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blog:2026-08-25:va7ilo_meshcore_repeater_build [2026/08/30 10:37] – va7iloblog:2026-08-25:va7ilo_meshcore_repeater_build [2026/09/14 19:14] (current) – va7ilo
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 First off, the Heltec V4 has a built-in solar input so this could be used to interface it (using caution that the maximum voltage is 6 V) the downside of doing this is the charging current is maximum 500 mA and there is a risk that even a 5-volt panel might have an open circuit voltage that exceeds this 6 V maximum. In light of this I opted for a charge controller board rated at 3 amps, which takes advantage of the maximum charge that the solar panel can put out as well as over voltage protection etc.… First off, the Heltec V4 has a built-in solar input so this could be used to interface it (using caution that the maximum voltage is 6 V) the downside of doing this is the charging current is maximum 500 mA and there is a risk that even a 5-volt panel might have an open circuit voltage that exceeds this 6 V maximum. In light of this I opted for a charge controller board rated at 3 amps, which takes advantage of the maximum charge that the solar panel can put out as well as over voltage protection etc.…
 The board has ntc pads on it for freeze protection and high battery temperature protection (by default on the variant I have this is bypassed with a surface mount 10K resistor, which could be removed and pads soldered to with the yellow or white wire from a battery that has an onboard 10K thermistor or alternatively adding a thermistor against the battery casing if it doesn’t have this) this could be useful to use but I opted to not bother with it as I decided to use a separate freeze protection method, the charging board has overcharge and over discharge protection, the battery has its own high temperature and other protections too. The remaining consideration that is left is freeze protection (not sure if this is overkill or not if I insulate things somewhat but better safe than sorry) so I ordered some small temperature switches from Aliexpress that are normally closed 0 degree centigrade rating, these should open up if the battery temperature reaches 0 degrees and halt charging until it warms up again, I will open one of the lines from the solar panel and install it there and put it against the battery case with some Kapton tape. I chose this board originally for the NTC part but abandoned that idea as I preferred to have the freeze switch instead, I could have chosen a different board for my purposes due to this. I think it is better to go with minimum 3A board as I tested this one by plugging it into a usb charger and it drew 2.6A at first charging the battery so if you want to pre charge the battery good to know, as charging progressed it did switch to a much lower charging current. The board has ntc pads on it for freeze protection and high battery temperature protection (by default on the variant I have this is bypassed with a surface mount 10K resistor, which could be removed and pads soldered to with the yellow or white wire from a battery that has an onboard 10K thermistor or alternatively adding a thermistor against the battery casing if it doesn’t have this) this could be useful to use but I opted to not bother with it as I decided to use a separate freeze protection method, the charging board has overcharge and over discharge protection, the battery has its own high temperature and other protections too. The remaining consideration that is left is freeze protection (not sure if this is overkill or not if I insulate things somewhat but better safe than sorry) so I ordered some small temperature switches from Aliexpress that are normally closed 0 degree centigrade rating, these should open up if the battery temperature reaches 0 degrees and halt charging until it warms up again, I will open one of the lines from the solar panel and install it there and put it against the battery case with some Kapton tape. I chose this board originally for the NTC part but abandoned that idea as I preferred to have the freeze switch instead, I could have chosen a different board for my purposes due to this. I think it is better to go with minimum 3A board as I tested this one by plugging it into a usb charger and it drew 2.6A at first charging the battery so if you want to pre charge the battery good to know, as charging progressed it did switch to a much lower charging current.
 +
 +Another thing worth noting, is using a custom firmware tuned to ultra low power consumption like EasySkyMesh, below is a link to a separate article I am writing (bit of a work in progress), an excellent way to go for a solar node to really bring the draw down incredibly. Actually EasySkyMesh has affected another hardware choice, I was going to put a voltage monitor circuit to ground out the RST pin when the voltage dropped too low to prevent brown out boot loops, but this firmware virtually eliminates this concern so another advantage.
 +
 +[[..:2026-08-29:easyskymesh_firmware_for_meshcore|EasySkyMesh Firmware for Meshcore]]
 +
  
 [[https://www.amazon.ca/dp/B0FFS9WXQG?ref=ppx_yo2ov_dt_b_fed_asin_title]] [[https://www.amazon.ca/dp/B0FFS9WXQG?ref=ppx_yo2ov_dt_b_fed_asin_title]]
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-<fc #ff0000>(I removed the details about installing this temporarily as I will need to give a better explanation on how to install it and with which firmware, GPIO3 and GPIO 4 work well for EasySkyMesh for instance after remapping but not the stock MC firmware, I will add this back with more details later).</fc>+<fc #ff0000>(I removed the details about installing this temporarily as I will need to give a better explanation on how to install it and with which firmware, GPIO3 and GPIO 4 work well for EasySkyMesh for instance after remapping but not the stock MC firmware, I will add this back with more details later). Latest update, I actually am going to remove the clock module as it doesn't seem to be capturing the time correctly anyways. Since I am using EasySkyMesh firmware, I will put the GPS module back as it is off something like 99% of the time with this firmware so the overall draw is miniscule.  </fc>
  
  
blog/2026-08-25/va7ilo_meshcore_repeater_build.1788111423.txt.gz · Last modified: by va7ilo