What size battery should I use for my RV?
Choosing the right RV battery depends on your power needs, usage patterns, and space constraints. For most RVs, a 12V lithium iron phosphate (LiFePO4) battery with 100–300Ah capacity provides optimal balance between weight, cycle life (3,000+ cycles), and energy density. Group 24/31 sizes fit standard compartments, while built-in battery management systems (BMS) prevent overcharging. For solar-dependent setups, prioritize LiFePO4 over AGM due to faster recharge acceptance (up to 1C).
Best Lithium Battery Options for RVs
How to calculate RV battery capacity needs?
Estimate daily watt-hour consumption by multiplying appliance wattages by usage hours. A 100Ah LiFePO4 battery (1,280Wh usable) typically powers lights (10W x 5h = 50Wh), fridge (150W x 8h = 1,200Wh), and charging for 1–2 days. Pro Tip: Add 20% buffer for unexpected loads.
Start by listing all DC appliances and their runtime. For example, a 12V RV with a 10W LED light (5 hours), 150W compressor fridge (8 hours), and 50W TV (3 hours) consumes (10×5)+(150×8)+(50×3)=1,400Wh daily. At 12V, that requires 1,400Wh ÷ 12V = ~117Ah/day. Lithium batteries safely discharge to 90% DoD, so a 130Ah LiFePO4 battery meets single-day needs. Transitional tip: Multiply by “no sun” days—if needing 3 days autonomy, opt for 390Ah. Real-world example: Boondockers often use 400Ah lithium banks paired with 400W solar for sustainable off-grid power.
LiFePO4 vs AGM: Which suits RVs better?
LiFePO4 outperforms AGM in weight (70% lighter), lifespan (10x cycles), and charge speed. A 100Ah LiFePO4 weighs 26 lbs vs. AGM’s 60 lbs, crucial for RV payload limits. However, AGM costs 40% less upfront for budget-conscious users.
While AGM batteries dominated RVs for decades, lithium technology now offers compelling advantages. Mechanically, LiFePO4 cells tolerate deeper discharges (90% vs AGM’s 50% DoD), effectively doubling usable capacity. A 100Ah LiFePO4 delivers 1280Wh (12.8V x 100Ah x 100% DoD) versus AGM’s 600Wh (12V x 100Ah x 50% DoD). Thermally, lithium handles -20°C to 60°C charging ranges versus AGM’s narrower 0–40°C. However, lithium requires specialized chargers—mismatched AGM chargers risk cell damage. For example, a 30A converter takes 5 hours to charge 100Ah LiFePO4 (30A x 14.6V = 438W) versus 10+ hours for AGM. Pro Tip: Install a battery monitor to track state-of-charge accurately.
| Feature | LiFePO4 | AGM |
|---|---|---|
| Cycle Life | 3,000–5,000 | 400–600 |
| Weight (100Ah) | 26 lbs | 60–70 lbs |
| Charge Temp | -20°C–60°C | 0°C–40°C |
What physical size fits RV battery compartments?
Group 24 (10.25″L x 6.8″W) and Group 31 (13″L x 6.8″W) are RV standards. Lithium’s compact design allows higher Ah in same size—Battle Born 100Ah fits Group 24, while AGM equivalents need Group 31 for 100Ah.
RV battery compartments typically follow BCI group sizing. Group 24 (L10.25″ x W6.8″ x H8.9″) suits smaller RVs with ≤100Ah needs, while Group 31 (L13″ x W6.8″ x H9.4″) accommodates 200Ah+ banks. Lithium’s modular design enables creative layouts—six 50Ah modules can fill irregular spaces. For slide-in truck campers, consider GC2 golf cart batteries (10.3″ x 7.1″ x 10.9″) wired in series for 12V. Critical warning: Verify terminal positions—some lithium batteries reverse polarity vs AGM. A real-world example: Airstream’s 2025 Interstate uses two Group 31 LiFePO4 batteries (200Ah total) in factory compartments originally designed for AGM.
How does solar integration affect battery choice?
Solar demands high charge acceptance. LiFePO4 absorbs 100A (1C rate) vs AGM’s 20A max, enabling faster solar replenishment. A 400W solar array can fully charge 200Ah LiFePO4 in 4 sun hours vs 10+ for AGM.
When pairing solar with RV batteries, lithium’s efficiency shines. Their flat voltage curve allows maximum power point tracking (MPPT) controllers to operate at 95–97% efficiency versus AGM’s 85%. For a 400W solar system, that’s 380W usable vs 340W with AGM. Transitional note: Lithium’s 100% depth of discharge means you can safely drain batteries overnight, then fully recharge by noon. Real-world example: A 300Ah LiFePO4 bank with 600W solar provides indefinite off-grid power for LED lights (20W), fridge (150W), and laptop (50W). Pro Tip: Oversize solar by 30% to account for cloudy days and panel degradation.
| Parameter | LiFePO4 + Solar | AGM + Solar |
|---|---|---|
| Recharge Time (200Ah) | 3–4 hours | 8–10 hours |
| Winter Performance | Heating required <0°C | Reduced capacity |
Fasta Power Expert Insight
FAQs
Yes, if your RV’s converter supports LiFePO4 charging profiles (14.2–14.6V absorption). Older PWM controllers may need upgrading to lithium-compatible MPPT units.
How many lithium batteries can I parallel?
Up to 4 identical batteries with <1mV terminal voltage difference. Use bus bars instead of daisy-chaining to minimize imbalance.
Do lithium RV batteries need venting?
No—LiFePO4 is sealed and non-toxic. Unlike AGM, they can be safely mounted inside living areas.