Solar powered PDA battery / charger (Noob needs help!)

[fredkadet]

Hi all,

First off, great forum! Am a noob at electronics and schematics and would really appreciate some help starting my solar panel project.

I hope to be doing some serious hiking next summer in Belarus and Poland but need my Samsung Galaxy Tab phone for GPS assistance (I know its big but need to take it to do some internet-related things also). I will need to charge it somehow whilst hiking so naturally a solar charger looked like a good solution to charge the 4000mAh battery in my phone. The problem is most portable solar chargers with battery will output 5v at about 0.5A current. Assuming I can find one with a 4000mAh batterypack it would take more than 8 hours to fully charge (correct?). This is most likely too long as I'd probably need a full charge every day.

So maybe it is possible to build a 1A solar charger with battery myself using things from ebay. Ive been looking at other tutorials but haven't been able to find a comparable project. I have though found the following parts:

- 5W, 12volt, 0,35 ampere solar panel,
- a 3.7v 4000mA replacement battery flatpack for Galaxy Tab to store power,
- USB connection to deliver power form battery to phone.

I'd love to get 2A output but have learnt this is unrealistic using a 5W panel (5W = 12V x 0.35A, so 5W = 5V x 1A should be doable reducing the chargetime).

I know i need to regulate the power from the panel and protect the battery from overcharging/discharging. Let me know if you can guide me in my quest and I'll buy you a beer!!

Cheers, Fred

EDIT: My phone charges at 500ma through USB and 2000ma through wallplug. I believe USB cannot deliver more current, is this correct?

 

[blueroomelectronics]

You'd probably be better off buying a panel with electronics made for hiking. Another choice is a USB power pack like the Hypermac products which have enough juice to charge an iPad 10W. They're also far more durable & portable than a solar panel solution.

 

[fredkadet]

Hi blueroomelectronics,

Thanks for your reply. A hypermac looks interesting but is mighty exepensive! As far as a hiking solar charger I cant find a portable one outputting 1A and storing ca 4000mAh.

 

[blueroomelectronics]

And you probably wont in a hiking package and if you think the Hypermac devices are expensive (they aren't, I use one with my MacBook) a solar solution as you've described will be priced like the stars. Flexible / durable solar panels are not cheap and usually not terribly powerful. You also want battery storage that's light enough to carry once again not cheap.

If it were me I'd simply carry around a Hypermac pack and charge it whenever I was in town. How often do you plan to use the Galaxy Tab? Charging a 15WH battery will take a long time with a small solar panel on a clear sunny day and that's only if it's pointed at the sun. Also note panels are generally rated for use under ideal conditions at low latitudes. Your 5W panel will be much lower in practice.

edit: The Hypermac is overkill for your Tab there are several less expensive battery packs that will work with your Samsung. Can't recall the name of one I saw recently but they were about $65 CDn for the kit.

The most portable solution would probably be a couple of spare Tab batteries and the charger.

 

[fredkadet]

Hmm. Ok, thanks anyway