May 4th, 2012
From the “might be geeky” dept…
For an upcoming car trip, we have to take my wife’s car (long story). I will be taking two large lead-acid batteries in the trunk hooked up to a solar panel in the rear window area and, of course, some electronics in the front seat. Why, you ask?
While she drives, I will be working via tethered 3G (conveniently reducing the number of vacation days the trip requires). This is Kansas, so signals are weak sometimes. I have an external antenna that hooks up to a signal booster. So I’ll be running a laptop, cellphone in “draw lots of power mode”, and a cellphone booster – at minimum. Measurements suggest that this combination could easily put me in range of the typical 10A limit of dash electronics. (And doesn’t even include the “nice to haves” of GPS, my handheld radio, and the amplifier for it.)
My car has a direct high-current link from the battery to the trunk to support the 100W amateur radio mounted there. It is pretty easy to tap into it and add a cable that runs to the passenger seat to run all this stuff.
Terah’s car… doesn’t.
So, I thought, what’s the easy solution? Well, my solar power system, of course! If I charge up a couple of the large batteries beforehand (just pop them and a few panels in the sun for a day), then put the batteries in the trunk, it will probably power my electronics for a whole day (enough for the trip we have planned), and I have already cabled them up to support the kind of current draw I’ll have. I’ll have to recharge the batteries at the destination, of course, so I’ll bring along a panel (no need to bring more than one since there will be plenty of time to charge).
Once I’m planning to take a panel along, I figured I might as well put it under the rear window so it can actually help charge the batteries as we go. The current drain will, of course, be larger than the 1A or so it can put out, but hey, who else drives down the interstate with an active solar panel in their car?
I can actually split the load between the batteries and the vehicle system too, so I do not need a continuous 10A draw on the batteries.
The sad part about this is I will probably never surpass a temporary battery system with a solar panel in terms of geeky travel.