Funny you mention this... this Fall we got hit in the North East with a freak snow storm that took down a lot of lines (we had no power for several days, worst outage in my memory.) Verizon was up however so I could at least check my email and browse for updates on my phone and Xoom (which was indispensable during the outage!) I sort of took a different approach that may not be practical for what you want. I already a couple of AGM batteries from my other hobbies that are deep cycle that last a long time (and luckily kept charged thru charge controllers.) I jury rigged the car charger to the battery and charged both my cell and Xoom reliably during the whole outage. However I wanted to use the batteries also for the radio and other items so it will only last so long...
Now back to on topic... So for Christmas I got a 55w solar panel and a low-end solar battery charge controller that handles up to 65w or so. I also got a female car charger socket so I don't need to jury rig anything and it's plug and play for the car chargers. I put on Anderson Pole pole connectors (I love these, use them for a bunch of stuff) so it's all plug and play. No not portable, but the batteries will get me hopefully thru another outage.
-Mike
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