Tech-dat/power-dat/battery-dat/battery-capacity-dat/battery-capacity-dat.md
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+# battery-capacity-dat
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+## Car Sedan Lead-Acid battery
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+- [[lead-acid-battery-dat]]
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+- Typical Voltage (V): 12 V
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+- Typical Capacity Range (Ah): 40 Ah to 70 Ah
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+Calculating Energy (Wh) = Voltage (V) × Capacity (Ah)
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+- Minimum Energy: 12 V × 40 Ah = 480 Wh
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+- Maximum Energy: 12 V × 70 Ah = 840 Wh
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+So, the energy stored in a typical car lead-acid battery is usually between 480 Wh and 840 Wh.
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+
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+## 20000 mAh * 3.7V
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+Energy (Wh) = 20 Ah × 3.7 V = 74 Wh
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+## 2.6Ah * 12V
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+Energy (Wh) = 2.6 Ah × 12 V = 31.2 Wh
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+
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+## 1000 Wh
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+1000 watt-hours (Wh) == 1 度
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+Runtime = 1000 Wh / 5V * 1A = 1000 Wh / 5W = 200 hours
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+## quick calculation
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+2000 mAh = 2 Ah
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+Runtime ≈ (2 Ah * 3.7 V * 0.85) / (1 A * 5 V) ≈ 1.26 hours
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+for 20000 mAh, == 12.6 hours
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+## Calculating Runtime for a 2000mAh Power Bank Supplying a 1A @ 5V Device
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+Here's a breakdown of how to estimate the runtime:
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+### 1. Power Bank Energy
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+* **Capacity:** 2000 mAh (milliampere-hours) = 2 Ah (ampere-hours)
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+* **Nominal Voltage:** 3.7 V (typical for lithium-ion/polymer batteries)
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+* **Total Energy (Watt-hours, Wh):** Capacity (Ah) × Voltage (V)
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+ * `2 Ah * 3.7 V = 7.4 Wh`
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+### 2. Device Power Consumption
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+* **Current:** 1 A (ampere)
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+* **Voltage:** 5 V (standard USB output)
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+* **Power Needed (Watts, W):** Current (A) × Voltage (V)
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+ * `1 A * 5 V = 5 W`
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+
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+### 3. Efficiency Consideration
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+Power banks are not 100% efficient when converting their internal battery voltage (3.7V) to the required 5V output. Energy is lost, primarily as heat, during this conversion.
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+* **Estimated Efficiency:** Let's assume an average efficiency of **85%** (or 0.85). This can vary between 80% and 95% depending on the quality of the power bank circuitry.
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+
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+### 4. Effective Energy Available
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+This is the amount of the power bank's stored energy that can actually be delivered to the device after accounting for conversion losses.
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+* **Effective Energy:** Total Energy (Wh) × Efficiency
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+ * `7.4 Wh * 0.85 ≈ 6.29 Wh`
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+
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+### 5. Calculate Runtime
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+* **Runtime (hours):** Effective Energy Available (Wh) / Device Power Consumption (W)
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+ * `6.29 Wh / 5 W ≈ 1.26 hours`
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+
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+### Conclusion
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+A 2000mAh, 3.7V power bank can theoretically supply a device drawing 1A at 5V for approximately **1.26 hours**, or about **1 hour and 15 minutes**.
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+**Disclaimer:** This is an estimate. Actual runtime depends on factors such as:
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+* The precise efficiency of the specific power bank.
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+* The age and health of the battery cells.
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+* The quality of the charging cable (resistance losses).
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+* Ambient temperature.
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+* Whether the device's power draw is constant or fluctuates.
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+## ref
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+- [[Lead-acid-battery-dat]]
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Tech-dat/tech-dat.md
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- [[RF-DAT]]
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-- [[LTE.-datmd]] - [[POE-dat]] - [[low-power-test-dat]] - [[M2M-interface]]
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+- [[LTE-dat]] - [[POE-dat]] - [[low-power-test-dat]] - [[M2M-interface]]
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- [[bluetooth-dat]]
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### Power
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-- [[power-dat]]
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+- [[power-dat]] - [[battery-dat]]
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### Interactive
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