How to Calculate the Right Battery Size for LED Lights (Complete & Practical Guide)

Choosing the right battery size for your LED light is essential—especially for handmade wood or resin lamps. A battery that’s too small will drain quickly, while one that’s too large may be bulky and unnecessary. In this guide, we’ll walk you through how to calculate battery size for LED lights accurately, while considering real-world factors like efficiency, environment, and battery type.

---

🔋 1. Basic Formula to Calculate Battery Capacity

The simplest way to estimate your battery size is by using this formula:

Battery Capacity (Ah) = (LED Power (W) × Runtime (hours)) / Battery Voltage (V)

Example:

• LED Power: 5W

• Runtime: 6 hours

• Battery Voltage: 5V

👉 Result:

(5W×6h)/5V=6Ah(5W × 6h) / 5V = 6Ah(5W×6h)/5V=6Ah

---

⚙️ 2. Adjust for Real-World Conditions

While the basic formula gives you a theoretical value, real-life use requires a few adjustments for reliability and safety:

✅ Safety Factor

Add 30–50% to the calculated capacity to account for battery aging and performance drops.

Example: 6Ah × 1.3 = 7.8Ah (recommended)

✅ Conversion Efficiency Losses

If your lamp uses a voltage regulator or DC-DC converter, expect around 10–15% energy loss. Consider adding 10–20% to your total capacity.

✅ Depth of Discharge (DoD)

Lithium batteries last longer if you avoid full discharge. Ideally, use only 80% of the total capacity.

If you need 6Ah usable, choose a 7.5–8Ah battery.

---

🌡️ 3. How Temperature Affects Battery Performance

• High temperatures reduce battery lifespan.

• Low temperatures temporarily reduce battery efficiency.

👉 If your lamp will be used outdoors or in extreme temperatures, add an extra 10–15% capacity.

---

🔍 4. Choosing the Right Battery Type for LED Wood Lamps

Battery Type	Pros	Cons	Best Use Cases
Lithium-ion (3.7–12V)	Lightweight, rechargeable, long-lasting	Expensive, needs protection circuits	Resin lamps, wood LED lights
AA / AAA batteries	Affordable, easy to find	Low runtime	Holiday lights, small DIY lights
Li-Po batteries	Thin, efficient	Can be sensitive to overcharging	Slim LED crafts, mini lamps
Lead-acid batteries	Cheap, durable	Heavy, bulky	Not ideal for decorative lamps

---

🧮 5. Quick Reference Battery Size Table

LED Power	Usage Time	Required Battery (12V, with 1.3x safety factor)
3W	5 hours	~1.6Ah
5W	6 hours	~3.25Ah
10W	4 hours	~4.3Ah
15W	8 hours	~13Ah

---

💡 Tips for Powering DIY LED Wood Lamps

• Always use a battery with built-in protection or an external BMS (Battery Management System).

• Keep the battery away from heat sources, especially LED chips.

• For products sold to customers, consider using pre-certified lithium cells like protected 18650s.

---

📌 Conclusion

Calculating the right battery size for your LED light isn’t just about math—it’s about planning for long-term performance, safety, and usability. Start with the basic formula, factor in real-life conditions, and select a battery type that fits your design.

Need help picking the right battery for your custom wood LED lamp? The Breakwooden team is here to help—reach out anytime!