CPAP & Camping - Trip Report

What would I need to run the humidifier that is not too expensive?

Thu 4/12/2007 8:14 PM
Re: Solar charger setup and concerns

Here's my system.

I put a thirty-two amp hour sealed AGM battery in a tall ammo can, and
installed a waterproof cigarette-lighter type socket in the lid of the
can, wired to the battery terminals through a fuse. There is an
ensolite pad on top the battery to keep the terminals from shorting
out if the box gets turned upside down, but still leaving the
terminals accessible if needed.

Then I picked up a used ten watt solar panel from eBay, wired with a
plug to fit the socket on the top of the ammo can. This panel puts
about a half amp an hour back in the battery under ideal conditions,
so you might get 3-4 amps put back in each day, depending on time of
year, weather, shade or silt on the panel, and other factors.

I also carry a six foot extension cord for the 12-volt wire, in case I
need extra length from the panel to the battery -- depends on where I
want the panel to be mounted on the boat.

The waterproof plug in the lid lets me plug in the solar panel easily,
and still be able to quickly and securely disconnect for going through
big rapids if I want to.

It also means that when I need the power for a device, I simply unplug
the panel and plug in any standard 12-volt adapter without having to
open the ammo can. I can even invert to 120 volts to run up to about
90 watts of some other device without having to use a 12-volt converter.

The fuse protects the system for normal loads, like small battery
chargers, etc. If I have to use it on the ramp with my LVM pump (very
handy!), I open the box and clamp directly on the battery terminals to
avoid blowing the fuse with that high-amp load.

Lately, I've been thinking the easier way to go would be one of those
battery jump start gizmos you can buy for $40-50, and plug the solar
panel into its charging socket. But they would not be waterproof, of
course, so you'd have to be extra careful about securing the system
before risking any spashy conditions.

As to running devices straight off the solar panel during the day, the
current produced by the solar panel will be variable, as the angle to
the sun changes, clouds pass by, etc. And unless you have a very large
panel, the amperage is pretty small (my panel is about 14" square and
puts out 0.5 amps max and a lot less on average). That is why a lot of
folks have poor results. Instead, set it up to let the panel feed the
battery and run your device off the battery.

In my setup, to draw current for a device and feed the battery from
the panel at the same time, I could just use a splitter plugged into
the top of the ammo can -- one recepticle for the device and the other
for the panel's plug.

And by the way Wally and Marshall, there are some inarguably
legitimate uses for electricity on the river. Case in point, an
interesting rig I saw at Westwater a couple of years ago. A guy had a
CPAP breathing machine set up for 12 volts and was powering it off a
marine battery for his overnight trips. Wasn't gonna let a little
sleep apnea get in the way of his boating!!! And with the addition of
a moderately sized solar panel, he could have done a complete Grand
trip with that setup.