Voltage Sensor

Hello folks,

Currently planning to build a solar powered gateway setup. Plan is to use a Mikrotik LR8, a 100Ah Lipo, a SIM based 4g router and 100W solar panel. One part of this relies on knowing the state of the LIPO battery and if possible being able to read the voltage and transmit it evey hour over Lorawan. Before I go and build this, does any one have any experience building the above (or plans they might share…) and does anyone know of a reliable off the shelf lora device to do voltage monitoring?


A somewhat similar config was posted 2 or 3 summers back :blush: (Forum Search) with a RAK ODU with in built cellular backhaul rather than external router - uses less power overall, a smaller AGM battery, solar controller, passive PoE, and with a Dragino LT controller (allows up to 30v inputs) monitoring solar panel voltage and battery voltage. Note LT was inside the metal battery box and below the antenna to minimise the detected Rx level at GW….if using a plastic box then a simple trick like swapping antenna for a 50ohm load resistor achieves roughly same :wink: In a more complex builds one can use the LT’s relays/digital i/o to switch alternate/back-up batteries in and out…

No time to dig out details now or search myself but may look later/tomorrow…

The Dragino LHT65N can read an external voltage:

The measuring range of the node is only about 0.1V to 1.1V The voltage resolution is about 0.24mv.

It is not much but it might be of help.

I am no fan of the message that you see all over on this forum: “Do your own research” but in this case…

Here is another solution:

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Radio Bridge part of Multitech so should be reputable and relaible wrt LoRaWAN :slight_smile: BUT I hate it when companies put up a message on a product page like that saying “contact us for price and leadtime” - WTF are they afraid of?! I they think they are offering value they should be proud of it, stand by it and give at least an indicative price…1off, 10off, 1koff?! :man_shrugging: Then I can judge is it good enough value to commit further time looking and following through vs just handing them my contact details… marketing, got to love 'em! :slight_smile: (Disclaimer - am in sales, marketing & biz dev as well so…)

FWIW DigiKey indicate 1 off £120 (+VAT) to UK ($144), myDevices $145 (again expect +VAT), for this single channel/sensor device so guess I’ll stick with self builds or the more flexible/feature rich Drgno LT Controller :wink:

Most of the manufactures have a device that can have Analog Input, I am not sure of who you have access to to purchase from.

One thing to keep in mind is that your node is going to be close to the gateway. Your RSSI is going to be very high, this will potentially causa issues. You need to keep the RSSI below -60 → -65, this can be challenging.

Yep, hence my comments/advice above. Antenna is typically less sensitive directly above/below vertical, put in a box and potentially/in addition if you can have the solar panel aligned below the GW (or atleast the ant between ant and the battery/controller box as an additional absorber. One of my rigs with only a short mast above runs a little ‘hot’ but still reliable in the -40- -45 range, where others with even a couple more meters mast high and variuos ‘alignments’ range from -48- -65 all with a standard OoTB Antenna (2.1dbi?), where I am concerned and see excess RSSI on a couple of rigs I have used the SMA/50ohm resistor trick to good effect on close proximity sensors dropping 10-25db of signal as and where needed :slight_smile: YMMV!

If you go with a Mikrotik LoRaWAN Gateway, I at least would prefer an LtAP LR8, with this single device you got LTE and LoRaWAN coverage in one device, also WiFi and GPS if you have any need for that.

Hey Qmick,

Not sure how you intend to charge/control a large LiPo, do you mean a BMS managed 12volt Lifepo4?
I’ve used Victron Solar Charge controllers before at work to make a 140Ah based SLA system, the MPPT series 75.15 have a VE connect bus, and victron from memory appeared to make a special LoRaWAN node that connects via the Ve.director connector port on the Solar controller. Though I haven’t used It before, it would be worth considering / reading up on if it might suit your needs or if anyone has successfully used the endpoint node, it might not be TTNv3 useful though?
As Jeff-UK has stated at close range going to have to dumb down the RF signal :slight_smile:


Is that the same Victron that generates the most baffling and unsolvable issues posted here by people that are OK with other LoRaWAN products due to the very poor documentation?

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Found time to trawl for original post :slight_smile:

@Qmick - this was initial test build, since refined with decent set up and wiring and replicated multiple times since :slight_smile:

@tobiaslinkwitz note use of VE Solar controller :slight_smile: Used several now: very good - but have avoided complications around VE connect bus etc…just use as controller/charger. Sadly this very unit (since used in another field deployed rig) finally died a few weeks back - not investigated why, just swapped out, or looked at any warranty…should just still be covered I hope! (They ain’t cheap! :wink: )

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Ah yeah, honestly I didn’t do a forum read on the specific Victron VE node offering, was only giving a suggestion, but it does appear after further reading you are stuck with a Victron TTNv3 > intergration dashboard (on their own application?) so bit of a weird one.

But very good point, if there are many issues then probably not suitable, many other solutions just “work” as intended.

We are (at my IoT work place) in private projects still not using the IoT connectivity of the victron controller at this stage directly, we did however have a specific install with large batter and Solar powered/DC node where we could at least see “voltage” of the external SLA battery so that’s at least a good diagnostic instead of nothing.

I agree that the suggested nodes laid out before and after my comment are better suited to the job :slight_smile:


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