Have not measured the current draw properly yet but I did see that the board powers up with just the cell attached (no battery) without direct sun, bright daylight seems to be enough.
It will use 10x more when transmitting but that should be very brief.
So I left the thing running overnight on a 3300mAh battery, SOC at approx 98%, with solar input disconnected and it had dropped to 92% by morning.
The RAK was running in client mode with no screen, no WiFi module but BT is enabled (the only way I will be able to configure it once its up). Only 4 or so nodes visible during the test.
I think this is quite impressive compared with the ESP32 boards which would have eaten half the battery or more by now. Still, that 6% it is a measurable depletion of a large LIPO battery.
I might be tempted order a 5.5v supercap now and see how many minutes/hours it will run above threshold voltage from a full charge.
Some energy/capacity is wasted getting the cap up to 3.7+ volts but something like 60% of the energy from that charge is still available between 3.7-4.2v? Area under the curve at 1/2CV^2 Joules.
The Farads/storage though must be derated a lot for the same reason - difference from 4.2v to 5.5v is huge at 1/2CV^2 so you get maybe only 10-15% of the indicated capacity - and access to 50-60% of that as the usable voltage rangeā¦ 
Perhaps caps are a good way to trap & even out the solar wobbles and then transfer via charge pump to a small LIPO, something like 500-1000mAh?
I think Iāll just install the thing in a temporary way first and see if I can pick up new nodes, watch the battery state and then maybe take it down again for a second pass if I think of improvements.
Thatās a really good drain for 10 hours or so. I think the ESP32 will use far more, but to make better use of the charge in the capacitor Iām using a little boost converter to pump from 2v to 5v. With about 80% efficiency it means I make use of more of the stored charge.
Iām using two 250F caps so I expect to get at least 24-30 hours operation with a 4-6 hour charge period.
Waiting for parts right now.
Please let us know how your testing goes.
Boost convertor is a good idea - I have tried it with higher voltage systems (24v) but donāt have anything currently that goes down to 1-2v range. Will try to obtain some to play with now.
I do have a work-in-progress charge pump which was aimed specifically at energy harvesting (low loss) and might work here but I havenāt moved it from simulator to a real build yet - and it was intended for 24v so it could be difficult to get the same design down to this voltage range. Will look at that when I get more time.
So with continuous running since my last update, the 3300mAh battery dropped from 92% to 75%. Solar still disconnected.
I think I may need more cells, or more complexity for this.
Meantime my external node with omni antenna is happy to relay packets to/from other nodes but wonāt send out readable messages on LongFast/0 if connected to directly with the meshtastic client. I think there may be an issue with the default channel key and which does not show in the Android app. So Iāll need to bring it down from the roof and poke at it over USB again, or reflash it from scratch 
So I went to fetch the node from the roof and it was not on the roof 
last nightās wind won that battle.
It didnāt go far but the vertical antenna neck snapped and water got in so the HV3 might be a gonerā¦
ā¦looks like the silicagel packets were just enough to keep the board and battery dry(ish). Having second thoughts now about using batteries in this at all. Maybe joining the supercap club soonā¦
In the end, if its charge storage you want to maximize, batteries are probably the best way to go. Iām trying to build something that has 10-20 hours storage with a 3.5W panel, but will operate at -30C and the number of ārechargeā cycles is effectively unlimited as thereās no chemistry to depend onā¦
Sorry to hear about your node on the roof. I hope you can repair it.
For outdoor use you really need IP66/7 rated enclosures in Scotland. Theyāre a pain in the butt to seal properly, but worth it in the end. Another trick I use for outdoor installations is lightly spraying the PCB with artists sealant. (Used for āfixingā pastel chalks etc to paper to stop smudging.) That works pretty well too, but remember to avoid sm oscillators and metal-top IC packages, as these have little holes.)
I repaired the node and re-sealed it ready to reinstall.
It broke because it had not installed properly, was up for testing only (was not using the metal u-clamps) and was caught out by the change in weather - and being a bit busy/distracted with other stuff.
It is still too wild outside so I have propped it back on the upstairs NE window and it sees some of the same nodes, most of the time. Iāll leave it there until the weather improves. It should still be visible if you try another expedition
Meanwhile have fitted a weatherproof reset button on the box for the directional node and waiting for more parts to experiment more with the charging rates. Should have a small 10F cap and charge pumps to mess around with sometime next week.
Question for anyone who might know about thisā¦
Have encountered cases now where direct messages sent to a node are received by that node and visible on the nodeās local display but are not visible in the client/phone app connected to the node.
I have sent plenty of DMs to new nodes over the last weeks and very few ever acknowledge by message even if the software does appear to ack receipt. Since then I had feedback that messages donāt necessarily appear in the client app and therefore likely to get missed. I donāt know if this is a bug or config issue.
There is a relationship between the channel name and frequency slot, if LoRa freq slot is configured to =0 (auto slot mode).
My own nodes are set specifically to slot =1 for EU/868.
Does anyone know if the slot config affects handling of DMs? Each DM creates a unique channel name based on the receiver node nameā¦
I would think that if the node has received/decrypted it, the freq slot must be correct. However itās not clear what else could cause this problem.
I canāt find any details on this in the docs but any tips/clues welcome.
Is there a scottish meshtastic group anywhere?
Dunno if its what you mean, but thereās an msh/Scot.
Dunno about the East, but the West coast is definitely heating up. When I got my first Heltec there was hardly anyone on my map.
Got a couple of cases off eBay for one of my Heltecās and for the T-deck. Really good quality and means they have their own batteries and (hopefully!) better antennas. The Heltec case is using a Nokia style battery. While the T-deck uses 2 of the big 18650 batteries.
I need to redo my roof (Heltec) unit though. I power it using a USB battery bank. Tried a solar panel going to the USB battery bank, but the solar panel seemed to make the unit switch off for some reason? Iāll try again when itās not blowing a gale outside.
Not sure if itās people spoofing their locations, but Iāve got at least one person showing up in my Meshtastic app as being in Market Rasen and the message I sent them apparently sent successfully. Thatās about 375km. My piddly wee yagi canāt possibly be THAT good. 
I also have one of those nokia-type cases its decent but I have the version with the enclosed antenna not through-hole. Might modify it for a better antenna but Iām using it just now as a MQTT-only proxy.
but the solar panel seemed to make the unit switch off for some reason?
Thatās weird.
One of my heltec boards refuses to stay on even when plugged in USB and the charge light wonāt show. I think I destroyed the battery ADC or one of the charging related chips when messing about with it. The battery voltage reads 0 all the time so probably the ADC or whatever is in front of it. Might be a write-off.
Thatās about 375km. My piddly wee yagi canāt possibly be THAT good.
I have one node on my list which received from 101km near bordersā¦ which I figured must also be a spoof. Although the map pin shows it on a peak, high altitudeā¦
(my nodes are dml~, dmlR/K/T to the west of your map screenshot)
Note that if you have older firmware around 2.24.x the MQTT groups such as msh/Scot will not be the same group if you have 2.3.x onwards.
The firmware changed the sub-grouping from something like msh/Scot/2/c/ to msh/Scot/2/e/ and AFAIK they donāt communicate.
For now Iām keeping my MQTT node on 2.24.x until I see others moving their firmware up.
(my nodes are dml~, dmlR/K/T to the west of your map screenshot)
Yeah, we were chatting briefly. Iām RTj1/2/3 in G20
Some power banks have a minimum output current drain value of 80mA or so. They can turn themselves off if youāre below that drain value. Also with some of the older ones you canāt charge and use the battery at the same. Was the voltage from the panel 5v exactly? - If not that could be the issue.
Feels like NE is getting more busy now. Quicker than expected. Was in Dundee again the other day and my Heltec with standard antenna picked up 2 other users.
Plus spoke to a guy who lives on a hill near city and he was v interested to learn more about meshtastic
Currently in Newcastle and lots of nodes and bases around Sunderland
In case it is useful for anyone attempting outdoor/solar nodesā¦ although it does rely on standard Meshtastic map reporting over MQTT & WiFiā¦
The map linked below provides a lot of detail on map-reported nodes, probably as part of map report packets themselves or perhaps relayed from other nodes reporting neighbour nodeinfo (not sure which).
One of the interesting things you can find is telemetry on battery level over time
There is a lot of other info visible including heard/heard-from node records. Meshmap now also represents this (and more conveniently, although does not differentiate the two listening directions on a link)
On the downside, this map seems to reset the view on a brower page refresh. 
and opening the node info can be a bit laggy.
Yep plenty of activity.
Iām hoping to get 2 more nodes up soon in different locations. A second try at the one in the city centre next week and a new one in southside (but probably not before mid-may for that one).
Yep
Kinda. I like to say hello to new nodes that pop up, but hardly anyone answers.
Iām looking forward to the news headlines when someone comes across someones solar powered node. Several batteries, a bunch of wires, and a screen. All nicely sealed up in a tupperware tub.
BOMB FOUND HIDDEN UP TREE
[insert picture of passerby pointing to a tree]
While out at Forrestburn scouting repeater locations today, I picked-up Benarty Hill (Unattended) off to the northeast of my position. After checking it looks like this is high on a hill in Fife! Thatās 44.2Km.
Looks like the new antenna is doing the job just fine.
On to version 1.5 of my outdoor unit in the G20 area. Bigger tub, put the input on the edge of the tub, added a notch at the opposite edge for the solar panel wire, and stuffed the tub with silica gel packs (just for good measure) before closing it up.
Tried a solar panel going to the USB battery bank, but the solar panel seemed to make the unit switch off for some reason?
The problem seems to be when the sun is down, or low, the panel seems to be triggering the USB bank (and, thus, the Heltec) to keep rebooting. It was fine when the sun was out this afternoon and charged it from 10 to 17%. Very odd.
