Solar panel & Droid phone charging; electrical question


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  1. yzingerr

    yzingerr Well-Known Member

    Solar panel & Droid phone charging; electrical question?
    I am buying a 12V 5 watt solar panel to keep my vehicle battery charged. I am wondering if this same panel could charge my droid phone and what i would need to do to accomplish this. Im sure a voltage regulator is needed in the very least. I dont know the amp output of the panel, but i believe the droid needs 1000mAh

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  2. olskool

    olskool Well-Known Member

    The answer is in the panel. If it has an alternate plug in, just use car charger. It will regulate by design.
    If no alternate, charge inside car. Solar charge takes longer, but will work.
  3. takeshi

    takeshi Well-Known Member

    1000mAh is a battery rating. Current would be mA/A.
  4. yzingerr

    yzingerr Well-Known Member

    i was hoping to be able to carry the panel into the field away from the vehicle to charge my phone
  5. olskool

    olskool Well-Known Member

    This would depend on the outlet setup. You can build a converter plug with a little savy and a dc voltage tester. The key to this is polarity. Since the output polarity + - is set coming out of panel, when building the converter plug it has to match what goes into charger. + to + and - to-. This is because the output is already dc. Got it? If you need more just give me more detail about panel output and check back. Visit my profile and maybe pm to save time and noise.
  6. yzingerr

    yzingerr Well-Known Member

    it is currently enroute to me, i will check it out and relay back to you. thanks!!
  7. johnlgalt

    johnlgalt Antidisestablishmentarian VIP Member

    I'm guessing that it either 1) connects directly to the battery, in which case you'd have to rig up a way to attach a cigarette ligter plug to it in order to use a charger, or 2) it plugs into the car's cigarette lighter plug. If that is that case, then you might need a single to dual adapter, so that you could plug both the charger for the phone and hte solar charger into your cigarette lighter plug single to dual adapter, plug the adapter to the car's cigarette ligher, and charge both.

    in hte latter case, the single to dual adapter should *also* suffice for use in hte field as the phone's car charger will automatically regulate both voltage and amperage (by design).

    Also, technicaly specifications show that microUSB is supposed to provide up to 500 mA, but most car chargers vary up to 1000 mA, and the electrical chargers rom Motorola supply 800 mA. The lower than 1000 mA that is supplied to the phoine, obviously the slower the charge. The quality of the product (wires, charger, etc.) also makes a huge difference. I bought some USB-A to microUSB cables from monoprice - they are much more sturdy, thicker, better insulated, and larger guage wire inside - and they, from the same electical outlet device made by Motorola charge my phone at different rates. tested with two different batteries....

    See my post here for the monoprice links to cigarette lighter adapters http://androidforums.com/motorola-droid/17365-droid-battery-issues-charging-slowly.html#post110803

    in fact, that whole thread is a very good read....
  8. yzingerr

    yzingerr Well-Known Member

    thanks john, I will look at the thread!
  9. yzingerr

    yzingerr Well-Known Member

    Btw it has MC Connectors to the panel and alligator clips to the battery
    johnlgalt likes this.
  10. desmofan

    desmofan Well-Known Member

    Another thing to consider is the output voltage of the solar panel. I don't think the charging circuit in the Droid would like 12V very much, so you would have to step down the voltage. I think the post above about a dual cigarette lighter adapter may be the easiest way to go. as the panel you are buying does not have this as an output, you would have to wire the panel output to an adapter. I use one of these solar chargers in my truck, to keep the battery charged as I don't use it often. It has a cigarette lighter plug as the output, and I simply plug it in and place it on the dashboard. Anything you have to clip directly to the battery would not seem as user friendly, so you may want to consider a different panel.
  11. johnlgalt

    johnlgalt Antidisestablishmentarian VIP Member

    I suspected something of the sort. I assume that alligators can then be rigged to a makeshift cigarette lighter that you can purchase from an auto shop (autozone, O'reillys, etc.) then then you *should* be good to go.

    If he is using a car charger, it is also taking 12 V from the cigarette lighter and stepping it down.

    That's the whole reason I made use of a car charger in the first place for both of my suggestions - to eliminate that variable. :D

    Also, while it has alligator clips to connect directly to the post s(terminals) I'm guessing you could quite possibly connect them to a live grounded circuit in the car as well, just as long as you didn't try to run the starter off of it :p

    @yzingerr - to say the least, it would make for a good experiment - but you might want to have a multimeter around to test output voltage from your rigged cigarette lighter adapter and from the car charger when it is insert in there, just to be sure. Common sense says it should work just fine, but...I don't know if the stock (Motorola) car charger has some sort of circuitry to monitor if it is plugged into a car or not, and / or if it is fused (I think it is supposed to be fused, but I don't use the stock car charger in the first place, so I don't really know.
  12. yzingerr

    yzingerr Well-Known Member

    I definitely think that connecting the car charger to the panel and then to the phone is the best option. I really dont care if I fry the charger, but the phone being fried would really suck. I guess ill have to do some research to see what the appropriate output voltage should be...
  13. johnlgalt

    johnlgalt Antidisestablishmentarian VIP Member

    The output voltage should be 12 V as in your OP. Otherwise it would not work as a Car battery charger.

    The car charger I'm referring to is a Phone car charger that plugs into the cigarette lighter - as long as you're using one of those it is going ot adjust the voltage to your phone's specification every time.

    There really should not be be a problem, b/c even if the cigarette lighter receptacle (adapter as I was calling i before) that you wire to the panel shorts, it won't overload the car charger with voltage

    Also, since Wattage is Voltage times Amperage, 5 W = 12 V * .416666... repeating Amps, or 416.6666...repeating mA, which is just under the Amperage supplied by normal USB connections on computers.

    As long as you get a Car Charger unit that supplies your phone with the correct voltage, you should be golden - provided that the panel is supplying you with continuous voltage, as opposed to that 5W value being a peak value.

    The car charger that I use is the following: PowerJolt Dual - which I picked up at a local Wal-Mart.

    Here is a cigarette lighter receptacle that you could use: Duralast/Cigarette Lighter Connector (816) | AutoZone.com
  14. yzingerr

    yzingerr Well-Known Member

    I have an extra accessory cigarette lighter plug, now to figure out how to get an MC connector fitted to it ?!?!?
  15. olskool

    olskool Well-Known Member

    O.K. you have panel now you have option to do butt connections. Cut cable for car gator clips and put quick connecting plugs @ both ends. Switch male female connect ends so you can't cross polarity. 1 mal 1 female on 1 side etc. Do same with lighter adapter careful with polarity. Don't worry about volt/ amp just make sure polarity matches. You don't step down anything because you have amps regulated by charger. The output rating of panel is most likely 13.7v @ x amps and 1.7 drop in v through zener diode for v regulation. Any device connected will only DRAW from a max BANK the amount needed to operate. Just as if you plug in a bulb to a D.C. power supply.
    Amps will take care of itself. Polarity will kill you. I would also place an in line mini breaker or fuse for protection... now you can leave gator clips for car in car and plug/unplug adapter as needed.
  16. yzingerr

    yzingerr Well-Known Member

    Thank you very much for your help!
    I will try it out
  17. olskool

    olskool Well-Known Member

    Check your inbox. I also sent a pm.about this.

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