Whole House Battery Calculator Hours

Backup Time Formula:

\[ \text{Backup Time (h)} = \frac{\text{Battery Capacity (Ah)} \times \text{Battery Voltage (V)} \times \text{Depth of Discharge} \times \text{Efficiency}}{\text{Load Power (W)}} \]

Battery Capacity:

Battery Voltage:

Depth of Discharge:

(0-1)

Efficiency:

(0-1)

Load Power:

Backup Time:

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1. What is the Backup Time Calculation?

The backup time calculation estimates how long a battery system can power your home during an outage. It considers battery capacity, voltage, how much of the battery can be used (depth of discharge), system efficiency, and your home's power consumption.

2. How Does the Calculator Work?

The calculator uses the backup time formula:

\[ \text{Backup Time (h)} = \frac{\text{Battery Capacity (Ah)} \times \text{Battery Voltage (V)} \times \text{Depth of Discharge} \times \text{Efficiency}}{\text{Load Power (W)}} \]

Where:

Battery Capacity — Total energy storage in amp-hours (Ah)
Battery Voltage — System voltage (typically 12V, 24V, or 48V)
Depth of Discharge — Fraction of battery that can be used (e.g., 0.8 for 80%)
Efficiency — System efficiency including inverter losses (typically 0.85-0.95)
Load Power — Your home's average power consumption in watts

Explanation: The formula converts battery capacity to watt-hours, applies usage limits and efficiency factors, then divides by power consumption to get runtime.

3. Importance of Backup Time Calculation

Details: Knowing your backup time helps size battery systems appropriately, plan for outages, and understand your energy independence during emergencies.

4. Using the Calculator

Tips: For accurate results, measure your actual power consumption rather than estimating. Depth of discharge depends on battery type (lithium batteries typically allow 80-90% DoD, while lead-acid is often limited to 50%).

5. Frequently Asked Questions (FAQ)

Q1: What's a typical depth of discharge for lithium batteries?
A: Most lithium batteries allow 80-90% DoD, while lead-acid is typically limited to 50% for longevity.

Q2: How do I measure my home's power consumption?
A: Use an energy monitor or check your utility bill for average daily usage, then divide by 24 for approximate hourly usage.

Q3: What affects system efficiency?
A: Inverter efficiency (90-95% for good models), wiring losses, and battery charge/discharge efficiency.

Q4: Should I size for peak or average load?
A: Size batteries for average load (this calculator), but ensure your inverter can handle peak loads.

Q5: How does temperature affect backup time?
A: Cold temperatures reduce battery capacity (especially lead-acid), potentially decreasing backup time by 20-50% in freezing conditions.