Understanding Power Sources in a Camper Van

Understanding Power Sources in a Camper Van
Tips for using and optimizing your Class B RV’s power system.

By: Morgan Field

If you’re new to van life—or have owned your Class B for years—you’ve probably felt anxious about power at some point. Solar, batteries, inverters, alternator charging, generators … it can feel overwhelming, and most guides either get too technical or skip real-life usage.

I’m Morgan Field, a van life enthusiast traveling in my 2019 Winnebago Travato 59K. I travel with my pup-pilot Teddy, a pittie mix with a million-dollar smile and a zest for adventure. This article will give you a clear mental model for where your power comes from, how each source charges your batteries, what each is good at, and how to protect your system.

(Note: Every RV and van is different. Battery chemistry, inverter size, wiring, appliances, and driving habits all affect how a power system behaves. The examples in this article are meant to teach concepts—not provide exact instructions for every setup. Use this article as a learning tool, then take the time to read your operator’s manual and learn the numbers for your RV. That’s where real confidence comes from!)

The Big Picture: Your Camper Van’s Power System

Your RV’s power system is a team effort:

• Batteries store energy
• Power sources recharge them

No single system does everything. Solar, driving, shore power, and generators each play different roles. Knowing when to use each one protects your batteries, keeps systems predictable, and removes stress.

I started with the original AGMs and solenoid in my 2019 Travato, then upgraded to 300AH Lithium batteries with LiBIM for extended battery capacity and less battery anxiety. Now, the 2026 Winnebago Travato 59KL comes with 245-watts solar panels as well as the Winnebago Power MAX system, including 8.4kWh Lithionics lithium-ion batteries with dual alternator charging capability, Bluetooth control and pack heating system, the Winnebago x EcoFlow Power Hub Pro 5-in-1 power management controller, and touchscreen interface!

Overview of Camper Van Batteries

House batteries power your RV systems—lights, fridge, water pump, fans, etc.—while the chassis battery powers the engine. Confusing the two is a common source of stress.

AGM batteries are often healthiest when kept above ~50% state of charge. Slower to recharge, they offer less usable capacity and reduced off-grid freedom.

Lithium batteries can safely use nearly 100% of their capacity and recharge faster, making them ideal for extended off-grid stays. (Learn more about safely using your lithium batteries in cold weather, as well as storing them, in this interview with Lithionics.)

Voltage: A Quick Tutorial

Voltage is a helpful way to estimate how full your batteries are—especially for quick check-ins or when battery anxiety kicks in. Each battery chemistry has its own voltage curve (at rest):

• Example AGM: ~12.85V full / ~12.05V ≈ 50% / ~11.66V ≈ 20% / ~10.5V ≈ 0%
• Example Lithium: ~13.5V full / ~13.0V ≈ 50% / ~12.8V ≈ 20% / ~ 10.0V ≈ 0%

Voltage numbers on your display panels are most accurate when batteries are at rest. Charging, heavy loads, or solar will temporarily inflate or depress readings. Think of voltage as a temperature check—not the full lab report.

Beginner Tips: 

• Look up the voltage chart for your specific batteries and keep it on hand. 
• If you notice an ongoing pattern where your AGMs won’t hold a full charge after several days plugged in, it may be time to replace or upgrade.

Watts, Amps, and Amp-Hours Explained

Understanding what each metric answers is the foundation of managing your power system.

• Watts (W) tell you how much power an appliance uses right now.
• Amps (A) describe the flow of electrical current needed to supply that power.
• Amp-hours (AH) measure how much energy your batteries can store in total capacity.

Watts and amps answer the question: “Can I run this appliance?”
They describe instant electrical load. This matters for inverter limits, generator output, and shore power—and when deciding how many devices can run at once. A watts-to-amps calculator is invaluable here, or you can use a simple formula: Watts = Volts × Amps. For example, a device drawing 7.5 amps at 120 volts uses about 900 watts. To calculate amps from watts, reverse the formula: Amps = Watts ÷ Volts.

Amp-hours help answer the question: “How long can I run the appliance?”
Battery capacity determines total runtime. Thinking about how many amps per hour you have can help you see whether you’re gaining or losing energy over time—and how long recovery will take after a deficit.

Summary: The inverter, generator, and shore power determine what you can run; batteries determine how long.

Charging Your House Batteries While Driving Your RV

Your camper van’s alternator is often the fastest and most reliable way to recharge your house batteries—especially if you drive regularly.

Charging is managed through a connection between the chassis and house batteries:

• Solenoid (older systems): Connects the batteries when the engine is running. This is simple and effective with AGM batteries, but it can overheat or fail if house batteries are deeply depleted.
• BIM / LiBIM (modern systems): Actively regulates charging, protects the alternator, and prevents over-drawing the chassis battery. Some systems also allow charging the chassis battery from the house bank.

Warning Signs of a Failing Solenoid: If long drives no longer recharge your batteries or the fridge can’t run overnight, check battery levels. If house batteries consistently lag behind the chassis battery, the solenoid may need attention. AGM systems benefit from upgrading to a BIM; lithium batteries require a LiBIM.

Real-World Example:

With my 300AH lithium setup, driving recharges about 65 AH per hour—so an hour drive easily recovers a 65AH deficit.

Solar Power in an RV

Solar panels convert sunlight into electricity that recharges your batteries. They’re quiet, automatic, and excellent for low-to-moderate daily use—but real-world output varies.

Factors That Affect Solar Panel Output:

• Battery capacity
• Daily energy use
• Weather and sun exposure
• Time of year and daylight hours
• Location, shading, panel angle, and dirt

Real-World RV Solar Example:

A 200W solar setup can produce up to ~10 amps in ideal conditions. In reality, panels often operate at 70–80% of rated output due to angle, temperature, and surface conditions—bringing practical output closer to ~7 amps (~7 AH per hour).

Background loads—fridge cycling, propane detectors, inverter standby—can draw 0.5–4A continuously. On a sunny but intermittently cloudy day, this might leave a net gain of ~3 AH per hour. 

If you’ve already used 100 AH while boondocking, it could take 30+ hours of good sun to recover that energy. And once night falls, solar stops charging entirely.

This illustrates why backup charging sources—alternator/driving, generator, or shore power—are essential. Solar extends off-grid time, but it’s not a fast-charging solution. (Note: Keep panels clean to maximize output!)

Understanding RV Inverters

An inverter converts DC battery power into AC household power for your outlets. Anytime you want to run appliances without shore power or a generator, the inverter is what makes that possible.

Inverter Capacity Matters:

• ~1,000W: Laptop, TV, Starlink, low-watt appliances
• 3,000W+: Microwave, air fryer, higher-watt blender, and (with enough battery capacity) A/C

Real-World Inverter Example:

I have a 1,000W inverter, which comfortably powers my TV (20–100W) and Starlink (75–100W) at the same time—perfect for late-night movies or getting work done on the road. I also run my BougeRV 23 Qt mini-fridge (~30–60W) and a low-watt electric kettle (~300W) without much thought.

Practical Inverter Tips:

• Know which outlets are inverter-powered.
• Learn appliance watt draws (buy low-watt when possible).
• Turn the inverter off when not in use—it draws power even while idle.
• For longer off-grid stays, upgrade inverter size and battery capacity together.

Shore Power for RVs

Plugging in provides direct AC power and quietly charges your batteries. Most Class B vans are wired for 30 amps, but campgrounds may have 15- or 50-amp outlets. Dogbones (adapter cords) make safe connections simple. It is best to always use a surge protector to protect your power system. 

Real-World Shore Power Example:

A 30-amp van plugged into a 50-amp pedestal only draws 30 amps. A 15-amp outlet limits you to 15 amps, so you must be selective about appliance use. (If you are thinking about plugging your van into a house outlet and looking for best practices for “moochdocking,” read more about that here.)

RV and Camper Van Generators

Generators provide reliable, on-demand power and let you run high-draw appliances without worrying about inverter limits. My generator supplies ~23 usable amps, so I usually run one major appliance at a time—if the microwave is on, the A/C goes off briefly.

They’re also efficient for recharging house batteries. Mine adds roughly 35 amp-hours per hour, making it easy to calculate runtime and recharge needs—no guesswork, just math.

Real-World Camper Van Generator Example:

I use my generator most often when traveling with my dog or working remotely—mainly for temperature control and dependable power when running errands or working without hookups. I also use it for higher-watt appliances like my blender or hair dryer. While I may eventually expand my lithium bank or inverter for quieter off-grid use, I love having a generator. It eliminates single-point charging failures and adds real peace of mind.

Tip: The generator requires house battery power to start; if batteries are too low, shore power may be needed first.

Final Takeaway on Powering Your Class B Van

There’s no perfect power setup—only what fits your travel style. If you prefer campgrounds, you may need minimal batteries and inverter power; boondocking requires larger capacity and multiple charging sources. Understanding watts, amps, and amp-hours lets you predict draw and recharge times, protect batteries, and avoid overloads. Once you know your van’s ecosystem, your power system stops being intimidating—it supports freedom, not limits.

Wishing you joyous vanventures ahead!
—Morgan & Teddy (Follow along on Instagram @themorganfield or on Facebook)