The off-grid battery bank directory — sizing tables, wiring guides, and real cost breakdowns. Updated nightly. No fluff, no 3,000-word introductions.
| Daily use | Typical load | 12V bank | 24V bank | 48V bank | Est. cost* |
|---|---|---|---|---|---|
| Weekend cabin | 1.0 kWh/day | 105 Ah | 52 Ah | 26 Ah | $450–700 |
| Van life (light) | 1.5 kWh/day | 160 Ah | 80 Ah | 40 Ah | $700–1,100 |
| Van life (full) | 3.0 kWh/day | 315 Ah | 160 Ah | 80 Ah | $1,400–2,200 |
| Small homestead | 5.0 kWh/day | 525 Ah | 265 Ah | 130 Ah | $2,300–3,600 |
| Full off-grid home | 10 kWh/day | 1,050 Ah | 525 Ah | 260 Ah | $4,600–7,000 |
*LiFePO4 street prices, Q3 2026, DIY racks vs plug-and-play. Formula: Ah = (Wh/day × days-of-autonomy × 1.25 safety) ÷ system voltage ÷ DoD.
Start here: what size battery bank for an off-grid cabin (the full formula with worked 1–5 kWh/day examples) or how many batteries you need for van life. Comparing backup options? Our generator sizing calculator covers the wattage side, and the quick sizing table below maps daily use to Amp-hours at 12V, 24V, and 48V.
The full formula, worked 1–5 kWh/day cabin examples, autonomy days, and the AGM-vs-LiFePO4 DoD math.
Two 100 Ah batteries for most vans — worked load lists from weekend to full-timer, and when to jump to 24V/48V.
The 2,000W inverter rule, wire-gauge savings, and why going 48V saves $300+ on copper alone. Publishing tonight.
Cycle-life math at 80% vs 50% DoD, charge efficiency losses, and the break-even year most calculators hide. Publishing tomorrow.
Every component, every dollar, every mistake — a full bill of materials from a documented build. This week.
Balancing, fusing per string, bus-bar sizing, and the diagrams people actually need. This week.
Heated-battery options, low-temp cutoffs, and insulation strategies compared. Next week.
Buyer math, worked in full: off-grid cabin battery bank sizing · van life battery count · what size generator do I need.
Enter your loads, autonomy days, and voltage — get Ah, fuse size, inverter tier, and a parts list with 2026 prices. No email required.
A weekend cabin using about 1 kWh/day needs ~105 Ah at 12V LiFePO4 (or 26 Ah at 48V) using Ah = (Wh/day × autonomy days × 1.25) ÷ voltage ÷ 0.80 DoD. That is one 100 Ah battery plus headroom; a 3 kWh/day cabin needs ~315 Ah at 12V.
Two 100 Ah 12V LiFePO4 batteries (~160 Ah usable budget) cover a light 1.5 kWh/day van build: fridge, lights, fan, and charging. Full-timer vans at 3 kWh/day need ~315 Ah, typically three to four 100 Ah batteries.
A 2,000W inverter can pull ~175 A from a 12V bank at full load. Two 100 Ah LiFePO4 batteries in parallel supply that briefly, but sustained inverter use means size by daily watt-hours, not inverter rating — 3 kWh/day of inverter runtime needs ~315 Ah at 12V or 160 Ah at 24V.
A 12V compressor fridge draws 40–60 W at a 30–40% duty cycle — roughly 400–500 Wh/day. A 100 Ah LiFePO4 battery stores 1,280 Wh (80% DoD usable ≈ 1,024 Wh), so it runs the fridge about two full days with nothing else on the bank.
AGM can only cycle to 50% DoD, so a 105 Ah LiFePO4 cabin bank becomes 168 Ah of AGM for the same energy. Over 3,000–5,000 cycles vs 400–600, LiFePO4 wins on cost per usable watt-hour by year two or three in almost every sizing scenario.
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