Camper Battery Capacity Calculator

Battery Capacity Based on Power Consumption

Low Power Consumption

If you use a gas absorption refrigerator, occasionally run the water pump, and charge your mobile phone or tablet—with limited travel during the colder months—a standard 95 Ah AGM battery is usually sufficient to provide 2–3 days of off-grid power.

Moderate Power Consumption

If you operate a compressor refrigerator, occasionally use the water pump, and charge your phone or tablet while traveling year‑round—and sometimes even watch TV—a 95 Ah AGM battery can typically power your system for one night of independence during winter. With a second, identical battery, you can extend your autonomy to 2–3 days.

High Power Consumption

High power consumption scenarios vary individually. Commonly, appliances like coffee machines, hair dryers, or even e‑bikes are mentioned. To estimate your consumption, you can use the following formulas:

• Formula: Power Consumption (W) ÷ Voltage (V) = Required Current (A)
• Then: Required Current (A) × Time (hours) = Battery Capacity (Ah)

Each appliance in your RV typically has a manufacturer‑specified wattage and voltage, allowing you to calculate your total power consumption accurately. For high consumption needs, a lithium battery is often recommended because it can be deeply discharged without damage—providing more usable capacity compared to AGM or gel batteries.

Capacity Based on Driving Behavior

Road Trip Profile

If you’re frequently on the road and your vehicle usually stays only one or two days at the same location—with intermittent shore power availability—you might prefer not to use external power cables at all. In cases of low to moderate power consumption, a second auxiliary battery is recommended. A drive of 2–3 hours is often enough to recharge your batteries for the next day or two.

Camper Profile

If you enjoy traveling south, setting up a chair and table, and relaxing for one or two weeks, you’ll likely have the option to use shore power. In such scenarios, solar panels can also be a good investment if you find you need more battery capacity or the flexibility to go off‑grid for a few days.

Solar vs. a Second Battery

Solar panels have the advantage of keeping your batteries charged whenever the sun is shining. However, if you experience a week of rain, drive during winter, or travel in northern regions (e.g., Scandinavia), solar may not fully charge your batteries. In these situations, adding a second auxiliary battery is often a better investment if you want to remain self‑sufficient for 2–3 days during low to moderate consumption periods before heading out on longer trips.

When Using Solar – How Much?

Often, it’s enough to find a sunny spot to recharge your battery during the day so that it is full by the evening. For beginners, a separate, compact, foldable solar module is recommended—one that you only deploy when needed, saving on installation costs. Tip: Order one inexpensively on Amazon. *Advertisement

Do I Need a Charge Booster?

In most cases, you will need a charge booster to fully charge your battery. Newer RVs (such as those from Pössl or Globecar) often come with a charge booster as standard, so you won’t need to worry about it. However, if you have an older model or plan to buy a used vehicle, it is advisable to purchase a separate charge booster.

In these situations, the alternator charges your AGM batteries as described above. A charge booster doesn’t necessarily charge an AGM battery faster—it ensures that the battery is fully charged. This is crucial for battery longevity, as AGM batteries should ideally only be discharged to 50% and prefer to remain fully charged.

Generally, the charge booster should supply 10% of the battery’s capacity in amperes. For example, a 100Ah battery requires a 10A booster—more than that could potentially damage the battery. We recommend the Victron Energy 10A model available on Amazon. *Advertisement

The same applies to lithium batteries, where a charge booster is also essential. Why? Read on for more details.