Battery Sizing Chart Guide
Choosing the right battery size starts with understanding your load profile. This reference chart maps common applications and energy consumption ranges to recommended battery capacities, helping you quickly identify where your system falls without running a full calculation.
How to Use This Chart
Identify your application type in the chart below. The daily load column gives you a rough energy consumption range for that application. The recommended battery capacity columns show what you need at 12V, 24V, and 48V system voltages. These are starting-point estimates — use the Battery Sizing Calculator for precise sizing with your actual numbers.
All capacity values assume 80% DoD for LFP lithium and 50% DoD for lead-acid. The usable capacity is what matters — the installed capacity must be larger to respect these discharge limits.
Master Sizing Chart
| Application | Daily Load | 12V Ah | 24V Ah | 48V Ah |
|---|---|---|---|---|
| Phone / tablet charging only | 30–60 Wh | 5–10 | — | — |
| Laptop + lights + router | 200–500 Wh | 50–100 | 25–50 | — |
| Small cabin (lights, fridge, fan) | 1–3 kWh | 200–500 | 100–250 | 50–125 |
| RV / camper (12V appliances) | 1–4 kWh | 200–600 | 100–300 | — |
| Essential home loads (overnight) | 3–8 kWh | 600–1,500 | 300–750 | 150–375 |
| Full home (moderate usage) | 8–20 kWh | Not practical | 1,000–2,500 | 400–1,000 |
| Large home / EV charging | 20–60 kWh | Not practical | Not practical | 1,000–3,000 |
| Small business / office | 15–50 kWh | Not practical | 2,000–5,000 | 800–2,500 |
| Telecom / cell tower | 5–30 kWh | Not practical | 1,000–3,000 | 500–1,500 |
Values are approximate ranges for 1–2 days of autonomy at typical DoD limits. Use the Battery Sizing Calculator for precise values with your specific parameters.
Load Profile Categories
Load profiles group common usage patterns into three broad categories. Understanding which category your application falls into helps narrow down the capacity range before you run exact numbers.
Light Load (300–2,000 Wh/day)
Phone charging, LED lighting, laptop, small fan, Wi-Fi router. Typical for tents, basic cabins, and emergency lighting. A single 12V 100Ah battery covers most light-load scenarios.
Medium Load (2–10 kWh/day)
Refrigerator, well pump, washer, TV, lights, small appliances. Typical for off-grid cabins, RVs, and essential home backup. A 24V 200Ah or 48V 100Ah bank is the starting point.
Heavy Load (10–60 kWh/day)
Full home with HVAC, electric range, dryer, EV charging. Typical for whole-home backup and commercial installations. Requires 48V systems with 400+ Ah capacity.
Voltage Selection Guide
System voltage affects cable size, inverter availability, and practical Ah requirements. Higher voltages reduce current for the same power, allowing thinner cables and lower conduction losses.
| Voltage | Max Practical Power | Best For | Cable Gauge |
|---|---|---|---|
| 12V | ~1.5 kW | Portable, RV, marine, small systems | 4–6 AWG for short runs |
| 24V | ~5 kW | Medium off-grid, small homes | 6–8 AWG for typical runs |
| 48V | ~15 kW | Homes, commercial, telecom | 8–10 AWG for typical runs |
| 400V | 100+ kW | Utility-scale BESS | High-voltage industrial cable |
Worked Example: Choosing from the Chart
Scenario: A small off-grid cabin with the following loads:
- LED lighting: 40W × 5h = 200 Wh
- Mini fridge: 80W × 12h (50% duty) = 480 Wh
- Laptop: 65W × 3h = 195 Wh
- Wi-Fi router: 10W × 24h = 240 Wh
- Phone charging: 15W × 2h = 30 Wh
Total daily load:
From the chart: This falls in the "Small cabin (lights, fridge, fan)" row at 1–3 kWh/day. The chart recommends 200–500 Ah at 12V, or 100–250 Ah at 24V.
Selection: A 24V 150Ah LFP bank (3.6 kWh) provides about 3 days of autonomy at this load, with 80% DoD giving 2.88 kWh usable. This is a practical, cost-effective choice for a cabin with reliable solar charging.
Try It
Use the Battery Sizing Calculator for a precise recommendation based on your exact loads.
Open Battery Sizing CalculatorHome Backup
Sizing for home backup? Use the Home Backup Calculator with critical load prioritization.
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Overview of the sizing process, why it matters, and key design considerations.
Read Guide →Home Battery Sizing Guide
Step-by-step guide to sizing a residential battery backup system for essential loads.
Read Guide →Frequently Asked Questions
How do I read the battery sizing chart?
Find your application or load profile in the left column. The corresponding row shows the recommended Ah rating range at your system voltage. For example, if you are powering a small cabin with lights, a fridge, and a laptop, the chart might suggest 200–400 Ah at 12V or 100–200 Ah at 24V.
What Ah rating do I need for home backup?
For a typical home with essential loads (refrigerator, lights, router, medical devices) at 2–5 kWh/day, a 48V 200–400 Ah LFP bank (10–20 kWh) provides 1–2 days of autonomy. Larger homes with 10+ kWh/day consumption may need 400–800 Ah at 48V.
Can I use the chart for any battery chemistry?
The chart shows capacity ranges based on energy requirements, not chemistry. However, usable capacity varies by chemistry. A 200 Ah lead-acid bank at 50% DoD provides only 100 Ah usable, while the same LFP bank at 80% DoD provides 160 Ah usable. The chart accounts for typical DoD limits per chemistry.
What if my application falls between two chart entries?
Round up to the larger size. It is always better to have 20% excess capacity than to fall short. The cost of undersizing — system shutdown, load shedding, or premature battery replacement — far outweighs the marginal cost of additional capacity.