battery

+

+

+

+- [[fab-dat]] - [[fab-tools-dat]] - [[battery-tools-dat]]

+

+

+## 18650 battery capacity test

+

+### Method 1: Using a Dedicated Electronic Load Tester (Most Accurate & Recommended)

+

+This is the most precise method used by enthusiasts and professionals. It allows you to set exact parameters and often exports data to a PC to plot a discharge curve. Popular budget-friendly units include the **electrodragon** or generic digital constant-current electronic load modules.

+

+#### 1. Hardware Required

+* **Electronic Load Tester** (supporting Constant Current / CC mode).

+

+* `四线制电池夹`（Kelvin夹） == **4-Wire Battery Test Fixture (Kelvin Clamp):** **Crucial!** Standard 2-wire holders introduce voltage drops due to lead and contact resistance, causing premature cut-off readings. A 4-wire fixture uses two wires for the heavy discharge current and two separate wires exclusively to measure voltage at the battery terminals accurately. - [[Kelvin-Clamp-dat]]

+

+

+* **PC Connection Cable** (optional, for software graphing).

+

+#### 2. Step-by-Step Procedure

+1. **Fully Charge:** Charge the 18650 cell to exactly **4.2V** using a standard lithium-ion charger. Let it rest for 10–20 minutes so the chemistry stabilizes and the resting voltage settles.

+2. **Connect:** Place the cell into the 4-wire fixture, ensuring strict adherence to positive (+) and negative (-) polarities, and connect it to the electronic load.

+3. **Configure Parameters:**

+ * **Discharge Mode:** Set to **CC** (Constant Current).

+ * **Discharge Current:** Base this on your cell type. For standard capacity cells, a rate of **0.2C to 0.5C** is ideal (e.g., for a 3000mAh battery, 0.5C is 1.5A). For high-drain power cells, you can test at 1A, 2A, or higher. *Note: Higher currents generate more internal heat, which slightly lowers the measured capacity.*

+ * **Cut-off Voltage:** Set between **2.5V and 2.75V** (check your specific cell's datasheet). Never set it below 2.0V, as over-discharging will permanently damage the battery.

+4. **Run the Test:** Start the discharge. The electronic load will dynamically adjust its resistance to keep the current perfectly constant while tracking the elapsed time and accumulating capacity (`mAh` or `Ah`).

+5. **Completion:** Once the cell voltage drops to your configured cut-off limit, the tester automatically disconnects the load and alerts you. The finalized `mAh` reading on the screen is your true battery capacity.

+

+

+## 18650 battery capacity

+

+The capacity of an **18650 lithium-ion battery** depends heavily on its **brand**, **intended application (Capacity-type vs. High-drain/Power-type)**, and whether it is a genuine product.

+

+For authentic, reputable brands, the standard capacity range is typically between **1,200mAh and 3,500mAh**.

+

+Here is a detailed breakdown of 18650 battery capacities:

+

+### 1. Standard Capacity Ranges by Type

+* **Capacity-Type / Regular Batteries (Low Discharge Current):** Typically range from **2,600mAh to 3,500mAh**. These are designed for devices that require long runtime but low current draw, such as high-powered flashlights, power banks, and laptop battery packs.

+* **High-Drain / Power-Type Batteries (High Discharge Current):** Typically range from **1,500mAh to 2,500mAh**. To safely output massive currents (e.g., 10A, 20A, or up to 30A) for power tools, vacuum cleaners, and e-bikes, these batteries sacrifice overall energy density/capacity.

+

+---

+

+### 2. The Physical and Technical Limits

+As of current chemical engineering limits, the maximum physical capacity for a genuine, tier-1 manufactured 18650 battery is around **3,500mAh to 3,600mAh** (such as the famous *Panasonic NCR18650GA* or *Samsung 35E*).

+

+> ⚠️ **Beware of Fakes and Counterfeits:** If you see 18650 batteries online claiming capacities like **4,000mAh, 5,000mAh, or 9,900mAh**, they are **100% fake**. These are usually produced by counterfeit workshops that wrap recycled, low-quality cells in misleading labels. Given the fixed physical dimensions of an 18650 cell (18mm diameter, 65mm length), it is scientifically impossible to fit that much capacity using current lithium-ion technology.

+

+---

+

+### 3. Popular Models from Top-Tier Manufacturers

+

+| Brand | Model | Nominal Capacity | Battery Type | Common Applications |

+| :-------------------- | :----------- | :--------------- | :---------------------------- | :------------------------------------ |

+| **Panasonic / Sanyo** | NCR18650B | **3400mAh** | Capacity-Type | Flashlights, laptops, energy storage |

+| **Panasonic / Sanyo** | NCR18650GA | **3500mAh** | Capacity-Type (High-capacity) | Premium flashlights, electric bikes |

+| **Samsung** | INR18650-35E | **3500mAh** | Capacity-Type | Power banks, long-runtime electronics |

+| **Samsung** | INR18650-25R | **2500mAh** | High-Drain (20A) | Power tools, cordless vacuums |

+| **Murata / Sony** | US18650VTC6 | **3000mAh** | High-Drain (30A) | High-performance tools, drones |

+| **LG** | INR18650-HG2 | **3000mAh** | High-Drain (20A) | High-power appliances ("LG Choc") |

+

+---

+

+### 4. Factors Affecting Real-World Usable Capacity

+The capacity labeled on the battery isn't always the exact amount of energy you will get in real-world usage:

+* **Discharge Cut-off Voltage:** A typical 18650 has a nominal voltage of 3.6V/3.7V and a full charge of 4.2V. If your device automatically shuts off when the battery drops to 3.0V, you won't be able to access the remaining energy stored down to the absolute safe limit (usually 2.5V).

+* **Discharge Current Draw:** Drawing a massive current from a standard capacity-type cell will cause high internal resistance and heat. This causes the voltage to drop prematurely, significantly reducing the actual capacity delivered.

+* **Operating Temperature:** Lithium-ion performance drops drastically in cold environments. In sub-zero temperatures (below 0°C/32°F), internal chemical activity slows down, causing a temporary but significant reduction in usable capacity.

+

+

+

+

+

+

+# Kelvin-Clamp-dat

+

+- [[18650-dat]] - [[21700-dat]] - [[battery-li-size-dat]] - [[26650-dat]]

+

+**Crucial!** Standard 2-wire holders introduce voltage drops due to lead and contact resistance, causing premature cut-off readings.

+

+A 4-wire fixture uses two wires for the heavy discharge current and two separate wires exclusively to measure voltage at the battery terminals accurately.

+

+

+

+

+

+

+

+

+

+

+- 16MM - 4芯 - 插头 探针

+- 16MM - 4芯 - 插头 开尔文夹

+- 12MM - 4芯 - 插头 探针

+- 12MM - 4芯 - 插头 开尔文夹

+

+

+

+

+

+## ref

+

+

+

+

+# battery-capacity-tester-dat

+

+- [[battery-dat]] - [[battery-tester-dat]] - [[battery-tools-dat]] - capacity - [[electronic-loader-dat]]

+

+- [[kelvin-clamp-dat]]

+

+

+

+## test methods

+

+

+

+

+二 == 当你在测试或者老化DC电源类产品时，可以用如下图第一种的精简2线制接线方法 A+ V+ 短接，A- V- 短接。

+

+四 == 当你需要精密测试电池容量时，可按下图第二种的4线制接线方法，这样电压测量不受电流导线压降的影响，使得电压测量更精准，并能准确判断电池电压准确停止放电而准确保护电池和容量的准确测试

+

+

+

+## ref

+

+# battery-tester-dat

+

+- [[battery-dat]] - [[battery-tester-dat]] - [[battery-tools-dat]]

+

+## testing tools

+

+

+- [[battery-tools-dat]]

+

+- capacity - [[electronic-loader-dat]]

+- internal resistance == discharge current - [[internal-resistance-meter-dat]]

+

+

+

+

+## Q: Can I determine a lead‑acid battery's capacity by measuring its voltage with a multimeter for a fixed short time (e.g., 5 minutes)?

+

+A: No. A 5‑minute voltage reading cannot reliably determine battery capacity.

+

+Why:

+- **Battery voltage is not a direct, linear indicator of remaining capacity**; voltage changes little across much of the discharge curve.

+

+- Capacity is defined by total charge delivered: Capacity (Ah) = Current (A) × Time (h). You must discharge with a known constant current to a cutoff voltage to measure capacity.

+

+- A multimeter alone cannot integrate current over time (coulomb counting).

+

+- Short tests can only give rough hints; extrapolating capacity from a 5‑minute test (even at high current) yields large errors.

+

+Quick practical checks for battery health:

+

+- Resting (open‑circuit) voltage: charge fully, wait ~12 hours, then measure. ≳12.6 V indicates generally healthy for a 12 V lead‑acid battery.

+- Internal resistance test: fast and useful indicator of capacity degradation.

+- Short high‑current load test (starter test): observe voltage sag under load.

+

+### To measure capacity accurately:

+

+- Use a constant‑current electronic load or a dedicated battery capacity tester and discharge to a defined cutoff (e.g., 10.5 V for 12 V batteries); record current × time.

+- Or use a device that logs current over time (coulomb counter) while discharging.

+

+### Q: How does a lead‑acid battery's internal resistance typically change after ~200 charge/discharge cycles?

+

+A: Internal resistance generally increases after repeated cycling, but the magnitude depends on usage conditions.

+

+Why:

+

+- Repeated charge/discharge causes sulfation (lead sulfate crystallization 硫化), active‑material shedding, separator aging, and electrolyte stratification — all of which reduce ionic/electronic pathways and raise internal resistance.

+

+Typical trend (example: small 12 V sealed lead‑acid):

+- Factory/new: ~7–9 mΩ (milliohms)

+- After ~200 cycles at deep discharge (≈80% DOD): can rise to ~12–18 mΩ

+

+Notes on variation:

+

+- Shallow cycling (≈30% DOD) and moderate temperature: resistance may only increase modestly (e.g., 20–30%).

+- Deep cycling combined with high temperature: resistance can increase much more, potentially doubling.

+

+Practical scenarios (examples):

+

+1) Vehicle or high‑current starter load

+

+- New battery (low internal resistance): turning the key holds voltage ≳11 V and the engine cranks easily.

+- Aged battery (internal resistance increased): voltage may collapse to ~9 V or lower on crank, motor may fail to turn.

+- Symptoms: weak cranking sounds, slow or no crank.

+

+2) Supplying an inverter / UPS under heavy load

+

+- New battery: inverter sustains heavy load and can deliver ≳80% of nominal capacity.

+- High‑resistance battery: voltage drops quickly under load, inverter alarms or shuts down early.

+- Symptoms: frequent alarms, early shutdown while capacity still remains in the battery.

+

+3) Electric scooter / light EV acceleration

+

+- New battery: small voltage dip on acceleration, smooth power delivery.

+- High‑resistance battery: large voltage drop on throttle, controller may trigger low‑voltage protection and cut power intermittently.

+- Symptoms: sudden power loss under acceleration, power returns when throttle is released.

+

+4) Charging behavior

+

+- New battery: accepts high charge current initially, charges efficiently.

+- High‑resistance battery: charge current is limited, charger may switch to float early and report a finished charge even though usable capacity is low.

+- Symptoms: charging appears to finish quickly but the battery discharges rapidly in use.

+

+

+## Testing methods

+

+Detecting capacity and health of used lead‑acid batteries can be divided into quick checks and accurate tests. Below is a complete procedure you can choose from depending on available tools.

+

+1) Quick checks (minutes)

+

+- Resting (open‑circuit) voltage — rough check:

+ - Charge fully, then rest for ~12 hours before measuring.

+ - ≳12.6 V: generally healthy

+ - 12.4–12.5 V: moderate degradation

+ - ≤12.3 V: likely aged or discharged

+ - Note: This only indicates state of charge/obvious aging, not true capacity.

+

+- Internal resistance test (recommended):

+ - Use a battery internal‑resistance meter (inexpensive handheld units to mid‑range testers).

+ - Example guidance:

+ - Small 12 V, 7 Ah battery: <20 mΩ healthy; 30–40 mΩ fair; >50 mΩ scrap.

+ - Automotive starting batteries: internal resistance is on the order of tens of milliohms; a noticeable increase vs. new indicates degraded performance.

+

+- Instant voltage‑drop (load) test — simple practical check:

+ - Connect a known heavy load (e.g., high‑beam headlight or ~100 W resistor) and observe the instantaneous voltage drop.

+ - New battery: drop typically ≤0.4–0.5 V

+ - Aged battery: instantaneous drop may exceed 1.0 V

+

+2) Accurate testing (hours)

+

+- Constant‑current discharge capacity test (gold standard):

+ - Fully charge the battery (use appropriate charger, e.g., 14.4 V CV for 12 V lead‑acid until absorption/current falls).

+ - Rest the battery with charger disconnected for ≥2 hours.

+ - Discharge at a constant current (recommended 0.05C–0.1C; e.g., for 100 Ah battery use 5–10 A) down to the cutoff voltage (commonly 10.5 V for 12 V batteries).

+ - Calculate capacity: Capacity (Ah) = Discharge current (A) × Discharge time (h).

+ - Example: 5 A discharge to 10.5 V took 15 h → capacity = 5 × 15 = 75 Ah. If measured capacity < 80% of rated, the battery is significantly aged.

+

+3) Good / bad reference (example thresholds)

+

+| Status | Resting voltage (12 V battery) | Internal resistance (automotive, mΩ) | Measured capacity | Conclusion |

+|----------|-------------------------------:|-------------------------------------:|------------------:|-----------|

+| Excellent| ≥ 12.6 V | ≤ 8 mΩ | ≥ 90% | Healthy |

+| Moderate | 12.4–12.5 V | 9–15 mΩ | 70–90% | Usable |

+| Poor | ≤ 12.3 V | 15–25 mΩ | 50–70% | Marginal |

+| Scrap | ≤ 12.0 V | ≥ 25 mΩ | < 50% | Replace |

+

+

+

+

+

+## ref

+

+

+

+# battery-tools-dat

+

+- [[battery-dat]] - [[fab-tools-dat]] - [[battery-tools-dat]] - [[battery-tester-dat]]

+

+- [[battery-pack-dat]]

+

+- [[Coulomb-Meter-dat]]

+

+- [[battery-drainer-dat]]

+

+- [[Kelvin-Clamp-dat]]

+

+### charger

+

+- [[battery-charger-dat]]

+

+

+

+## battery tools == for battery pack build

+

+### tools

+

+- [[fab-tools-dat]] - [[soldering-tools-spot-welding-dat]]

+

+- capacity - [[electronic-loader-dat]]

+- internal resistance == discharge current - [[internal-resistance-meter-dat]]

+

+[LittloKala M4S](https://www.liito-kala.com/page92?product_id=31)

+

+- CHARGE: Charges the battery to full

+- DISCHARGE: Discharge the battery to empty.

+- TEST: Test battery capacity.

+- STORAGE: Charge the battery voltage to 3.8V or discharge the battery voltage to 3.8V.

+

+

+### battery pack assembly materials

+

+- [[battery-pack-kit-dat]]

+

+- 1. Nickel Strip / copper strip == `铝片和铜片`，电池点焊用的，铝片适合铝壳电池，铜片适合铁壳电池 - [[fab-soldering-materials-dat]]

+

+

+- `青稞纸电池垫` == 使用在电池点焊前，贴在18650电池前，防止压迫导致电池塑料纸损坏，造成电池短路

+

+- 2. `青稞纸` == 青稞纸基本都是最后出场，作为电池绝缘和减震的重要部分

+

+- `硅胶电线` == 链接电池用的，硅胶耐高温，相比一般电线胶皮的上锡的时候不会融化。

+

+- 3. [[battery-holder-dat]]

+

+- 4. [[battery-BMS-dat]] - [[battery-manager-dat]]

+

+- 5. [[case-dat]] or [[heat-shrink-tube-dat]]

+

+

+## ref

+

+

+- [[battery-tools]] - [[battery]]

+

+

+# Coulomb-Meter-dat

+

+- [[fab-tools-dat]] - [[Coulomb-Meter-dat]] - [[battery-tools-dat]]

+

+A **Coulombmeter** (also spelled **Coulomb Meter** or called a **Coulomb Counter**), in the context of battery electronics, is a high-precision instrument or integrated circuit used to measure **electrical charge**.

+

+In everyday applications, it functions as a highly accurate "fuel gauge" for lithium-ion battery management systems (BMS) [[BMS-dat]] found in smartphones, laptops, drones, portable power stations, and electric vehicles (like scooters and rovers). It calculates exactly how much capacity is left in terms of percentage (%) and remaining runtime.

+

+---

+

+## 1. Core Operating Principle: The "Water Tank" Analogy

+

+Early battery-monitoring methods estimated battery capacity solely by measuring **cell voltage**. However, lithium-ion batteries have a very flat discharge curve—their voltage drops very little throughout most of their cycle, then plunges rapidly at the very end. This leads to inaccurate readings (e.g., a phone staying at 50% for hours, then suddenly dropping to 10% in minutes).

+

+A coulombmeter solves this by tracking the actual inflow and outflow of current over time, similar to a precise flow meter installed on a water pipe:

+* **During Charging:** It counts every milliampere of current flowing *into* the battery and multiplies it by time, calculating the added charge.

+* **During Discharging:** It counts every milliampere flowing *out* of the battery and subtracts it from the total.

+

+Technically, it measures the voltage drop across an ultra-low-resistance inline component called a **Shunt Resistor** (Current Sense Resistor). By sampling this current ($I$) continuously, it computes the total charge ($Q$) using mathematical integration over time ($t$):

+

+$$Q = \int I \, dt$$

+

+The final calculated output is expressed in standard battery units: **mAh (milliampere-hours)** or **Ah (ampere-hours)**.

+

+

+

+---

+

+## 2. Coulomb Counting vs. Traditional Voltage Estimation

+

+| Feature | Traditional Voltage Estimation | Coulomb Counter (Coulombmeter) |

+| :--- | :--- | :--- |

+| **Measurement Method** | Reads the instantaneous voltage across battery terminals. | Continuously logs net current entering/leaving the cell over time. |

+| **Accuracy** | **Low**. Heavily skewed by sudden loads, ambient temperature, and aging. | **Very High**. Accurately tracks minute changes in real-time power consumption. |

+| **Drop-off Phenomenon** | Prone to sudden percentage jumps or drops under heavy loads. | Delivers smooth, linear, and predictable percentage tracking. |

+| **Hardware Cost** | Zero extra cost (uses the microcontroller's internal ADC). | Higher cost (requires a dedicated chip and a precision shunt resistor). |

+

+---

+

+## 3. The Cumulative Error Challenge: Learning Cycles

+

+While highly accurate, coulombmeters suffer from a physical limitation known as **drift** or accumulated error. Because sensing resistors and ADC clocks have minor tolerances, keeping a battery perpetually between 30% and 80% without a full reset causes these tiny mathematical errors to compound over weeks, leading to drifted readings.

+

+To maintain accuracy, the system relies on a process called a **Learning Cycle**:

+> 💡 When the battery is charged to its absolute maximum limit (detected when charging current drops to a minimum threshold) or drained to its absolute safe cut-off voltage, the system automatically recalibrates and resets its baseline data to "100%" or "0%". This completely clears out any accumulated mathematical drift. This is why new electronic devices or DIY battery projects often require a full charge/discharge cycle upon initial setup to calibrate the fuel gauge.

+

+---

+

+## 4. Common Application Scenarios

+

+1. **Consumer Electronics:** Mobile devices, smartwatches, and laptops rely on dedicated gas-gauge ICs (e.g., Texas Instruments `BQ27421`). - [[BQ27421-dat]]

+2. **Portable Power Stations & Solar Storage:** Large-capacity lithium packs utilize external shunt-based coulombmeters to display exact remaining amp-hours or watts.

+3. **Robotics & DIY Projects (e.g., ESP32/Rover Smart Power Management):** Hardware developers add micro-chips like the `MAX17043` or integrated power modules to monitor exact power draw, prevent hazardous over-discharge conditions, and execute automated low-battery return-to-home functions. - [[MAX17043-dat]]

+4.

+

+

+

+## ref

+

+

+

+# electronic-loader-dat

+

+- [[KP182-dat]] - [[IT8511A-dat]]

+

+- [[battery-tools-dat]] - [[internal-resistance-meter-dat]] - [[electronic-loader-dat]] - [[lab-power-dat]]

+

+

+

+

+## mode: CC, CV, CW, CR

+

+

+

+

+## How to Test a 18650 Battery Capacity Using an Electronic Load

+

+### ✅ What You Need:

+- Electronic Load (DC electronic load, programmable preferred)

+- Fully charged 18650 battery

+- Battery holder or safe terminal connectors

+- Multimeter (optional, for voltage verification)

+- Logging software or notebook (if needed)

+

+---

+

+### ⚡ Step-by-Step Instructions

+

+#### 1. Fully Charge the Battery

+- Use a proper lithium-ion charger.

+- Ensure the voltage reaches **4.2V** before testing.

+

+#### 2. Connect the Battery

+- Insert the battery into a **18650 holder**.

+- Connect **positive (+)** to the load's positive terminal.

+- Connect **negative (−)** to the load's negative terminal.

+- Double-check for correct polarity.

+

+#### 3. Configure the Electronic Load

+- **Mode**: Constant Current (CC)

+- **Discharge Current**: e.g., **1.0 A**

+- **Cut-off Voltage**: e.g., **3.0 V** (to protect the cell)

+

+> ⚠️ Don't go below 2.5V to avoid damaging the battery.

+

+#### 4. Start the Discharge Test

+- Turn on the load.

+- The battery will begin discharging at the set current.

+- The load will stop automatically at the cut-off voltage.

+

+#### 5. Read the Results

+- Check the screen of the electronic load.

+- Look for:

+ - **Capacity (mAh)**

+ - **Energy (Wh)**

+ - **Total time**

+

+> Example output:

+> `Capacity: 2600 mAh`

+> `Energy: 9.5 Wh`

+

+---

+

+### 📌 Notes & Tips

+

+Test at room temperature (around 25°C) for accuracy.

+

+If the load doesn’t show capacity:

+

+ Capacity (mAh) = Current (A) × Time (h) × 1000

+

+ 0.5A for 1 hour == 0.5 x 1A = 500mAh

+

+ 0.5A for 1.2 hour = 600 mAh

+

+

+

+## ref

+

+# internal-resistance-meter-dat

+

+- [[battery-tools-dat]] - [[internal-resistance-dat]] - [[resistor-dat]]

+

+

+## Hioki Resistance Tester (Digital Low Resistance Tester / Micro-ohmmeter)

+

+A professional instrument for precise measurement of low or high-precision resistance in electrical equipment.

+

+**Features (sorted):**

+- High precision: Measures resistance from milliohms to megaohms with minimal error

+- Low resistance measurement: Accurate measurement of low resistance values (mΩ level) in motor windings, cables, contactors, and busbars

+- Portability & recording: Some models are handheld, with data storage and interface for exporting measurement records

+- Safety: Designed for live equipment or industrial environments; some models feature 4-wire (Kelvin) measurement

+

+**Applications (sorted):**

+- Contact resistance measurement in low-voltage distribution equipment

+- Maintenance and inspection of industrial electrical equipment

+- Motor winding testing

+- Transformer wiring inspection

+

+**English Names:**

+- Digital Low Resistance Tester / Micro-ohmmeter

+- Hioki Resistance Tester

+

+

+

+## version plus with multimeter

+

+- [[multimeter-dat]]

+

+UT70Acapa

+

+

+

+

+## TS457

+

+## ED1035

+

+testing - [[18650-dat]]

+

+80m ohm is really bad

+

+

+

+25m ohm is not bad

+

+

+

+

+

+

+## ref

+

+- [[battery-pack-dat]]

+

+- [[internal-resistance-meter]]

+