How many amp-hours do I need for van life?

For a typical van life setup: 100Ah LiFePO4 handles weekend use with a fridge, phone, laptop, and lighting. 200Ah handles full-time van life with the same loads plus a fan and more laptop use. 300Ah+ is for full-timers who cook electrically or have high-power setups. The formula: add up your daily Wh, divide by 12V, divide by 0.8 (DoD), then decide how many days autonomy you want.

Is 100Ah enough for van life?

For weekend use without induction cooking: yes. A 100Ah LiFePO4 (80Ah usable) holds 960Wh. A typical weekend load of 300-400Wh/day means 2-2.5 days of autonomy — enough for a 3-day weekend with some solar or a drive to recharge. For full-time living or if you cook electrically, 200Ah is the practical minimum.

How Many Amp-Hours for a Van? Calculate from Watt-Hours

Calculate battery capacity from daily watt-hours, required days without charging, system voltage and a deliberate usable-energy allowance.

"How many amp-hours do I need?" is the most common van electrical question. The answer is always: it depends on your loads. Here's the formula.

The calculation

Step 1: Daily watt-hours

List your loads, their wattage, and daily hours of use:

Load	Watts	Hours/day	Wh/day
12V fridge	50W avg	24h (duty cycle)	60Wh
Laptop	65W	4h	260Wh
Phone charging	15W	2h	30Wh
Fan (MaxxAir)	25W avg	6h	150Wh
LED lighting	20W	3h	60Wh
Daily total			560Wh

Add 15% buffer for hidden draws: 560Wh × 1.15 = 644Wh/day

Step 2: Convert to amp-hours

Wh ÷ voltage = Ah drawn per day 644Wh ÷ 12V = 53.7Ah/day

Step 3: Size for autonomy

How many days without charging do you want?

Weekend: 2 days → 107Ah drawn
Full-time: 3 days → 161Ah drawn

Step 4: Account for DoD

LiFePO4 at 80% DoD: divide by 0.8

Weekend: 107Ah ÷ 0.8 = 134Ah minimum → choose 200Ah
Full-time: 161Ah ÷ 0.8 = 201Ah minimum → choose 200–300Ah

Quick reference by use case

Use case	Loads	Recommended battery
Weekend, no cooking	Fridge, phone, lighting	100Ah LiFePO4
Weekend + induction cooking	Above + cooktop	200Ah LiFePO4
Full-time, no cooking	Fridge, laptop, fan, lights	200Ah LiFePO4
Full-time + induction cooking	All above + cooktop	300Ah LiFePO4
Full-time + remote work (desktop)	All above + high laptop/screen use	400Ah LiFePO4

Why solar matters for sizing

If you have 300W of solar producing 900Wh/day on average, and your daily load is 600Wh, your battery only needs to bridge overnight (8 hours) when solar isn't producing. That's a smaller battery requirement than if you were purely off-grid with no solar.

In practice: solar allows you to run a system with less battery than the pure autonomy calculation suggests — but you still need enough battery to get through a night and handle cloudy days.

The amp-hours vs watt-hours confusion

Amp-hours (Ah): Current × time. A 100Ah battery delivers 100A for 1 hour, or 10A for 10 hours, etc.
Watt-hours (Wh): Power × time. A 100Ah, 12V battery stores 1,200Wh.

When sizing, work in watt-hours (because appliances are rated in watts) and convert to amp-hours at the end. Mixing the two units without converting is a common mistake.

Worked planning check

For 800Wh per day, two days and an 80% allowance at nominal 12.8V, capacity is 800 × 2 ÷ 0.8 ÷ 12.8 = 156.25Ah. Add inverter losses if they are not already in the load total, then check current capability and the recharge plan separately.

The figures or dimensions in this example are explicit planning assumptions, not a product test or an installation specification. Replace them with your equipment data and actual measurements.

Planning questions

How much energy is in a 100Ah lithium battery?

At nominal 12.8V, the arithmetic is 1,280Wh. Delivered energy is lower after your reserve, losses and operating limitations; it is not a measured capacity result.

Can I mix battery brands or capacities?

Only with explicit manufacturer approval for the complete arrangement. Chemistry, voltage, age, current sharing and BMS behaviour can make a seemingly simple combination unsuitable.

Can lithium batteries charge in freezing weather?

Follow the exact battery’s permitted temperature range and heating conditions. Do not bypass a protective cutoff or infer charge permission from air temperature alone.

Use the free electrical planner to organise your daily loads and charging assumptions.