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RV Battery Bank Calculator — Ah Sizing & Wiring Config

Size your RV battery bank with chemistry comparison, wiring configuration, and cost estimates

Battery Bank Required

313 Ah

Capacity

3.8 kWh

Batteries

2

Weight

104 lbs

Wh
days

Battery Bank Required

313 Ah

3.8 kWh at 12V

Batteries Needed

2 × 200Ah

Total Capacity

4.8 kWh

Est. Weight

104 lbs

Est. Cost

$1,800

Wiring Configuration

Series (for voltage)1 in series
Parallel (for capacity)2 in parallel
Total batteries2
Cycle life (Lithium (LiFePO4))3,000 cycles

Depth of Discharge

Lithium (LiFePO4) batteries should not be discharged below 20% state of charge. The required Ah already accounts for 80% DOD.

What You'll Need

CRAFTSMAN 1500A Lithium Jump Starter Power Pack

CRAFTSMAN 1500A Lithium Jump Starter Power Pack

$80-$1204.4
View on Amazon
NOCO GENIUS1 Smart Battery Charger/Maintainer

NOCO GENIUS1 Smart Battery Charger/Maintainer

$25-$354.7
View on Amazon
708Pcs Waterproof Electrical Connectors Kit

708Pcs Waterproof Electrical Connectors Kit

$25-$354.4
View on Amazon
Lectron Level 2 EV Charger 240V 32A

Lectron Level 2 EV Charger 240V 32A

$180-$2504.5
View on Amazon
BougeRV EV Charger Holster J1772 Wall Mount

BougeRV EV Charger Holster J1772 Wall Mount

$12-$184.5
View on Amazon
CRAFTSMAN 1500A Lithium Jump Starter Power Pack

CRAFTSMAN 1500A Lithium Jump Starter Power Pack

$80-$1204.4
View on Amazon
NOCO GENIUS1 Smart Battery Charger/Maintainer

NOCO GENIUS1 Smart Battery Charger/Maintainer

$25-$354.7
View on Amazon
708Pcs Waterproof Electrical Connectors Kit

708Pcs Waterproof Electrical Connectors Kit

$25-$354.4
View on Amazon
Lectron Level 2 EV Charger 240V 32A

Lectron Level 2 EV Charger 240V 32A

$180-$2504.5
View on Amazon
BougeRV EV Charger Holster J1772 Wall Mount

BougeRV EV Charger Holster J1772 Wall Mount

$12-$184.5
View on Amazon

As an Amazon Associate, we earn from qualifying purchases.

Frequently Asked Questions

Q

How many amp-hours does my RV battery bank need?

Divide your daily watt-hour consumption by your system voltage and battery depth of discharge. For 1,500 Wh daily on a 12V lithium system: 1,500 / (12 × 0.8) = 156 Ah minimum. Add autonomy days to handle cloudy weather without recharging.

  • Formula: Ah = (Daily Wh × Days of Autonomy) / (System Voltage × DOD)
  • 1,500 Wh/day, 2 days autonomy, 12V lithium: (1,500 × 2) / (12 × 0.8) = 313 Ah
  • Same setup with AGM: (1,500 × 2) / (12 × 0.5) = 500 Ah (60% more capacity needed)
  • Most moderate RV setups need 200–400 Ah of lithium at 12V
  • Full-time RVers with AC may need 600+ Ah at 24V or 48V
Daily Use1-Day Autonomy (LiFePO4)2-Day Autonomy (LiFePO4)2-Day Autonomy (AGM)
800 Wh84 Ah167 Ah267 Ah
1,500 Wh156 Ah313 Ah500 Ah
3,000 Wh313 Ah625 Ah1,000 Ah
Q

What is depth of discharge and why does it matter?

Depth of discharge (DOD) is the percentage of battery capacity you can safely use before recharging. Lithium batteries handle 80% DOD, meaning you can use 80% of their rated capacity. Lead-acid and AGM batteries should only be discharged to 50% DOD to preserve cycle life.

  • Lithium (LiFePO4): 80% DOD = 160 Ah usable from a 200 Ah battery
  • AGM: 50% DOD = 100 Ah usable from a 200 Ah battery
  • Flooded lead-acid: 50% DOD = 100 Ah usable from a 200 Ah battery
  • Exceeding recommended DOD dramatically shortens battery life
  • Lithium maintains voltage better at deep discharge (12.8V vs 11.8V for lead-acid at 50% DOD)
Q

Should I wire RV batteries in series or parallel?

Series wiring increases voltage while keeping amp-hours the same. Parallel wiring increases amp-hours while keeping voltage the same. Most RV systems use a combination: series strings to reach system voltage, then parallel strings for capacity. A 24V system uses two 12V batteries in series; adding capacity means another series pair in parallel.

  • Series: 2 × 12V 200Ah batteries = 24V 200Ah (doubles voltage, same Ah)
  • Parallel: 2 × 12V 200Ah batteries = 12V 400Ah (same voltage, doubles Ah)
  • 24V system with 400Ah: 4 batteries total (2 series × 2 parallel)
  • 48V system with 200Ah: 4 batteries in series (4 × 12V)
  • Always use identical batteries (same brand, age, capacity) in any configuration
ConfigurationResult VoltageResult AhUse Case
2S (Series)24V200 AhHigher voltage system
2P (Parallel)12V400 AhMore capacity at 12V
2S2P24V400 AhHigh capacity + higher voltage
4S48V200 AhLarge system, lower current
Q

How much does an RV battery bank weigh?

Battery weight varies dramatically by chemistry. A 200Ah lithium bank weighs about 52 lbs, while the same usable capacity in AGM (400Ah at 50% DOD) weighs 240 lbs. For weight-sensitive RV builds like vans, lithium saves 150–300 lbs compared to lead-acid equivalents.

  • Lithium (LiFePO4): ~0.26 lbs per Ah = 52 lbs for 200 Ah
  • AGM: ~0.60 lbs per Ah = 120 lbs for 200 Ah (but only 100 Ah usable)
  • Flooded lead-acid: ~0.58 lbs per Ah = 116 lbs for 200 Ah (100 Ah usable)
  • For 200 Ah usable: lithium = 65 lbs, AGM = 240 lbs (3.7x heavier)
  • Weight savings directly translate to better fuel economy and cargo capacity
Q

How long do RV batteries last?

Lithium (LiFePO4) batteries last 3,000+ full cycles (8–10 years of daily use), AGM lasts about 600 cycles (2–3 years daily), and flooded lead-acid about 400 cycles (1–2 years daily). Cycle life assumes proper charging and staying within recommended DOD limits.

  • Lithium: 3,000+ cycles at 80% DOD = 8–10 years of daily cycling
  • AGM: ~600 cycles at 50% DOD = 2–3 years of daily cycling
  • Gel: ~800 cycles at 50% DOD = 2–3 years of daily cycling
  • Flooded lead-acid: ~400 cycles at 50% DOD = 1–2 years of daily cycling
  • Partial cycling (30–40% DOD instead of full DOD) can double effective cycle life

Example Calculations

1Moderate RVer with Lithium (12V)

Inputs

Daily Consumption1,500 Wh
Days of Autonomy2
Battery ChemistryLithium (LiFePO4)
System Voltage12V
Battery Size200 Ah each

Result

Battery Bank Required313 Ah
Batteries Needed2 × 200 Ah
Total Capacity4.8 kWh
Estimated Weight104 lbs
Estimated Cost$1,800

(1,500 × 2) / (12 × 0.8) = 313 Ah required. Ceil to 2 × 200 Ah = 400 Ah (2 parallel). 1 series (12V system). Total: 2 batteries. Weight: 2 × 200 × 0.26 = 104 lbs. Cost: 2 × 200 × $4.50 = $1,800.

2Budget Setup with AGM (12V)

Inputs

Daily Consumption1,000 Wh
Days of Autonomy1
Battery ChemistryAGM (Sealed)
System Voltage12V
Battery Size100 Ah each

Result

Battery Bank Required167 Ah
Batteries Needed2 × 100 Ah
Total Capacity2.4 kWh
Estimated Weight120 lbs
Estimated Cost$400

(1,000 × 1) / (12 × 0.5) = 167 Ah required. Ceil to 2 × 100 Ah = 200 Ah. 1 series (12V). Total: 2 batteries. Weight: 2 × 100 × 0.6 = 120 lbs. Cost: 2 × 100 × $2.00 = $400.

3Full-Timer with 24V Lithium System

Inputs

Daily Consumption3,000 Wh
Days of Autonomy2
Battery ChemistryLithium (LiFePO4)
System Voltage24V
Battery Size200 Ah each

Result

Battery Bank Required313 Ah
Batteries Needed4 × 200 Ah
Total Capacity9.6 kWh
Estimated Weight208 lbs
Estimated Cost$3,600

(3,000 × 2) / (24 × 0.8) = 313 Ah required. Ceil to 2 parallel × 200 Ah = 400 Ah. 2 series for 24V. Total: 4 batteries. Weight: 4 × 200 × 0.26 = 208 lbs. Cost: 4 × 200 × $4.50 = $3,600.

Formulas Used

Required Battery Capacity

Ah = (Daily Wh × Days of Autonomy) / (System Voltage × DOD)

Calculates the minimum battery bank capacity in amp-hours based on energy needs, reserve days, and safe discharge depth for the chosen chemistry.

Where:

Daily Wh= Total daily energy consumption in watt-hours
Days of Autonomy= Number of days without any recharging source
System Voltage= Battery bank voltage: 12V, 24V, or 48V
DOD= Depth of discharge: 0.8 for lithium, 0.5 for AGM/lead-acid

Series/Parallel Battery Count

Total Batteries = Series Count × Parallel Count

Determines how many physical batteries are needed. Series strings build voltage; parallel strings build capacity.

Where:

Series Count= System voltage / individual battery voltage (e.g., 24V / 12V = 2)
Parallel Count= Required Ah / individual battery Ah, rounded up

Energy Capacity in kWh

kWh = (Total Ah × System Voltage) / 1,000

Converts the battery bank capacity from amp-hours to kilowatt-hours for easier comparison with energy consumption.

Where:

Total Ah= Total amp-hour capacity of the battery bank
System Voltage= Battery bank nominal voltage (12V, 24V, or 48V)

RV Battery Bank Sizing and Chemistry Guide

Your RV battery bank is the heart of your off-grid electrical system. It stores energy from solar panels, shore power, or alternator charging for use when you need it. Getting the sizing right means the difference between a comfortable boondocking experience and constantly running out of power or hauling unnecessary weight.

The sizing formula is straightforward: multiply your daily energy consumption (Wh) by the number of days you want to go without recharging, then divide by your system voltage and the battery’s safe depth of discharge. For a 1,500 Wh/day setup with 2 days of autonomy on a 12V lithium system, that’s (1,500 × 2) / (12 × 0.8) = 313 Ah. The same scenario with AGM batteries requires 500 Ah because of the lower 50% DOD limit.

Battery chemistry choice has massive implications beyond capacity. Lithium (LiFePO4) batteries cost 2–3x more upfront but deliver 80% usable capacity, last 5x longer (3,000 vs 600 cycles), and weigh 60% less than AGM equivalents. When you factor in replacement costs over a 10-year period, lithium is actually cheaper per cycle: about $0.38 per cycle vs $1.33 for AGM.

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Last Updated: Mar 25, 2026

This calculator is provided for informational and educational purposes only. Results are estimates and should not be considered professional financial, medical, legal, or other advice. Always consult a qualified professional before making important decisions. UseCalcPro is not responsible for any actions taken based on calculator results.

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