4 metal pins lying on the black plastic piece. The two outermost ones carry power, so plug the charger into your car's cigarette lighter, set your multimeter to the appropriate range to check amperage and touch one lead from the multimeter to one of the outermost pins and one to the other one.
     
  5. jackburnt

    jackburnt Well-Known Member
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    I'll give that a shot.
     
  6. thenew3

    thenew3 Well-Known Member
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    I have a no name car charger that says it outputs 550ma. I have no problem using GPS on the droid and have it charge as well. It does take a lot longer to charge though. On a recent 2 hour trip, while using the droid as a GPS, it was able to charge it from 50% to 100%.
    On a regular home charger, It would take about 45 minutes to charge from 50% to 100%.
     
  7. Penguissimo

    Penguissimo Well-Known Member
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    1000 mA is more than enough to charge while using GPS. Even the Motorola-branded car charger is only 850 if I recall correctly.

    The battery-draining issue is likely one of heat rather than charging capability; if your phone is in direct sunlight while you're using it as a GPS, it can overheat, which causes the charging circuit to scale back or shut down automatically. Try either moving the phone out of the sunlight or aiming the air conditioning at it and see if that helps.
     
  8. 91STT

    91STT Member
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    This may not be a good idea. An ammeter presents a negligible load to a circuit and will act like a short. At best the readings will be meaningless since it is the no load current. At the other end of the spectrum, damage can occur to the charge, meter or both.
    The OEM wall charger is rated at 5VDC-850mA, so I would surmise that 1000mA should satisfy your needs.
     
  9. Polymira

    Polymira Well-Known Member
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    Your charger isn't outputting more then 500-550mah.

    I used to use an old belkin iPhone charger in my car with my iPhone, then Hero, then Droid .. and on the Droid when using google navigation and pandora my battery would go down .. slowly, but it would go down.

    Once i purchased the official motorola charger (850mah i believe), no matter what i'm doing on the phone it's still rapid charging... which is super awesome.
     
  10. PhilosoRaptor

    PhilosoRaptor Well-Known Member
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    Which official Motorola charger? I have this one and it still drains my battery when navigating with Pandora playing.
     
  11. shadowdude777

    shadowdude777 Well-Known Member
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    Yeah, that last part is the important part. I'm thinking that since 1A should definitely satisfy his needs, perhaps the cigarette lighter port is current-limited, in which case just an ammeter wouldn't be considered a short.
     
  12. takeshi

    takeshi Well-Known Member
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    Could be your vehicle. Could be the Droid's battery heating up.

    950mA (what mine outputs) is plenty to charge my Droid while using GPS.
     
  13. 91STT

    91STT Member
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    A car's cigarette light or 12V accessory port is current limited by the fuse, a late model Ford Ranger is 20A.
    An ammeter is always considered a short since by design it presents negligible or virtually zero load to a circuit. An ammeter in practice is never connected across a power source. In this case the charger is considered a power source.
    From the description, this charger is most likely employing a 7805 voltage regulator. I do not know of any that are not designed with short circuit protection and because of this the ammeter readings across the output would be meaningless. Using an arbitrary load, such as, a resistor as a substitute without knowing the actual load would also give meaningless results.
    Since the OEM wall charger is rated at 850 mA, I'm guessing the Droid would draw no more than 650, maybe 700 mA nominal.
     
  14. shadowdude777

    shadowdude777 Well-Known Member
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    Oh, alright. I was set on the idea that a car's cigarette lighter port was current limited by a resistor and not a fuse. Guess it doesn't help that I don't have a car... my bad :rolleyes:

    Perhaps the charger he bought is only rated for 500mA? That is the standard for USB, and the manufacturer might have thought that there's no sense in designing the charger for more.
     
  15. jackburnt

    jackburnt Well-Known Member
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    Truck's a 2003 Ford Ranger, if that helps.

    And the charger is rated for 1000 mA (I linked to it in first post).

    Heating sounds like the most probable, and unfixable, solution.
     
  16. CRPercodani

    CRPercodani OFWGKTA
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    M A dub'l dolla sign
    I stopped reading right there, problem solved!
     
  17. PhilosoRaptor

    PhilosoRaptor Well-Known Member
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    Ay now, mine has 220k miles on it, has been through hell and still runs perfect. That certainly aint the prob :p.
     
  18. PreciousMetal

    PreciousMetal Member
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    I have over 340,000 miles on my 96 FORD F-150 4x4. Everything on it works and I have been known to beat it up pretty good offroad. I know many people who are at 200,000 miles on their FORD trucks.

    So go kick rocks chevyboi :D
     
  19. riffdex

    riffdex Well-Known Member
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    Slightly related question:
    I ordered a car charger off ebay for my Droid. It does not say the mA on it and I was wondering if I could find this out? I mostly just want to make sure it will be powerful enough to charge the phone while using GPS. I do not use GPS that much (don't have a reason to most of the time) and I would rather find out if it can be charged (with GPS) right now, instead of finding out when I'm on a 2 hour trip where I need the GPS.
     
  20. UncleMike

    UncleMike Well-Known Member
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    Not to dig up an aging thread, but I have exactly the same charger, which appeared to work fine until I had to start using my Droid for GPS while my Tomtom was out for RMA replacement. Without really paying attention during the day, I noticed that at the end of the day my battery meter was often lower than usual. A quick test today showed that while using my Droid for GPS navigation and "charging" using the above charger, my battery was actually discharging.

    On the return leg of the trip I used a Sprint-branded charger rated at 850 mA and my battery ended up charging during the trip.

    The back of the phone was warm after each leg of the trip; about equally so regardless of which charger I was using.

    My reason for buying the charger in the first place was not that it was cheap, but that I could connect it to a longer (15 foot) cable, to allow me to route the cable neatly from my CLA socket to the top of the windshield where I have the phone mounted.

    Could the length of the cable I'm using be a contributing factor?

    I also thought that possibly the Droid is seeing this charger as a USB power source, as opposed to an AC power source, and that it was intentionally drawing less power, but both chargers I mentioned appear to Tasker as only an AC power source, whereas my multimedia dock with its charger appears as both AC AND USB to Tasker.

    I suppose I should mention that my test vehicle is also a Ford.

    Aside from cutting open a cable connected to this charger, and connecting a meter with the charger under load, is there any way to know what power is actually being drawn and/or supplied?
     
  21. Redflea

    Redflea Well-Known Member
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    I've had similar issues w/charging when using GPS (and sometimes also streaming podcasts on Google Listen).

    As the phone/battery heat up, charging slows down, and even stops...I've had the battery level fall even while plugged in...this is w/the phone sitting in full sunlight while doing GPS/Podcasts...seems like the heat is just too much for the charging process. I'm going to put a small cloth over it next time to provide some shade, and may also look for a vent mount to use to try to keep it out of direct sunlight.
     
  22. shadowdude777

    shadowdude777 Well-Known Member
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    You should try the charger you got from Monoprice with the regular super-short USB cable that comes with the Droid and see how that works. I know it's inconvenient, but it would help isolate whether or not the cable length is an issue, and that's what troubleshooting is all about! ;)

    But yeah, USB power has the potential to be VERY lossy with longer cables, especially if the cable manufacturer decided to be cheap and use particularly thin-gauge wire. I would try a shorter cable and report back! :D
     
  23. UncleMike

    UncleMike Well-Known Member
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    Will do. I know there is a loss in any cable, but I was hoping to be able to use something other than the short coiled cord that is part of most chargers.

    Further investigation uncovered this on the product page:

    Maybe it is really rated at 500mA.
     
  24. shadowdude777

    shadowdude777 Well-Known Member
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    That's odd... when is it rated for .5A and when is it 1A? Maybe 1A is with 24V input or something? But that would be a REALLY WEIRD way to do it... so I don't know.
     
  25. overcaffein8d

    overcaffein8d Well-Known Member
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    Took a long trip up i-95 a few days ago and ran into this problem. I had also come across this thread earlier because i've had the same problem.

    My conclusion: I'm pretty much certain it's the heat.

    Since i don't have a vent mount, i came up with a workaround. Just turn on the air conditioner as cold as it gets--but instead of setting it to come out of the normal vents, set it to blow out of the windshield vents (as if defog...but cold).

    this worked for me, but YMMV. After awhile, you can turn down the air conditioner to half power instead of full blast and it should keep it cold.

    or just take it out of the sun for a few minutes.

    hope this helps
     

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