Solar Powered Relay Project

#1

Here are a few photos of my solar relay project with an external high capacity battery. I need to do some testing but the goal is to have the solar cell power the goTenna which in turn would charge the external battery. The solar cell is from Voltaic and is using their 5 VDC regulator. This should supply 5 volts to the goTenna. The battery and 5 VDC regulator are located in an otter box case under the solar cell in hopes to reduce the heat on both of them. I went with white PVC for the same reason to reduce heat on the goTenna unit. The very top cap will be left un-sealed to allow the unit to be turned on and off. I still need to poke some holes in the otter box case but by design they should not allow water in if I do the drip loops right.

This setup (not complete yet) is designed to allow it to be hung by rope, placed onto a tripod or a post / stick in the ground.

**Due to the picture formatting, you may need to click on the photo to see the whole thing.

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#2

Looks like a nicely designed set-up. I’ll be watching as I am in the early planning stages of putting together a relay node at my place. My plan is to also have it me moveable for travel, to mount to a vehicle or RV. I like the way you have this one set up.

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#3

and that’s a ‘naked GoTenna’ down in the PVC? Are you considering an antennae?

#4

I thought about it but I don’t have the test equipment to ensure I have a good match (Lo SWR) between the antenna and goTenna. At 1 watt you need good a match to get your limited power out.

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#5

you know, has anyone reviewed 3rd party antennaes for SWR. it would be nice to know which off the shelf units are closest.

I suppose that the quality of the soldering against the sacrifice GoTenna would matter as well.

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#6

That’s the issue, unless the goTenna unit has a way to tell what the SWR is you will never really know. Maybe an in line swr / power meter if you can find one that reads in the 0 to 1 watt range. The match is a combination of factors. Antennas might be labeled 900 mHz but they are often designed for a range of frequencies i.e. (The 900 mhz ham band is from 902 to 928 MHz. To truly match the antenna to the gotenna unit you need to know the exact frequency they use then adjust the antenna to match that.

#7

and I think the goTenna ‘hops’ within that bandwidth

#8

What is the behavior when the batteries die, the goTenna powers off, and then power is later restored by the solar panels charging the battery? Does the goTenna come back up in relay mode, or does someone have to notice that the device is off and then manually turn it back on again?

#9

If the goTenna powers off, then you must manually reboot it. You’ll find the battery is usually fully charged, but the GTM is off, when you crack open a node after loss of power.