RV Lithium Battery Guide & Calculator: Power, Capacity & Runtime Explained
Running an RV air conditioner on battery power? ABSOLUTLY, LEARN HOW HERE!
How to Choose the Right Lithium Battery for Your RV
Optimize Your RV Power Setup with Interactive Lithium Battery Calculators — Use our free, interactive Lithium Charge Time and Runtime Calculators to estimate how long your connected equipment can run on a single charge and how long it takes to recharge your 12-volt lithium battery.
Simply enter your battery’s amp-hours, charge rate, or power load in watts, and adjust the state of charge or depth of discharge to see real-time results. Designed for RV owners, solar setups, and off-grid power systems, these tools help you choose the right size for your lithium battery upgrade, chargers, and inverters for maximum efficiency and reliability.
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Pagosa Supply Co offers Lithionics & Epoch Lithium Batteries plus expert installation. Get Your Quote Today.
How to Use the Lithium Battery Calculators
Enter your battery capacity (Ah) — your total available energy storage. Use this to increase Ah to see how much more runtime you get by adding batteries. We offer 300ah, 320ah, 420ah & 640ah batteries, so use these amounts to see what your new found freedom can achieve.
Enter your load or charge rate (W) — total watts used or delivered.
Adjust your State of Charge or Depth of Discharge (%) — to simulate different use cases. We recommend never discharging more than 90% of your batteries. Lithionics has a built in “Never Die” feature, shutting the battery off at 10%. While it won’t harm the lithium batteries to go past that, needing to “jump start” the batteries back to life can be very inconvenient when boondocking.
View instant results for runtime or charge time based on your inputs.
Can You Run an RV Air Conditioner on Lithium Batteries? Here’s What You Need to Know
Yes—if the system is sized and configured correctly. Lithium (LiFePO4) battery banks excel at high power delivery with minimal voltage sag compared to lead‑acid. To run a roof A/C you must ensure:
- Inverter capacity: Enough continuous power and surge (compressor start‑up).
- Battery capability: Sufficient usable energy (Ah) and discharge current (A) without tripping BMS limits.
- Wiring & protection: Proper cable gauge, fusing/breakers, and ventilation.
- Charging configured for lithium: Correct voltage set‑points and temperature protections.
- Soft Starts Required: Keep in mind a soft start will be needed. Learn More
Undersize any one of these and you’ll see inverter overloads, BMS cut‑offs, or short runtimes.
Xantrex Freedom XC PRO 3000
- True‑sine inverter/charger designed for RV/marine. 3,000 W continuous with robust short‑term surge for compressor starts.
- Built‑in multi‑stage charger (up to ~150 A on 3000 model) with lithium profiles—set per your battery manufacturer.
- Best for Leisure Travel Vans, as it fits factory designated area.
Victron MultiPlus II 3000 W
- Premium inverter/charger (≈3,000 VA class) with strong surge capability and advanced features like PowerAssist.
- Excellent ecosystem and monitoring; widely used in RV and off‑grid builds.
- As with Xantrex, correct battery size, cabling, and charge settings are essential.
Why 3 kW? Typical 13.5k–15k BTU roof A/C units demand significant start‑up and running power. A 3 kW class inverter provides necessary headroom.
If you’re not powering the roof A/C from the battery bank (using shore power or a generator instead), a 2,000 W inverter or any quality inverter/charger/converter sized to your loads can work well.
- Size the inverter to continuous + surge needs for things like outlets, lights, fridge, coffee maker, microwave, etc.
- Critical: Configure the charger for lithium with the correct bulk / absorption / float voltages and temperature protections.
- Ensure the battery bank can supply expected current and desired runtime.
Lithionics
- High‑performance LiFePO4 with strong discharge capability—suited to running high‑demand loads like A/C.
- For A/C use at 12 V, many builds target ≥ 300 Ah usable capacity (or larger) plus a 3 kW inverter.
- Can use a single battery to power 3kW inverter. Some EPOCH, not all, require min of 2 batteries
Epoch
- LiFePO4 batteries with smart BMS, Bluetooth monitoring, and optional internal heating for cold‑weather charging.
- Great value and scalability; pair larger banks (e.g., 300–460 Ah+) with a 3 kW inverter for A/C support.
- *Essentials Series require minimum of two batteries for 3kW inverters
- Charge profile: Program inverter/chargers to the battery maker’s lithium voltages; disable equalize unless specified. Honor low‑temp charge limits.
- Battery current capability: Verify the bank’s continuous/peak discharge, and BMS trip points, exceed expected loads.
- Surge handling: A/C compressors have high inrush; 3 kW class inverters with solid surge margin are recommended. A soft‑start device can help.
- Wiring & protection: Use appropriately sized copper cabling, short runs, proper fusing/breakers, and good ventilation.
- Runtime expectations: A/C runtime is directly tied to battery size and recharge sources (alternator/DC‑DC, solar, shore).
- Voltage system: Match inverter to battery system voltage (12 V is most common in RVs).
- Monitoring: Use BMS/app or shunt‑based monitors for accurate state‑of‑charge and system health.
- Yes—you can run a roof A/C from lithium if you size the system right.
- For A/C: Aim for a 3,000 W inverter (Xantrex XC PRO 3000 or Victron MultiPlus II 3000) and a robust lithium bank (often ≥ 300 Ah at 12 V, larger for longer runtime).
- No A/C off‑grid? A quality 2,000 W inverter or similar is fine—just ensure proper lithium charge profiles.
- Correct wiring, fusing, ventilation, and monitoring are non‑negotiable.
Recommended Lithium Batteries for RVs and Off-Grid Power
If you’re ready to upgrade your setup, explore our premium LiFePO₄ lithium batteries.
We offer models designed for efficiency, durability, and high discharge rates perfect for mobile and stationary systems.
🔋 Lithionics 305Ah, 320Ah or 640Ah GTX Battery — Built like a tank, trusted, UL-listed power for luxury RVs
🔋 Epoch 300Ah or 460Ah— Bang for the buck, lightweight, reliable and rugged
Each battery includes an advanced Battery Management System (BMS), Bluetooth conectivity and self heating for safety, fast charging, and long cycle life.
Lithionics VS EPOCH Essentials Series for a 3000W Inverter System
A 3 kW inverter (such as a Xantrex 3000 XC PRO or a Victron MultiPlus II 3000 imposes specific electrical-current and battery-management demands for safe, reliable operation. When selecting a battery-bank configuration to pair with such an inverter, the discharge current capability and BMS (battery-management system) limits must be considered.
Click each section to expand details.
- Single-battery option: Lithionics 12.8 V 320 Ah — manufacturer supports inverters up to 3,000 W. Size cables and protection to full-load DC current.
- Two-battery option: Epoch Essentials 12 V 460 Ah — BMS is ~200 A continuous/~400 A (10 s) peak. For a 3 kW inverter (≈250–300 A DC draw at 12 V), parallel 2× to keep each battery within limits and handle surge cleanly.
| Parameter | Lithionics 12.8 V 320 Ah | Epoch Essentials 12 V 460 Ah |
|---|---|---|
| Nominal energy | ≈ 4,096 Wh | ≈ 5,888 Wh |
| Recommended continuous discharge | ≤ ~150 A recommended | ~200 A continuous (BMS) |
| Max/peak discharge | ≤ ~230 A max; ~1,200 A pulse (≈1 s) | ~400 A peak (10 s) |
| Inverter size guidance | Explicitly supports up to 3,000 W inverter | Use ≥ 2× batteries for 3 kW systems to stay under BMS limits |
| Series/parallel | No series (per datasheet); parallel per maker guidance | Series/parallel permitted per Epoch model guidance |
Values summarized from manufacturer specs and common installer guidance.
Xantrex Freedom XC Pro 3000 (12 V)
- Continuous power: 3,000 W (≈40 °C)
- DC current @ full load (12 V): ≈ 304 A (spec)
- Surge: ~6,000 W (≤ ~5 s)
- DC input range: ~10.1–18 V
Victron MultiPlus-II 12/3000/120-50
- Rated: 3,000 VA; continuous output: ~2,400 W (25 °C)
- Peak: ~5,500 W; Charger: up to ~120 A
- DC input range: ~9.5–17 V
- Approx. DC current @ 2,400–3,000 W (90–93% eff., 12–12.8 V): ~215–280 A (calc.)
Xantrex full-load DC current is from the datasheet; Victron DC current shown is an engineering estimate from rated power & efficiency.
Single Lithionics 320 Ah with 3 kW
The Lithionics 320 Ah model explicitly allows pairing with inverters up to 3,000 W. While a 3 kW inverter can draw 250–300 A DC at 12 V, the product’s guidance and BMS envelope permit this when installed correctly and operated within spec. Size conductors and protection for worst-case current and minimize sustained 100%-load runtime.
Epoch Essentials 460 Ah with 3 kW
Epoch’s Essential Series BMS is ~200 A continuous / ~400 A (10 s). A 3 kW inverter can demand ~250–300 A DC. Using two Epoch batteries in parallel keeps each unit ≤ ~125–150 A at full load, comfortably under the continuous rating and with better surge headroom.
- DC current @ load ≈ AC Watts ÷ (Battery Volts × Inverter Efficiency).
- Example @ 3,000 W, 12.5 V, 90% → ~267 A. (Xantrex spec sheet shows ≈ 304 A nominal @ 12 V.)
- Rule-of-thumb (12 V): Parallel enough batteries so each stays ≤ its continuous BMS limit at your expected peak draw.
- Cables/protection: Size for worst-case DC current + surge; keep runs short; use symmetric wiring when paralleling to balance current.
- Follow inverter & battery manuals for conductor sizing, fusing/breakers, and required disconnects.
- Configure LiFePO₄ charge profiles (bulk/absorb/float) per manufacturer specs in the inverter/charger.
- Ensure adequate ventilation/clearance around inverter/charger; verify torque on all terminations.
Lithionics LI3 GTX Series
Premium Lithium Power for those needing over engineered performance in off grid situations
Epoch Essentials & Elite Series Lithium
Don’t underestimate this cost-effective, high-performance lithium battery system. It’s rugged, reliable, and loaded with all the right features.
Frequently Asked Questions
Q1: What makes lithium batteries better than AGM or lead-acid for RVs?
Lithium batteries provide more usable energy, faster charging, lighter weight, and longer lifespan. A 100 Ah lithium battery delivers nearly the same usable power as a 170 Ah lead-acid battery.
Q2: How long will a 300 Ah lithium battery last off-grid?
With a 300 Ah (12 V) battery, you have roughly 3,600 Wh of usable energy at 100% depth of discharge — or 3,240 Wh at 90%. Divide your total load watts (e.g., 300 W average) into that figure to estimate runtime — about 10–11 hours in this case.
Q3: Can I charge my RV lithium batteries with solar?
Yes. Solar panels paired with an MPPT controller are ideal for lithium batteries. Make sure your controller supports LiFePO₄ charging profiles.
Q4: What’s the safe discharge limit for lithium RV batteries?
Most quality LiFePO₄ batteries can safely discharge to 90–95%, but for longevity, many users set systems to stop around 80–85%.
Q5: How do I choose between 30A and 50A RV electrical systems?
A 30A system provides a maximum of 3,600 W (120 V × 30 A), while a 50A system provides up to 12,000 W (240 V × 50 A). The calculators above help you match your system to your available power.
Build the Perfect Off-Grid Power System
Our lithium experts can help you design a complete power system — batteries, chargers, solar panels, and inverters — tailored to your RV, van, or tiny home.
Every system is custom-configured for safety, efficiency, and long-term reliability.
About Paogsa Supply Co
Pagosa Supply Co was co-created by passionate RV traveler and YouTube creator Brandon Hensley of Pagosa Adventures, known for real-world testing and education on RV power systems, off-grid travel, and lithium battery technology. After years of RV experience — first in a Leisure Travel Van powered by a Lithionics lithium system, and now in an Airstream Globetrotter equipped with Epoch batteries — our co-founder turned that expertise into a trusted resource for RV owners looking to modernize their energy setup.
At Pagosa Supply Co, we don’t just sell lithium batteries — we live the lifestyle they power. Every product we carry, from Lithionics to Epoch, is field-tested and chosen for safety, performance, and reliability. Our goal is to educate RVers on how lithium technology transforms travel freedom: longer run times, faster charging, and a true off-grid experience.
Whether you’re upgrading your first camper van or building a complete solar power system for your Sprinter or Transit Van, Airstream, Fifth Wheel or Class C RV, Pagosa Supply Co provides expert guidance, proven components, and honest advice backed by real-life experience.