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Last updated: October 8, 2026 (CT)
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Battery bank sizing for off-grid power systems.
The off-grid battery bank directory — sizing tables, wiring guides, and priced battery checks. No fluff.
| Daily use | Typical load | 12V bank | 24V bank | 48V bank | Est. cost* |
|---|---|---|---|---|---|
| Weekend cabin | 1.0 kWh/day | 260 Ah | 130 Ah | 65 Ah | $700–2,100 |
| Van life (light) | 1.5 kWh/day | 391 Ah | 195 Ah | 98 Ah | $1,050–3,100 |
| Van life (full) | 3.0 kWh/day | 781 Ah | 391 Ah | 195 Ah | $2,100–6,250 |
| Small homestead | 5.0 kWh/day | 1,302 Ah | 651 Ah | 326 Ah | $3,500–10,400 |
| Full off-grid home | 10 kWh/day | 2,604 Ah | 1,302 Ah | 651 Ah | $7,050–20,800 |
*Battery cost uses the 12V Ah in the row, because the 24V and 48V figures store the same watt-hours. Cost = (Ah × 12 ÷ 1,200) × the 12V 100Ah street price, rounded to the nearest $50. Low is Redodo at $269.99; high is Battle Born BB10012 at $799.00. Checked 2 Oct 2026. LiTime $302.39 and SOK $369.00 sit inside that span. Renogy lists $356.99 and was unavailable, so it is not an endpoint. Ah 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.
Sourced data table + CSV: trolling motor amp draw and battery sizing data
Direct answer: ~1 kWh/day weekend cabin with 2 days of autonomy → about 260 Ah at 12 V LiFePO4; 3 kWh/day → about 781 Ah at 12 V. Full formula and AGM vs LiFePO4 DoD on the guide.
Direct answer: light ~1.5 kWh/day van at 1 day of autonomy → about 195 Ah (two 100 Ah 12 V LiFePO4); full-timer at 3 kWh/day → about 391 Ah (four 100 Ah). Load lists on the guide.
The 2,000W inverter rule, wire-gauge savings, and how system voltage changes wire size. Planned — not published yet.
Cycle-life math at 80% vs 50% DoD, charge efficiency losses, and the break-even year most calculators hide. Planned — not published yet.
Every component, every dollar, every mistake — a full bill of materials. Planned — not published yet.
Parallel adds amp-hours and current at the same voltage. Series adds voltage and does not add amp-hours. The Battle Born manual stops at 48 V.
The BMS will not allow a charging current under 32°F (0°C). Absorption, float, and the heat-enabled model’s 28 W draw are on the charger page.
The spec table says 2–3% per month. The storage section says 4–5%. Storage temperature on that page is −10°F to 140°F. The 10 mA Bluetooth draw is a separate line.
9 to 11 ft-lb on the Battle Born terminal. 70 in-lb on a Lifeline M8 or M10 stud. The baking-soda step is the AGM manual, not the lithium one.
500 Wh plus 960 Wh is 1,460 Wh for one day. At 12 V and 80% DoD the formula is about 190 Ah, which two 100 Ah batteries cover.
The 1 kWh/day, 2-day cabin at 50% DoD is 416.7 Ah. Four GPL-31T batteries are 420 Ah at the 20-hour rate. Three are short.
Six steps for Ah = (Wh/day × autonomy days × 1.25) ÷ voltage ÷ DoD. The cabin example is 260.4167 Ah. The light-van example is 195.3125 Ah.
Ah, Wh, continuous discharge, weight, cold-charge or heating, and cycle rating copied from manufacturer pages. Accessed Oct 6, 2026. Missing cells stay “not listed.”
An 8-hour example night at the US Air Top 2000 STC high current is 30.625 Ah at 12 V and 0.80 DoD. The 120-second start is a separate fraction of an amp-hour.
Trojan’s flooded open-circuit table: 12.73 V is 100% and 12.10 V is 50% after a rest. That table is not a lithium chart and not a Lifeline AGM reading.
Buyer math, worked in full: off-grid cabin battery bank sizing · van life battery count · what size generator do I need.
Pick a device to fill the watts box, or type your own watts. Runtime uses this site's formula from the Ah card: runtime hours = (Ah × volts × DoD) ÷ load watts. It does not subtract inverter losses.
These presets use the maker's own published number, labeled by type. A graphics card figure is the card only and a CPU figure is the CPU only, not the whole PC, so add the rest of the system to the watts box yourself (the PC power supply label is the ceiling). A charger rating is the most that charger can draw while charging, so runtime at that number is the short end.
| Device | Watts | Wattage type | Source |
|---|---|---|---|
| NVIDIA DGX Spark | 240 | Power supply rating | www.nvidia.com |
| NVIDIA GeForce RTX 5090 card | 575 | Total graphics power (card only) | www.nvidia.com |
| NVIDIA GeForce RTX 5080 card | 360 | Total graphics power (card only) | www.nvidia.com |
| NVIDIA GeForce RTX 4090 card | 450 | Total graphics power (card only) | www.nvidia.com |
| NVIDIA GeForce RTX 4080 card | 320 | Total graphics power (card only) | www.nvidia.com |
| NVIDIA GeForce RTX 4070 card | 200 | Total graphics power (card only) | www.nvidia.com |
| AMD Radeon RX 9070 XT card | 304 | Typical board power (card only) | www.amd.com |
| AMD Radeon RX 9070 card | 220 | Typical board power (card only) | www.amd.com |
| AMD Radeon RX 9060 XT card | 160 | Typical board power (card only) | www.amd.com |
| AMD Radeon RX 7900 XTX card | 355 | Typical board power (card only) | www.amd.com |
| AMD Ryzen 9 9950X3D CPU | 170 | Default TDP (CPU only) | www.amd.com |
| AMD Ryzen 9 9950X CPU | 170 | Default TDP (CPU only) | www.amd.com |
| AMD Ryzen 7 9800X3D CPU | 120 | Default TDP (CPU only) | www.amd.com |
| AMD Ryzen 7 9700X CPU | 65 | Default TDP (CPU only) | www.amd.com |
| AMD Ryzen 5 9600X CPU | 65 | Default TDP (CPU only) | www.amd.com |
| MacBook Air (M5) | 60 | Charger rating (included 40W Dynamic Power Adapter, 60W max) | www.apple.com |
| MacBook Pro 14-inch (M5) | 70 | Charger rating (included 70W USB-C Power Adapter) | www.apple.com |
| MacBook Pro 14-inch (M5 Pro 18-core or M5 Max) | 96 | Charger rating (included 96W USB-C Power Adapter) | www.apple.com |
| MacBook Pro 16-inch (M5 Pro or M5 Max) | 140 | Charger rating (included 140W USB-C Power Adapter) | www.apple.com |
| iMac 24-inch (M4, four ports) | 105 | Max power consumption (Apple CPU Max figure) | support.apple.com |
| Mac mini (M6) | 70 | Max power consumption | support.apple.com |
| Mac mini (M5 Pro) | 145 | Max power consumption | support.apple.com |
| Mac Studio (M5 Max) | 200 | Max power consumption | support.apple.com |
| Mac Studio (M5 Ultra) | 385 | Max power consumption | support.apple.com |
| Mac Pro (2023, M2 Ultra) | 330 | Max power consumption | support.apple.com |
| iPhone 18 Pro or Pro Max (fast-charge adapter) | 60 | Charger rating (60W-capable adapter Apple lists for fast charge; sold separately) | www.apple.com |
| iPhone 17 (fast-charge adapter) | 40 | Charger rating (40W adapter Apple lists for fast charge; sold separately) | www.apple.com |
| iPad (included 20W adapter) | 20 | Charger rating (20W USB-C Power Adapter in the box) | www.apple.com |
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 and 2 days of autonomy needs about 260 Ah at 12V LiFePO4 (65 Ah at 48V) using Ah = (Wh/day × autonomy days × 1.25) ÷ voltage ÷ 0.80 DoD. That is three 100 Ah batteries; a 3 kWh/day cabin at the same 2 days needs about 781 Ah at 12V.
Two 100 Ah 12V LiFePO4 batteries cover a light 1.5 kWh/day van at 1 day of autonomy (about 195 Ah): fridge, lights, fan, and charging. Full-timer vans at 3 kWh/day and 1 day need about 391 Ah, four 100 Ah batteries.
A 2,000W inverter can pull 166.7 A from a 12V bank at full load (2,000 ÷ 12). Sustained inverter use means size by daily watt-hours, not inverter rating — 3 kWh/day for 1 day of autonomy needs about 391 Ah at 12V or 195 Ah at 24V.
This page does not publish a fridge wattage. Use measured daily watt-hours in the formula above. A 100 Ah battery at 12 V is 1,200 Wh nameplate, and the tables plan LiFePO4 at 80% depth of discharge (960 Wh usable).
Flooded lead-acid and AGM are typically limited to about 50% depth of discharge, so a 260 Ah LiFePO4 cabin bank (1 kWh/day, 2 days, 12V) becomes about 417 Ah of AGM for the same energy. The Battle Born 100 Ah manual lists 3,000–5,000 deep discharge cycles and 100% usable capacity for that lithium battery; these tables still plan LiFePO4 at 80% DoD. That manual does not publish an AGM cycle count.
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Matched to common bank sizes: 100 Ah LiFePO4 on Amazon · 2,000 W inverters on Amazon · battery monitors on Amazon
Related guides · Amazon picks (affiliate)
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Sources for the 2 Oct 2026 price checks and for depth of discharge and cycle life:
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Estimates follow industry-standard sizing rules and common safety margins. Always confirm with a licensed professional for final sizing.
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