· Edition #7

The Busbar

A quiet news week, so we lead with a long-game data point: Marine How To's Rod Collins reports his DIY GBS LiFePO4 house bank has turned 17 years old and still tests at full rated capacity — a rare real-world marker on LFP calendar life. Power Queen ships a 24V self-heating trolling-motor battery, Victron documents a 1,400km off-grid pumping network on the Nullarbor, and the forums work through a bricked Deye inverter and a unified off-grid monitor. Honestly sized rather than padded.

Battery · The Lead

Marine How To's 17-year-old GBS LiFePO4 house bank still tests at full rated capacity

Rod Collins (MaineSail / Marine How To) reports that the DIY LiFePO4 house bank he built from GBS prismatic cells in 2009 — date-stamped May 2009, in service on his boat since early 2010 — has just turned 17 and still meets roughly 100% of its original rated capacity on a calibrated capacity test. By his earlier accounting the bank had passed 2,500 cycles, most around 80% depth of discharge, by 2023. It's one documented bank, not a study — but it's a rare long-horizon data point on LFP calendar life, and the practices Collins credits are the usual unglamorous ones: never park it full, no float, conservative voltages.

Real long-term data on LiFePO4 lifespan is scarce. Most cycle-life numbers come from accelerated lab testing or manufacturer marketing, and the field is barely fifteen years old in mobile use, so calendar-aging evidence at the decade-plus mark is thin. That's what makes Rod Collins' 24 May post at Marine How To worth reading: it documents his own DIY house bank, built in 2009 from GBS prismatic LiFePO4 cells (cells date-stamped May 2009) and in continuous service on his boat since early 2010, hitting 17 years old and — by his report — still delivering essentially 100% of its original rated capacity on a calibrated constant-current discharge test.

Collins (better known on the forums as MaineSail) is one of the more rigorous voices in marine DC, and he's been publishing capacity tests on this same bank for years — by his 2023 accounting it had passed 2,500 cycles, most of them around 80% depth of discharge. A pack that's both cycled that hard and aged that long with no measurable capacity loss runs against the intuition that lithium "wears out," and it's a useful counterweight to the 3,000–5,000-cycle marketing claims that we've watched independent testers struggle to reproduce on budget cells.

The caveats matter. This is one bank, built from cells that are two generations older than today's 280Ah/314Ah prismatics, maintained by an unusually careful owner — not a controlled study, and not a promise about the drop-in you bought last year. But the practices Collins credits are worth internalising precisely because they're boring: don't store the bank sitting at 100% state of charge, don't hold it on a float voltage, keep absorption voltages conservative, and don't bake it. None of that requires exotic hardware. We unpack why those habits map onto how LFP actually ages — calendar versus cycle — in this week's Background.

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Solar

Victron documents a 1,400km off-grid pumping network on the Nullarbor — 45kVA Quattro, 96kWh Pylontech, bore control over VRM

A Victron case study published 29 May details a remote sheep station on the Nullarbor Plain that runs entirely off-grid: a homestead system of three-phase 45kVA Quattro inverter/chargers, a 96kWh Pylontech lithium bank and a 44.28kW Trina array on SmartSolar MPPT RS controllers, plus three remote bore sites each carrying 24kVA of Quattros, 42kWh of Pylontech and 29kW of solar. The point of interest for the DC reader isn't the size — it's the architecture: Cerbo GX devices and VRM run pump control and tank-level monitoring across 1,400km of pipeline and 200-plus troughs, with generators that auto-start on battery state of charge.

Victron's 29 May case study covers an off-grid water-pumping network on a remote sheep station on the Nullarbor Plain, and it's a useful study in scaling the same DC building blocks van and boat owners use up to a station-sized job. The homestead runs three-phase 45kVA Quattro inverter/chargers, a 96kWh Pylontech lithium bank and a 44.28kW Trina array feeding a 48V bank through SmartSolar MPPT RS controllers. Three remote bore sites each add 24kVA (three 8kVA Quattros), 42kWh of Pylontech storage, a 29kW array, a Cerbo GX and a backup generator.

The interesting part is the control layer, not the nameplate. Each site's Cerbo GX reports to VRM, which handles remote pump control and tank-level monitoring through the GX digital inputs, and triggers automatic generator start on low battery state of charge or high consumption. The system supervises roughly 1,400km of pipeline feeding more than 200 drinking troughs across 118 paddocks — work that previously meant driving out to inspect bores by hand. It's a marketing case study and reads like one in places, but the engineering is legitimate, and the takeaway scales down cleanly: the same GX-plus-VRM logic that auto-starts a station generator is the logic that manages a van's shore-power changeover or a boat's genset.

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Battery

Power Queen ships a 24V 125Ah self-heating trolling-motor battery — 3,200Wh, IP67, dual-mode heating

Power Queen announced a 24V 125Ah LiFePO4 trolling-motor battery on 13 May: 3,200Wh, IP67-rated, with dual-mode self-heating (automatic during charging plus app-controlled preheat) and Bluetooth reporting of state of charge, health and estimated runtime. The company pitches it at 70–100lb-thrust trolling motors and quotes roughly 18 hours of runtime at a ~7A average draw. The press release is light on the specs that actually matter for sizing — continuous and BMS current, cycle life, weight and warranty were not disclosed — so treat it as a launch note, not a buying guide.

Power Queen — one of the cluster of budget LiFePO4 brands that share manufacturing lineage with LiTime and Redodo — announced a 24V 125Ah trolling-motor battery on 13 May. The headline figures: 3,200Wh of usable energy, IP67 water- and dust-ingress rating, Bluetooth that reports state of charge, battery health and an estimated-runtime figure, and a dual-mode self-heating system that warms the cells automatically during charging and can be pre-heated from the app before a cold-morning launch. Power Queen sizes it for 70–100lb-thrust trolling motors and quotes "up to around 18 hours" at roughly a 7A average draw.

A 24V pack aimed squarely at anglers is a sensible niche — higher-thrust trolling motors increasingly run 24V or 36V, and self-heating addresses the cold-water reality that LFP can't accept charge below freezing. The frustration is the spec sheet: the launch release left out continuous output and BMS current, cycle life, weight, dimensions detail and warranty terms — exactly the numbers you'd need to know whether it'll hold up to a full day on a 24V motor or what it weighs when you're lifting it into the bow. Until Power Queen publishes a full datasheet, this is a launch announcement rather than something you can size a rig around.

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The Background · Trend Piece

Calendar versus cycle: what a 17-year-old battery actually tells you about LFP life

The Lead this week is a single documented battery bank, which is exactly why it's worth thinking carefully about what it does and doesn't prove. A DIY GBS LiFePO4 pack that's 17 years old and still tests at full rated capacity is a striking data point — but to use it well, you have to separate the two ways a lithium battery loses capacity, because they behave very differently and the marketing on a battery box never distinguishes them.

Two clocks, running at once

Cycle aging is the wear you get from charging and discharging: each full cycle nudges capacity down by a tiny fraction, which is where the "3,000-cycle" and "5,000-cycle" numbers come from. Calendar aging is the wear that happens simply with the passage of time, whether or not you use the pack at all — driven mostly by two things the manufacturer rarely puts on the label: the average state of charge the cells sit at, and their temperature. A pack stored full and warm ages on the calendar clock noticeably faster than one kept partial and cool, even if neither is cycled. Both clocks run at the same time, and for most mobile and marine banks the calendar clock is the one that ultimately ends the battery's life, because a house bank spends far more hours sitting than it does actively cycling.

This is the lens that makes the 17-year result legible. Rod Collins' habits — never parking the bank at 100% state of charge, never holding it on a float voltage, keeping absorption voltages conservative, and avoiding heat — are precisely the levers that slow calendar aging. Sitting at a lower average state of charge dramatically reduces the chemical stress on the cell over time; skipping float means the pack isn't held at its most stressful voltage for years on end; conservative charge voltages reduce per-cycle wear as a bonus. None of it is exotic. It's the difference between a battery that's "topped up and ready" 24/7 and one that's kept deliberately a little hungry.

Why the cycle-life number on the box keeps disappointing

It also explains a pattern we've tracked in the independent testing world. When Panbo's Ben Stein ran budget LFP cells through real cycle testing, the 5,000-cycle marketing claims projected out closer to 3,000–4,000 — and that's the cycle clock alone, before calendar aging is even in the picture. The honest reading is that a quoted cycle count is a best-case ceiling measured under lab-friendly conditions, not a lifespan you'll see in a hot engine bay or a battery left full all winter. A pack rated for 4,000 cycles that you cycle 150 times a year would, on paper, last 26 years — but it won't, because the calendar clock will catch it first if you store it badly, or it'll comfortably exceed expectations if you store it like Collins does.

So the practical takeaway from one 17-year-old bank isn't "LFP lasts forever." It's that the levers most likely to determine whether your bank lasts five years or fifteen are largely in your hands and cost nothing: keep the resting state of charge moderate, don't hold it on float, keep it cool, and don't chase the last few percent of capacity on every charge. The cells have improved enormously since 2009. The aging physics hasn't changed.

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Community Pulse

What the forums are talking about this week

A cautionary firmware tale on r/diysolar this week: a 25 May post — "Anyone have the EU firmware for Deye SUN-5K-SG03LP1-EU? Flashed wrong version, MPPT now dead" — is the kind of thread that should be required reading before anyone flashes an all-in-one inverter. The owner loaded a non-matching regional firmware build and lost the MPPT input; recovering it means finding the exact EU image, which the manufacturer doesn't hand out freely. The lesson the replies converge on: region- and model-specific inverter firmware is not interchangeable, and "newer version number" is not the same as "correct build."

On the maker side, a 27 May r/diysolar post — "I built my own off-grid solar monitor because juggling three vendor apps drove me mad" — is a familiar itch scratched: one builder fed up with separate apps for inverter, BMS and shunt built a unified dashboard and is asking for feedback before launch. It's a recurring theme in the DC world — the data exists, it's just locked in three incompatible vendor silos. And a 28 May thread, "Jackery power stations lose pass through charging feature when connected in parallel", flags a genuine behaviour quirk worth verifying against your own units before relying on pass-through in a parallel setup — treat it as a forum report to confirm, not gospel.

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