meter

-- [[internal-resistance-meter-dat]] - [[tools-dat]]

-- [[internal-resistance-meter-dat]]

-https://www.electrodragon.com/product/three-wires-dc-voltmeter-0-99-9v-wreverse-polarity-protection/

-- [[fab-tools-dat]]

-- [[sensor-voltage-dat]] - [[meter-voltage-dat]] - [[SVC1049-dat]] - [[SVC1017-dat]]

-

-- [[internal-resistance-meter-dat]]

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

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

-

-

-# 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

-

-

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

-- [[meter-current-dat]] - [[meter-voltage-dat]] - [[meter-inductor-dat]] - [[internal-resistance-meter-dat]] - [[meter-power-dat]]

-# 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]]

-

-- [[tools]]

-

-

-# meter-current-dat.md

-

-== memter am

-

-== ammeter == ampere meter == current meter

-

-- [[sensor-voltage-dat]] - [[meter-voltage-dat]] - [[SVC1049-dat]] - [[SVC1017-dat]]

-

-- [[sensor-current-dat]] - [[meter-current-dat]] - [[SVC1022-dat]] - [[SVC1023-dat]]

-

-

-## board

-

-- [[meter-voltage-dat]] - [[SVC1019-dat]] - [[SVC1049-dat]] - [[SVC1017-dat]] - [[SVC1015-dat]]

-

-

-

-

-

-- [[meter-current-dat]] - 10A [[SVC1022-dat]] - 50A [[SVC1023-dat]] - 100A [[SVC1024-dat]]

-

-- [[SVC1000-dat]] - [[SVC1002-dat]] - [[SVC1004-dat]] - [[ACS712-dat]]

-

-

-## ref

-

-- [[meter-current-dat]] - [[meter-voltage-dat]]

-

-

-

-# meter-resistance-dat

-

-

-## SCH

-

-

-

-

-

-

-

-## ref

-

-

-# meter-voltage-dat.md

-

-- [[fab-tools-dat]]

-

-- [[sensor-voltage-dat]] - [[meter-voltage-dat]] - [[SVC1049-dat]] - [[SVC1017-dat]]

-

-- [[sensor-current-dat]] - [[meter-current-dat]] - [[SVC1022-dat]] - [[SVC1023-dat]]

-

-

-

-## board and apps

-

-- [[meter-voltage-dat]] - [[SVC1019-dat]] - [[SVC1049-dat]] - [[SVC1017-dat]] - [[SVC1015-dat]]

-

-- [[meter-current-dat]] - [[SVC1022-dat]] - [[SVC1023-dat]] - [[SVC1024-dat]]

-

-- [[meter-resistance-dat]] - [[multimeter-dat]]

-

-## wiring

-

-

-

-

-## high voltage meter

-

-- [[high-voltage-dat]]

-

-

-

-

-

-## simple voltage meter

-

-

-

-

-

-## ref

-

-- [[meter-current-dat]] - [[meter-voltage-dat]]

-

-# multimeter-dat

-

-

-DMM == A Digital Multimeter (DMM) is an essential, handheld or benchtop electronic tool used to measure electrical values like voltage, current, and resistance with high accuracy.

-

-

-

-## good list

-

-

-- [[fluke-dat]] - [[Agilent-dat]] Agilent (安捷伦)

-

-- [[Klein-tools-dat]] - [[Extech-dat]] - [[Amprobe-dat]]

-

-- [[UNI-Trend-dat]] - [[mastech-dat]]

-

-- [[victor-dat]]

-

-

-

-## prerequisite

-

-- make sure the testing probe is GOOD, otherwise the measurement will be wrong.

-

-

-## bad list

-

-| | Model | Type/Style | mark | Issue/Note |

-| ---------------- | ------------ | -------------------- | ---- | ------------- |

-| [[UT-trend-dat]] | UT116C | SMD tester | bad | slow response |

-| | winAPEX 118A | Pen-style multimeter | bad | slow response |

-| [[UT-trend-dat]] | UT89XD | General multimeter | ?? | ?? |

-| [[victor-dat]] | VC9808+ | General multimeter | | |

-| [[victor-dat]] | VC830L | General multimeter | | |

-| [[victor-dat]] | VC921 | General multimeter | bad | slow respone |

-

-[[UT-trend-dat]] - UT70B/UT70A/UT70C/UT70D

-

-- [x] [[inductor-dat]]

-

-

-

-

-

-

-## function check list

-

-- [[inductor-dat]]

-

-

-

-

-## DM3058/E Series

-

-DM3058 / DM3058E is an economical 5.5-digit digital multimeter. It is designed for the test requirements of high accuracy, multi-function and automatic measurement. It integrates the functions of automatic measurement, multiple mathematical transformations and any sensor measurement. It provides USB, GPIB (DM3058 only), LAN (DM3058 only) and RS232 interfaces.

-

-https://eu.rigol.com/eu/products/DM_Detail/DM3058

-

-

-## design

-

-- [[voltage-reference-dat]] - [[TI-voltage-reference-dat]] - [[TI-dat]]

-

-- [[sensor-dc-voltage-dat]] - [[sensor-dc-current-dat]] - [[multimeter-dat]]

-

-- [[meter-resistance-dat]]

-

-## ref

-

-- 优利德旗下品牌 - 米尼帕ET-2652数字万用表

-

-- [[instrument-dat]] - [[fab-tools-dat]]