Car & driving
How many Ah does a camper leisure battery need?
Amp-hours your camper battery bank needs from your devices and days off-grid — lead-acid vs lithium, plus solar to recharge.
Quick answer
Off-grid autonomy in a camper is a budget written in amp-hours: the fridge takes 25-35 Ah a day, LED lights a handful, phones and a laptop 10-15, the water pump almost nothing, and — the winter surprise — the diesel heater’s blower fan 20-30 Ah per cold night. A comfortable couple burns about 60 Ah a day at 12 V, and the battery bank must hold that times the days between hookups, divided by how much of the battery you’re actually allowed to use.
Battery bank needed
~240 Ah
- Daily consumption
- ~60 Ah/day
- Practical setup
- 3× 100 Ah AGM (or fewer, larger batteries)
- Solar panel to recharge daily
- ~240 W
Consumption profiles at 12 V: fridge (~25-35 Ah/day) dominates the minimal case; the diesel heater’s blower fan is the winter surprise (~20-30 Ah per night). Lead-acid batteries only give half their label before damaging cycles begin — that’s why 200 Ah of AGM equals ~110 Ah of lithium in usable terms, and why lithium wins on price per usable Ah despite the sticker. The solar figure assumes 4 good sun hours through a charge controller; double the panel for shoulder-season trips. An inverter running induction cooktops or kettles changes everything — that’s generator territory, not battery.
How it works
That last divisor is where chemistries earn their price tags. Lead-acid (AGM, gel) tolerates only ~50% discharge before cycle life collapses — a "100 Ah" AGM is really a 50 Ah usable battery. Lithium LiFePO4 gives 90% usable, weighs a third as much, and survives 5-10× the cycles: the sticker costs double, the usable amp-hour often costs less. The calculator sizes the bank for your profile and days, then adds the solar wattage to replace a day’s consumption with 4 good sun hours — pair it with a flexible solar panel for campers and an MPPT charge controller sized to match. One boundary to respect: induction cooktops, kettles and hair dryers through an inverter are generator-or-hookup territory; no reasonable battery bank cooks dinner for a week.
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Frequently asked questions
How many Ah do I need for a weekend off-grid?+
Two days at a comfortable 60 Ah/day is 120 Ah of usable energy: that’s 240 Ah of AGM (two 100 Ah batteries barely make it) or a single 150 Ah lithium with margin. If your camping is summer-minimal — fridge, lights, phones — a single 100 Ah lithium or 200 Ah AGM covers the weekend. Add any solar at all and the same bank stretches to nearly a week of sunny-season freedom.
Is lithium worth the extra cost over AGM?+
Run the honest comparison per usable amp-hour: a 100 Ah lithium delivers ~90 Ah usable for 2,000+ cycles; a 100 Ah AGM delivers ~50 Ah for 400-600 cycles. The lithium costs about double upfront and a fraction per cycle, plus it saves 15-20 kg of payload and charges faster. AGM still wins for occasional-use campers stored in freezing garages (lithium can’t charge below 0 °C without heated cells) and for the tightest budgets. For anyone camping regularly, lithium repays itself within a few seasons.
How much solar do I need to be self-sufficient?+
To replace a day’s consumption daily: watts ≈ (Ah × 12) ÷ (sun hours × 0.75 system losses). At 60 Ah/day and 4 good hours, that’s ~240 W — one large or two medium panels, feeding through an MPPT controller (20-30% more harvest than cheap PWM ones). Shoulder seasons halve sun hours, so double the panel or accept some driving days: the alternator is the underrated second charger, refilling 20-40 Ah per hour of travel with a DC-DC charger.
Why does my leisure battery die so fast?+
Usual suspects in order: it’s lead-acid and you’re counting the label instead of the usable half; it’s old (lead-acid loses capacity steeply after 3-4 years, faster if it ever sat flat over winter); there’s a phantom drain (alarm, USB sockets, the fridge on 12 V while parked — a battery monitor with a shunt finds it in a day); or winter heating is simply a bigger consumer than the bank was sized for. Storing any battery discharged through winter is the classic killer: leave it full, with a maintenance charger if possible.
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