[pct-l] The technique of charge a lithium-ion battery of DSLR camera by the solar panel

[James Vesely]

With some experimentation I have come up with a piece meal solar charge system it has a 5 watt (stated) panel and a prefab solar/USB charge circuit board with a 2500 Mah li-ion (stated) battery that weighs just over  10 oz.  and charges the battery at about 500 Mah (making it more like a 2.5 watt panel) in direct sunlight (it takes about 4-5 hrs of blue sky direct sunlight to charge the battery to 95%).     The system has not been used on the trail yet but it seems to work as predicted.
     
The system can be optionally charged from any 110 or 12 volt USB charge adapter as well as from the solar panel.
 
Because of heat losses and other charging inefficiencies I find I can charge my Samsung S3 with a 2100 Mah (which is probably only 1500 Mah) battery from about 25% to full charge before solar battery depletion.     

The USB cable is multi use in that it can be used to charge the battery on solar charger then reversed to charge your phone or be used in conjunction with a plug in USB adapter .  To save weight I have decided to use shrink wrap tubing to protect the battery and charge circuit board rather than a metal minty box.  I also found it useful to use a universal li-ion battery USB charger that’s slides into the USB port to charge my camera (or any) li-ion battery. 

The size of the li-ion solar battery is upgradable to a larger size and can be customized based on usage.   Due to the varying  sun exposure while walking it really doesn't make much sense in having a huge battery unless you want to charge it via 110 or 12 USB charger while in town.       A 2500 Mah battery is just about right for backpack mounted, while walking type charging and I based that on the fact that anything bigger might not get fully charged in day.   If you bring two cables it is possible to charge the solar battery and your device at the same time. 

The photo link below shows the charger and also has links to purchase the parts separately.   Note: I have bought several battery packs and most of them seem to overstate there capacities.  

The total cost of the parts without shipping comes to about $55 not including the USB cable and the solar panel USB modification in which I soldered a USB output  port to the back of the solar panel.  
The mod is not really necessary and the only drawback would be you would have to carry the extra weight of the additional cable.   

https://plus.google.com/u/0/photos/+JamesVesely/albums/6002188681269867409

Jim 


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-----Original Message-----
From: pct-l-bounces at backcountry.net [mailto:pct-l-bounces at backcountry.net] On Behalf Of Ryan Weidert
Sent: Friday, April 11, 2014 12:13 PM
To: Yoshihiro Murakami; pct-l at backcountry.net
Subject: Re: [pct-l] The technique of charge a lithium-ion battery of DSLR camera by the solar panel

I too have come across the inevitable, "my camera requires rechargeable lithium batteries and I plan on draining more than one" situation. My solution is to go to Amazon and buy 3 or 4 (or more) cheap ($5-10) knockoff batteries, fully charge them before the trip and just carry them. In the end they weigh less than the solar charger and charger docking station needed to recharge them. I've never had the batteries damage my cameras (Canon 7D and Rebel XTi or s100) and only one has ever failed after a year or two after use. They may not last as long as the manufacture battery (probably on order of 80-85% of OEM capacity) but do the trick without hurting the wallet. Plus you'll have more batteries as backup for other trips! On my last speed attempt, I had my mail drop person charge a battery then put it in my resupply box, thus I could get charged batteries and not have to carry charging gear. The other battery goes into the hiker box (is cheap enough to leave) and off you go.

cheers,
Tuna Helper


On Fri, Apr 11, 2014 at 6:31 AM, Yoshihiro Murakami < completewalker at gmail.com> wrote:

> A few PCT hiker may need such a technique. The easy way is to bring 
> two or three batteries, and to charge them at the hotels. But, I would 
> like to stay in wilderness for 20 days in this summer ( I will 
> purchase a food drop service, and stay in the wilderness ). And I 
> changed my main camera to Pentax K-3, which need a lithium-ion 
> battery. Therefore, I have tested several technique.
>
> 1. The recommended technique by the maker. I am using GoalZero Nomad 7 
> solar panel. In this case,  the combination with the lithium 
> re-charger Shelpa 50 was recommended. But Shelpa 50 was very expensive 
> and heavy ( 500 gram ) Therefore, this technique is unrealistic.
>
>
> http://3.bp.blogspot.com/-81k7VKW--g4/U0XPwt37dfI/AAAAAAAAW-M/ygMlTdCo
> Pnk/s1600/sherpa-50-v2-solar-ac-kit_05.jpg
>
>  2. Use of 12 V DC output.
>
> GoalZero has 12 V DC output, and there are many chargers which have 12 
> V DC input using cigar socket. Therefore, I connected the 12 V DC