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Re: Charging camera batteries at Resupply points? - & communications

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  • ptoddf
    Search ebay for solar phone chargers for the voltage of the battery in your phone or device. Query seller for compatibility if in doubt. Naturally you can get
    Message 1 of 4 , Jun 13, 2013
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      Search ebay for solar phone chargers for the voltage of the battery in your phone or device.
      Query seller for compatibility if in doubt.

      Naturally you can get 12 volt solar panel and run your phone or device car charger but direct charge makes more sense to me. 

      I just ordered a 2.5 watt panel that plugs into Samsung Android phone USB socket for about $22 mailed direct from China. They have 5 watts for about $32, too large/heavy. These are 5 volts maybe not what you need. I will have to prune the packaging/housing/straps to lighten it for backpacking. This panel has no battery of it's own unlike many for sale. 

      I'll post test results when I get it but I expect no problems. Direct ship from China has been fine takes about 10 days by mail.


      Sent from my Samsung Galaxy Express™, an AT&T LTE smartphone
    • Bill Hegardt
      I will just add my experience that voltage is only part of the equation. The solar panel needs to put out enough current so that the battery charger will
      Message 2 of 4 , Jun 13, 2013
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        I will just add my experience that voltage is only part of the equation. The solar panel needs to put out enough current so that the battery charger will function. The charger for my camera battery needs 12 volts, but a small 12 volt solar charger would not work, I had to return it and get a bigger one that put out enough current for the charger.

        - Bill


        On Thu, Jun 13, 2013 at 1:34 PM, ptoddf <ptoddf@...> wrote:
         

        Search ebay for solar phone chargers for the voltage of the battery in your phone or device.
        Query seller for compatibility if in doubt.

        Naturally you can get 12 volt solar panel and run your phone or device car charger but direct charge makes more sense to me. 

        I just ordered a 2.5 watt panel that plugs into Samsung Android phone USB socket for about $22 mailed direct from China. They have 5 watts for about $32, too large/heavy. These are 5 volts maybe not what you need. I will have to prune the packaging/housing/straps to lighten it for backpacking. This panel has no battery of it's own unlike many for sale. 

        I'll post test results when I get it but I expect no problems. Direct ship from China has been fine takes about 10 days by mail.


        Sent from my Samsung Galaxy Express™, an AT&T LTE smartphone


      • john_friend
        My camera batteries are 7.2V so they can t use direct USB or 5V output from the solar panel. I don t know of any way to charge them without a custom built
        Message 3 of 4 , Jun 13, 2013
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          My camera batteries are 7.2V so they can't use direct USB or 5V output from the solar panel.  I don't know of any way to charge them without a custom built charger other than using the 12V input to a charger I have.  I'm sure the voltage conversion loses some power, but I don't know how else to do it.

          The Goal Zero Nomad 7  has the 12v supply that would work with my charger and there seem to be enough other users who have successfully used the Nomad 7 while hiking to know that it should work.

          --John

          --- In johnmuirtrail@yahoogroups.com, ptoddf wrote:
          >
          > Search ebay for solar phone chargers for the voltage of the battery in your phone or device.
          > Query seller for compatibility if in doubt.
          >
          > Naturally you can get 12 volt solar panel and run your phone or device car charger but direct charge makes more sense to me. 
          >
          > I just ordered a 2.5 watt panel that plugs into Samsung Android phone USB socket for about $22 mailed direct from China. They have 5 watts for about $32, too large/heavy. These are 5 volts maybe not what you need. I will have to prune the packaging/housing/straps to lighten it for backpacking. This panel has no battery of it's own unlike many for sale. 
          >
          > I'll post test results when I get it but I expect no problems. Direct ship from China has been fine takes about 10 days by mail.
          >
          >
          > Sent from my Samsung Galaxy Express™, an AT&T LTE smartphone
          >
        • sanfran_rwood
          ... I wish you luck, but I encourage others to be more cautious. First, the batteries in your devices are probably Lithium Ion, which requires an input voltage
          Message 4 of 4 , Jun 13, 2013
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            --- In johnmuirtrail@yahoogroups.com, ptoddf <ptoddf@...> wrote:
            > Search ebay for solar phone chargers for the voltage of
            > the battery in your phone or device. Query seller for
            > compatibility if in doubt.
            >
            > I just ordered a 2.5 watt panel that plugs into Samsung
            > Android phone USB socket for about $22 mailed direct
            > from China. They have 5 watts for about $32, too large/heavy.
            > These are 5 volts maybe not what you need.
            > I will have to prune the packaging/housing/straps to lighten
            > it for backpacking. This panel has no battery of it's own
            > unlike many for sale.
            >
            > I'll post test results when I get it but I expect no problems.
            > Direct ship from China has been fine takes about 10 days by mail.

            I wish you luck, but I encourage others to be more cautious.

            First, the batteries in your devices are probably Lithium Ion, which requires an input voltage of 4.2V in order to charge. A solar panel that only provides 2.5V will need to have a step-up converter to get that voltage, meaning the amperage delivered drops correspondingly.

            The result could easily be that a charge cycle could inordinately long to actually recharge a decent-sized battery.

            Keeping a solar panel aimed more-or-less towards the sun is difficult while hiking at best. A solar panel that uses high efficiency monocrystalline cells will have higher current output, while one that uses amorphous cells will still work under more indirect or cloudly lighting situations. If you want to recharge during a zero day with the panel in full sun, one solution is better; if you want to recharge each day with the panel strapped onto your pack, the other might be better.

            Meanwhile, newer devices (some DSLRs, for example) are putting battery cells in parallel to deliver more voltage (7.4V), but that means recharging voltage is also doubled (8.4V), so either the solar panel has to be bigger, or once again a step-up converter will be necessary.

            There isn't a one-stop solution to using solar for extended backcountry hikes yet. Don't assume that a device will solve your needs, even if it is technically compatible.

            N.B.: I built a DIY recharger for my 2011 partial JMT (see it in my photo here: http://goo.gl/QmAqz ) -- the 6V 2W solar cell is from Voltaic Systems; Adafruit sells the adapter and has a tutorial here: http://www.adafruit.com/products/200 .

            I am not an electrical engineer (although I came close when I was studying computer engineering) so I would welcome corrections or refinements to the above advice.

            My experience with the recharger in 2011 led me to leave my GPS at home in 2012 and just carry spare batteries. Remember, you can include a set in your resupply, along with a padded envelope to mail home the exhausted set if you want to save ounces. Some folks have great results with solar recharging, but YMMV. It likely takes at least three of the following four: skill with electrical crafting; tolerance of extra weight; tolerance of high prices; and/or luck.
            --
            Richard
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