Meshtastic

Solar relays - best practice?

Hi, I’m looking at the feasibility of using Meshtastic to track rowing boats in use on a secluded river (for both performance and safety reasons). Due to the low elevations, proximity to water and non optimal sealed enclosures, node range is unlikely to be great.

I will therefore need a number of solar powered, ‘idiot proof’ repeater nodes I can deploy permanently along the river to relay back to HQ (and or support staff). Has anyone built such a device - ideally in a weatherproof enclosure with a solar panel attached (and if so - how big a panel for always on relay use?)

Maybe something like this, but ideally not quite so spendy! https://store.rakwireless.com/products/rak7205-lpwan-tracker-node?variant=27837945217124

Welcome @warwick!

Sorry for the late answer. There are quite a few threads regarding this subject. I did list the first ones that came to my attention:

You might also be interested in the router mode for your stationary nodes: “mesthastic --set-router”. Furthermore, make sure that the hop limit (max TTL) will not be exceeded from the farthest nodes.

Please, share your findings and test results from the field, as real world feedback is valuable for this project.

I hope you luck for the event!

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Ok, I am closer to doing some tests. I have 5 Groups of 2, 2.7V 500F super capacitors being charged off a 10watt solar panel. 16V, 0.59A. Goes into an MPPT controller set to output 5.6V 2Ah to charge the capacitors. Each cap has a protection board on it. Each pair is wired in series to make up 5.4V. Then wired parallel to get 5.4V 1250 Farad. From the capacitor it goes into a 5V USB Boost converter, which can provide 5V when the caps are at 1V.

I was hoping for some cold weather. But its 2 degrees C outside this week. Maybe February will bring some -40.

Right now the sun comes up by 0900 and is setting around 1645. I was able to measure 12v 4mA during a very grey overcast and possible snow day.

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Nice.

I’ve had some luck with solar lights.

This kind of stuff is one of those things where it is cheep or reliable, pick one.

If you don’t need them running 24/7, far from the equator (real winter) and don’t care if the batteries don’t keep up when you have several hours or days of cloud cover there are a lot of cheep options.

How many days do these events usually last? Would it be too difficult to pick up and drop off the repeaters and just charge the batteries?

Well, what I was going for was a repeater you can leave out at a high elevation. Maybe your Ice fishing or sledding. Typically its already -25C and toward February we will go down to -35C to -42C for 2 to 3 weeks before warming back up to -25.

I lost 4 Ridgid 4Ah drill batteries last winter. They get cold and 1 or 2 cells will die. I was able to save 1 pack. I opened up the case and charged just the 1 cell back up to a similar voltage to the others and its been ok. Even your cell phone will suddenly power down on low battery. Bring it in to warm it up and it has %60 battery still.

These super capacitors can be deep discharged and cycle times are high. We will see how it all works when it gets cold and long nights. I missed the shortest day of the year, but theres always next year.

I did consider ‘deployable’ rather than ‘installable’ but part of the justification is 24/7 tracking of lone athletes training as well as the events themselves. I get low temps will be an issue, but its UK so a ‘typical year’ worst case is ‘minus low single figures’ at worst.

Physically mounting equipment for optimal use can be a bit pricey too.

Are you willing to (or have access to) drive some kind of pole in the ground to have somewhere to mount an enclosure, solar panel, and be able to have good antenna and solar panel orientation? Are you worried about theft, or your device being considered unauthorized litter or worse? Some places get very concerned when they find strange electronics left unattended.

All of these can be overcome quite easily in this particular scenario - it’s remote enough that the local pond life on foot are unlikely to get close, and the boating folk in general will keep a look out once they know its safety related. Depending on node range (to be determined in real life tests) it may be that there are enough close buildings / light poles with electric that the power bit ceases to be an issue. I can’t find much online in terms of real life range with non ideal antennae at low river level working to non ‘high building / telecom tower’ gateways… hence the need for tests.

Cool.

Investing in an antenna tester and tuning your antennas can make a big difference.

Theres not many people out where I go. And now that its built, no sense it sitting in my Garage. Climb a tree and point it south. Maybe check on it once in a while if its not showing up. No cell service where I go.

If someone finds it. So be it. The panel was a spare. Just the cost of the Super Caps, protection circuit, MPPT. Ive lost higher cost items. Lost a car key in the bush once. That was a $600 woops