Project Logs

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• V3

  Frank • 11/01/2025 at 02:50 • 0 comments

  After running this thing a few times, I noticed that it kept turning off. My best guess is that there was some kind of resettable thermal fuse somewhere near the battery.

  I also noticed that I just wasn't getting appropriate battery life. 

  I've purchased a Heltec t114 now, no screen or GPS and have had the unit running continuously for 3 days in overcast conditions (with westerly sun, 1/2 day of solar) and in with the solar panel in vertical orientation at home and think I've for the right setup for a solar node I can release into the wild in Newcastle, Australia.

  I noticed that the case was ever so slightly too narrow to accommodate the t114, so I've released a V3 of the design which is 3mm wider.

  I was also getting delayed trying to be able to print the case in ASA, but decided to just use PETG instead which will give me better heat resistance than the PLA in the prototypes.

• V2

  Frank • 09/30/2025 at 10:51 • 0 comments

  I really wasn't very happy with the first version, the SMA connector was coming out the side and was hitting the mounting bracket which was super annoying. I also screwed the back in with the antenna a bit loose. It was just all bad. Plus the battery kept running out because it's an Heltec V3!

  I quickly went back to the drawing board making the following changes to the cover design:

  - Change the orientation of the SMA connector

  - Change the wiring channel to be full depth to simplify support printing

  - Change the diameter of the SMA connector hole AND add a hex slot to prevent rotation

  3D model

  The assembly

  The display can be seen glowing through the case.

  Showing the whole device in flat position

  Before doing up the case

• Y-Cable construction

  Frank • 09/26/2025 at 12:10 • 0 comments

  I was able to build up a working Y-cable from the JST connectors and a short piece of two-core wire, I recommend a slightly smaller gauge than what I used as it was a squeeze to fit the bridging wire AND the Heltec V3 battery connector wire into the same crimp!

  BOM for the y-cable:

  - Short length of two-core wire 28awg recommended?

  - A JST connector pair - male+female and pins/sockets to match

  - Heltec battery connector and wire assembly

  Tools needed

  - Wire stripper (may be ok with careful knife work

  - Crimping tool

  - Exacto/Stanley knife for cutting back the insulation

  It was fairly easy to do with a crimping tool and a wire stripper. Care had to be given to ensure that pins had the correct orientation and that the polarities were also correct. As you can see my Heltec V3 powered up first go, indicating that I had adequate electrical connection and correct polarity, that said I'm yet to test out the charging circuit from the solar panel, I'll hopefully be able to try that tomorrow as I've also designed a quick first version of the battery cover replacement!

  Housing design

  The first version of the battery cover housing has been designed roughly and hopefully I can fit everything in and get a good seal onto the solar light case. 

  See https://cad.onshape.com/documents/76e104354e5fddc8aa51a2b6/w/b3a054152d103447e98b6e61/e/a5768d73274f489974acbf2b?renderMode=0&uiState=68d6828ed2255ab5c01ea3dc

• battery cover test fit

  Frank • 09/11/2025 at 20:45 • 0 comments

  Did a test fit yesterday of the first version of the battery cover and was generally happy with the result although it made a mistake on the notch depth which was easily rectified in the model.

• Modelling 1

  Frank • 09/11/2025 at 11:19 • 0 comments

  Just spent the evening modelling up the existing battery cover, so I can check dimensions before I grab a copy and modify it in CAD.

  I'll do a test print now and see how my measurements are.

  The model in OnShape.

  The model in OrcaSlicer before printing

  Should take just over 30mins to print on my Flashforge Adv 5m in PLA, though I probably won't use PLA for the final build for thermal reasons.

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