Geeky plan: Solar power supply IN THE CAR

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.

Categories: Travel

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  1. FES

    Why not just connect a fused cable to your car batter? Your alternator should put out 50-70A, more than enough to take care of normal car power requirements and your electronic equipment. If that is not enough, it will likely be cheaper to install an alternator that puts out over 100A.


    John Goerzen Reply:

    Because that requires a lot more work – drilling holes (to get it into the cabin), cable ties, watersealing, etc.


  2. Steve

    Cool idea. My thing though is, you are traveling in a car, with things going by to look at, and two kids in the back. Do you really think you are going to get any work done? ;-) Of course just because a geeky project may not be fully utilized is no reason not to do it.


    Anonymous Reply:

    This comment suddenly made me wonder: have you considered introducing your kids to OpenTTD? Given their affinity for trains, I strongly suspect they’d enjoy it.


    John Goerzen Reply:

    Replying to Steve – We’ll be on I-70 through western Kansas. Intentionally built through the most boring (and thus cheapest to construct) part of Kansas. Yeah it won’t be the same as at home and I may have some things to make up another time, but it works…

    thanks Anonymous for mentioning OpenTTD. I hadn’t known of it. I WILL be installing it!


  3. Blars

    Well, I have 450 watts of solar panels on the roof of my vehicle, which not only charge my house batteries (220 Ah) but also the starting battery durring the day. My alternator gets very little workout anymore. I’ve got 3g internet, but don’t use it when driving.


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