When you live in your RV, the battery bank stops being a weekend convenience and becomes your utility company. A single bad sizing decision means dead fridges and frozen pipes in February. The goal of a full-time build is simple: enough capacity to ride out cloudy days, an inverter-charger to run real 120V appliances, and redundant charging so you never fully drain.
Your daily demand
Full-timers run more than weekenders: residential 12V fridge (~50Ah/day), laptops and Starlink (~20Ah), water pump and lights (~20Ah), and often an inverter microwave or A/C on hot days (~80–120Ah). Budget 150–250Ah/day depending on climate and how often you lean on the inverter. That's 2–3x a casual camper's draw.
Sizing the bank
You want 2–3 days of autonomy without charging. At ~200Ah/day, that means a 400–600Ah bank for comfortable full-time living. Realistic builds look like:
- Modest full-time: 314Ah (one big cell) + disciplined solar.
- Typical full-time: 300–400Ah parallel bank.
- Heavy inverter use / A-C: 600Ah+ or a 24V system.
Run your exact loads through our bank sizing guide before committing.
12V vs 24V for big banks
Once you pass ~400Ah at 12V, the current gets punishing — thick, expensive cables and high losses. A 24V system halves the current and lets a smaller wire carry the same watts. If you're building a large full-time bank, read our 12V vs 24V guide before you buy; many full-timers jump to 24V above 600Ah.
Inverter-charger
Full-timing usually means 120V appliances. A 3000W inverter-charger (like the Victron MultiPlus-II) runs a microwave, coffee maker, and even a soft-start A/C, and recharges the bank from shore power when you're parked at a pedestal. It's the single most important "lifestyle" upgrade after the bank itself. See our inverter-charger comparison.
Three-way charging
- Shore power: the inverter-charger's AC input refills you in a few hours at a site.
- Solar: a 400–800W kit offsets daily draw and buys autonomy off-grid.
- Alternator (DC-DC): tops up while you drive between spots.
With all three, a full-time rig can stay powered almost anywhere. Our accessory guides cover every charger and controller.
Our full-time picks
- Best single big cell: HumsiENK 314Ah Mini — capacity and Bluetooth in a tiny footprint.
- Best scalable bank: WattCycle 300Ah Mini (parallel two for 600Ah).
- Best for extreme demand: LiTime 12V 400Ah.
- Best inverter-charger: Victron MultiPlus-II 12/3000 — 3000W inverter + 120A charger.
- Best solar baseline: Renogy 400W MPPT kit.
Shop the build
HumsiENK 12V 314Ah Mini (Bluetooth)
WattCycle 12V 300Ah Mini
Victron MultiPlus-II 12/3000
Build the whole system from our recommended gear list.
Is 300Ah enough for full-time?
For lighter full-time use (efficient 12V fridge, modest inverter) 300Ah can work, especially with solid solar. But if you run an A/C, microwave, or work-from-RV, step up to 400–600Ah. Our A/C on battery guide shows the real draw.
Should I go 24V as a full-timer?
If your bank is 600Ah or more, yes — 24V halves the current, slashes cable cost, and pairs naturally with larger inverters. Below ~400Ah, 12V is simpler and cheaper to wire. See 12V vs 24V.
Do I still need a separate charger?
No — that's the appeal of an inverter-charger: it both makes 120V and recharges the bank from shore power in one box. Add solar (MPPT) and a DC-DC for driving, and you've covered all three charging paths.
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