![\"Three](\"https:\/\/schindlerengineering.com\/public\/wp-content\/uploads\/2026\/09\/three-builds.png\")
<\/p>\nThree things are on the truck this week, and they are not related except that
\nthey are all the same project.<\/p>\n
<\/p>\n
The tanks sit a few hundred yards up a hill, in trees. At the bottom you can
\ncatch a wisp of Wi-Fi. At the top, nothing usable. No hard wire — it is over
\na hundred yards of ground I am not trenching.<\/p>\n
The instinct is to push harder<\/em> at Wi-Fi. That is the wrong direction. Same distance, same trees, same antennas. The difference is physics: leaves are That trade is free here. I need about ten bytes an hour.<\/strong> I could So: a pair of 915 MHz LoRa nodes, an ultrasonic sensor looking down at the A kiosk. Home screen with everything worth seeing at a glance; tap anything and The important part is the left side of that diagram, not the right. Every source And it is wired to the hardware<\/strong> — RS485 to the inverters, The battery expansion hardware has landed: a 400 A DC breaker, 2\/0 welding I went to check what history the database had, so the kiosk would have months of The logger died on September 12 and nobody noticed for fifteen days.<\/strong><\/p>\n The database is fine. The schema is genuinely good — a hypertable with The thing that actually writes the samples<\/em> was never installed as a So I am about to build a beautiful dashboard for data I am not collecting. That Which makes the priority order obvious, and it is not the touchscreen.<\/p>\n O N W A R D<\/strong><\/p>\n Link budget computed from free-space path loss at 400 m plus published Three things are on the truck this week, and they are not related except that they are all the same project. 1. Getting water-tank data down a wooded hill The tanks sit a few hundred yards up a hill, in trees. At the bottom you can catch a wisp of Wi-Fi. At the top, nothing … <\/p>\n
\nThe answer is to go lower in frequency<\/strong>.<\/p>\n![\"LoRa](\"https:\/\/schindlerengineering.com\/public\/wp-content\/uploads\/2026\/09\/hill-link-budget.png\")
<\/p>\n
\nfull of water, and water eats 2.4 GHz. At 915 MHz it walks through. And
\nLoRa’s receiver hears down to −137 dBm<\/strong>, roughly 5,000
\ntimes fainter than Wi-Fi can manage, because it trades bandwidth for sensitivity.<\/p>\n
\nalmost send it by banging on a pan.<\/p>\n
\nwater, a small solar panel and a battery. No inverter — a typical inverter
\nidles at 5–20 W, which is a hundred times<\/em> what the radio draws.
\nIt would have been the largest load in the system by an order of magnitude, powering
\nnothing but itself.<\/p>\n2. A 27-inch touchscreen at the house<\/h2>\n
\nit opens the deeper view. Inverters, battery, tank level, temperature and humidity,
\nheat and cooling control, settings.<\/p>\n![\"One](\"https:\/\/schindlerengineering.com\/public\/wp-content\/uploads\/2026\/09\/kiosk-architecture.png\")
<\/p>\n
\nlands in one table<\/strong>, and the screens are just windows onto it. The
\ntouchscreen and the phone app read the same pipe, so they cannot disagree with each
\nother.<\/p>\n
\nEthernet to the Victron — not scraped out of a vendor cloud. That matters
\nbecause the clouds are slow and lossy: Victron’s HTTP endpoint hands you a reading
\nabout every 105 seconds no matter how nicely you ask, and the inverter portal answers
\na date query with today’s numbers regardless of the date. Both of those cost me a
\ncorrection on this blog already.<\/p>\n3. 1,000 amp-hours<\/h2>\n
\ncable, copper lugs. Ten 100 Ah modules, 200 A fusing each, a 900 A
\nbusbar, four 2\/0 runs back to the inverters.<\/p>\nThe unglamorous thing I found while writing this<\/h2>\n
\ngraphs to draw. Here is the whole of it:<\/p>\nsamples 1,456 rows 2026-09-10 -> 2026-09-12\nsamples_1min 110 rows 2026-09-12 -> 2026-09-12\nsamples_1hour 40 rows 2026-09-12 -> 2026-09-12<\/pre>\n
\nrollups at one minute and one hour, which is what makes a ninety-day query cheap.
\nPostgres and Grafana both run as proper Windows services and have been up the whole
\ntime.<\/p>\n
\nservice. It was run by hand once, and it died with the window it was running in.<\/p>\n
\nis the funny version. The real version is worse: history only accumulates
\nforward.<\/strong> Every day that collector stays down is a day of resolution that
\ncannot be recovered, at any price, ever. You cannot backfill a battery’s behaviour
\nat 3 a.m. on a night that has already happened.<\/p>\n
\n
\nfoliage attenuation figures, not measured — the real numbers get posted once
\nthe radios are on the hill. Everything else here is hardware that exists and is
\neither delivered or on a truck.<\/em><\/p>\n","protected":false},"excerpt":{"rendered":"