Car Charger - Only works when voltage is above 13V

Discussion in 'General Discussions' started by Questor, Nov 14, 2016.

  1. Questor

    Questor Member

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    Hello All.

    I took my Mavic with me on a camping trip to the desert this past weekend. I had some great flights with the drone following my truck down some canyons using the activetrac mode. (Unfortunately, I was so excited by the flight that I forgot to press the record button.) :(

    But anyway, I went to recharge the Mavic's battery with the DJI car charger, and it wouldn't work even with the ignition on to supply power to the 12V outlet. It turns out the cars engine needs to be running at more than an idle to provide the 13V required. The battery will only charge when the car is driving.

    Just thought you should know.
    Q~
     
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  2. The Editor

    The Editor Well-Known Member

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    It works from 12.3-16v (Car) or 25-30v (Truck).
     
  3. LuvMyTJ

    LuvMyTJ Administrator
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    The DJI site has the specs The Editor mentioned... the full text is below along with the source link. :)
    If you camp a lot and want an alternative, those tiny gas gensets are pretty cheap these days for when your boon docking.

    image_25079.jpg $120

    Mavic - Car Charger
    USD $49.00
    Specifications
    Product Model: C3S78
    Operating Temperature: 41° to 104° F (5° to 40° C)
    Input Voltage: 12.3-16 V (Sedan); 25-30 V (Coach)
    DC Output: 13.05 V; 6 A; 78 W
    Charge Time*: 54 min

    * The charge time was tested in a lab environment at room temperature and should be taken as reference only.


    SOURCE: Mavic - Car Charger | DJI Store
     
  4. Easty

    Easty Well-Known Member

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    Your car will probably be 12.4v off and 14.8ish idle.

    You could get a $7 drok step-up and splice it into a cheap lighter socket extension. this would allow you to use that lead when the car is off. make sure its an 8amp capable one.
     
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  5. Questor

    Questor Member

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    It may be true what the DJI website says, but the car charger says otherwise.
    It clearly shows that the desired input is 13V.
     

    Attached Files:

  6. Questor

    Questor Member

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    Hello Easy.

    Where does one find a drok, and what do they look like? o_O
    Q~
     
  7. Easty

    Easty Well-Known Member

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    Here you go mate. https://www.amazon.com/DROK-Transfo...76278&sr=8-16&keywords=drok+voltage+regulator

    may look complicated if your not electrically minded. But its pretty easy. if you get a lighter extension like https://www.amazon.com/Breezesmile-...276514&sr=8-32&keywords=car+lighter+extention

    Splice the drok into the middle of it. You can plug the drok in without the charger and a volt meter on the output of the drok. Turn the potentiometer(screw on little blue box) until your volt meter reads 13. I've actually made a car 100w charger with a drok so i've played with it a bit and the mavic battery. I did a video on charging the battery at 100w of a bench supply, I'll do one for the car charger too. heres the vid if your interested Charging the battery at 100w, it doesn't get as hot as when it comes of the drone. Regarding the when the battery starts to charge its at 12.5v but you won't get full amp unless its 13v Create, Discover and Share GIFs on Gfycat <-- i tested it to calm the storm.. ;)
     
  8. SteveCA

    SteveCA Active Member

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    I tried the car charger for the first time today in my GMC diesel pick up. My truck has dual batteries and the car charger stopped charging shortly after turning off the ignition. It clearly requires more than 12.3 volts to do real work. It only charges properly with the engine running which is very disappointing. I have flown RC helis with up to 6s lipo packs that charged just fine on my truck battery (using Thunderpower and icharger lipo chargers)

    Is anyone successful using this charger when your engine isn't running?
     
  9. Easty

    Easty Well-Known Member

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    It's probably a step down converter mate with a current limit. So it won't be capable of stepping up the voltage if it's anything below 12.5v it won't start charging, see test I did above in the gif.
     
  10. Kilrah

    Kilrah Well-Known Member

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    It's most likely done on purpose as a low voltage protection to avoid discharging the car battery.
     
  11. Whitey

    Whitey Member

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    I'll be using my 600 Watt 12v DC to 240v AC inverter with the standard charger to charge mine when away from home.
    A fully charged 12V battery should have 12.6V (2.1V per cell x 6 cells).
     
  12. Easty

    Easty Well-Known Member

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    I used an inverter with the p4 all the time I had it, with no problems, its rather inefficient as your converting to ac and then back to dc, also the standard charger is only 3.5amp(50w). Issue with the car battery voltage at 12.6v is with zero load, soon as you add the charger, which in this case is almost 6amp(75w) the voltage will drop below the accepted 12.5v Easiest solution I think is to splice a voltage booster into lighter extension lead and use the pot to tweak it from 12.6v to 14.8v probably cost $15.
     
  13. FPVme

    FPVme Active Member

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    Hi Easty,

    Could I put these 3 items together and use the car charger to fast charge from a wall ac outlet?.....

    https://www.amazon.com/BINZET-100-2...=UTF8&qid=1479845706&sr=8-1&keywords=120w+10a

    Good DC 36V To DC 48V 4A 192W Step Up Power Supply Converter Regulator Module | eBay (drop down select 12v to 13.8v 10a 138w)

    https://www.amazon.com/Quality-Cigarette-Lighter-Connector-Adapter/dp/B015H6945S?tag=viglink20264-20

    I'm trying to have a portable solution rather then a bench power supply
    futher:

    Do I necessarily need to have that first item I posted (the adapter) be 10a out? Can I use a power supply that that has less amps since it's going to go into a step up which is going to output 10a anyway? The reason I ask is I can save a few bucks by finding a lower amp power supply.

    Thanks!
     
  14. Easty

    Easty Well-Known Member

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    Hey Mate. You need 8amp at least. You cannot step up ampage like voltage.

    maybe a booster with current control instead https://www.amazon.com/gp/aw/d/B01H...X236_SY340_FMwebp_QL65&keywords=Voltage+cv+cc

    Im assuming the car charger has current control but I don't own one.
     
  15. FPVme

    FPVme Active Member

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  16. Easty

    Easty Well-Known Member

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    Nah the booster is only 4 amp I think. do you have prime? this PSU is a similar price if so and has a built in plug https://www.amazon.com/Converter-HO...ncoding=UTF8&refRID=0K6NSM8C1TQ629PDVY3B&th=1

    Ah sorry didnt see the delivery date is way out on that booster I linked above. maybe just the regular drok booster and get an 8amp limited psu.
     
  17. FPVme

    FPVme Active Member

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    The psu amazon page I posted has multiple power supply... you have to click on the 12v 10a one.

    The one you posted is 12v. Unfortunately the car charger doesn't work on 12v (needs 13v)
     
  18. Easty

    Easty Well-Known Member

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    The Booster is only 4AMP not the psu

    also I was thinking to splice the booster into it. and save on buying the lighter plug. haha

    I'd get the 8amp PSU chop of the plug, connect the booster and then the chopped off plug onto the out of the boster. turn it on and maybe use a volt meter and tweak the potentiomenter so the volt meter reads 13v. then it should be good as the 8amps is limited by the PSU capability.
     
    #19 Easty, Nov 22, 2016
    Last edited: Nov 23, 2016
  19. TheLightSpeed!

    TheLightSpeed! Well-Known Member

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