Solar Kayaking

Early in our preparations (like six months ago!), I indentified the need for remote recharging. Unlike thru hiking, we have some electronics that we will really depend on. We must be able to get marine weather forecasts so we know when to stay off the water, we need the VHF radio in case of emergency, and we really do need a GPS in some of the confusing areas such as Ten Thousand Islands.  We will have more than one device for each of these critical needs, since we are dependent upon them.

Then there are other electronics, such as the digital camera, the tablet, and two cell phones.

How do we keep these charged?  There will be occassional town stops to resupply, but can we reliably find someplace to plug in seven devices, and then hang around for several hours?  And can we reliably minimize the use so that the batteries in all of them last up to eleven days between stops?



I started looking for solar charging.

I have owned little solar charges previously, and they were underpowered little gimmicks. I need this one to work. So I jumped in and quickly became overly analytical.  I made up a spreadsheet for every device, called manaufacturers to get the power usage rates and battery capacities, estimated hours of use, and basically went OCD. I figured out how much power (amp-hours) I needed to resupply each day.  Then I pulled down the solar radiation charts for Florida in January, and applied the derating factor for a flat solar panel instead of tilted or tracking.  I doubled that to allow for cloudy weather, and came up with the size panel and storage that I need.  Good stuff!

Then I started the search. Oh, and there is one other little consideration.  The panel and battery have to be small enough to mount on the deck of a sea kayak, and they have to withstand seawater washing over the bow and flooding over them.  That scared away the technical support folks at most of the solar companies!

But Goal Zero was outstanding to work with.  They were confident the panel would withstand sea water, though the solar battery pack would need to be in a water tight container. Working with them more, unfortunately their older devices lacked some things I need (such as the higher current rate for newer USB charging).  But they have a new model they expected to ship this Fall that is exactly what a need.  Except that it is a bit delayed and not in production yet.

Goal Zero technial support made a great suggestion - they hooked me up with design engineering as a beta tester!  With that, I was to get both a new panel and battery storage before they are available for purchase!  They arrived at the beginning of November and I set to work testing every device to make sure everything was compatible.  We have rather old cell phones and one would not charge. Goal Zero immediately mailed me an adapter, and viola everything works!

Next is to make it waterproof.  On the back of the solar panel is a small circuit board inside of a plastic case.  That won't work. Goal Zero gives me permission to open that up and apply epoxy to seal it against water. That looks good. Then on to the battery. That will be the interesting one.  It is a LiIon battery, and those get hot when charging (remember the recalls of the initial laptop batteries that caught fire?). I need to protect it from seawater, but not let it overheat. It will ride on top of the deck and needs to be shaded from direct sun.

We tried several watertight cases, such as Ottercase and Pelican. None were the right dimensions. The ones big enough for the battery were enormous, and also had thick walls which would retain too much heat.  We'll make a custom dry bag.  That can be the right size, not add unnecessary bulk, and will not retain heat as badly.  The bag is straightforward, except for sealing where the cable enters the bag. The first waterproof adhesive failed to cure, so I scraped it off and tried Aqua Seal.  That seems to do it.

As one more layer of back up, I made sure that the VHF radios can also accept alkaline batteries.  I got the optional AAA batteries tray, and loaded up on alkaline batteries. That provides another level of backup for the radios, GPS, and flashlights (though not the camera, cell phones and tablet).

I think we are ready.  Thank you Goal Zero!