📖 Glossary
Terms, abbreviations, and definitions used throughout this study.
Contents
Battery & Electrochemistry
| Term |
Definition |
| LiFePO₄ |
Lithium Iron Phosphate — a lithium-ion battery chemistry known for safety, longevity, and thermal stability. Also written as LFP. |
| 4S Configuration |
Four cells connected in Series, producing ~12.8V nominal (3.2V × 4). |
| Parallel Configuration |
Multiple cells or blocks connected positive-to-positive and negative-to-negative, increasing capacity while maintaining voltage. |
| BMS |
Battery Management System — circuitry that monitors cell voltages, temperatures, and current, providing protection against overcharge, overdischarge, and overcurrent. |
| SOC |
State of Charge — the remaining capacity of a battery expressed as a percentage of its full capacity. |
| OCV |
Open Circuit Voltage — the voltage measured across battery terminals with no load connected and after sufficient rest time. |
| Nominal Voltage |
The typical operating voltage of a battery chemistry; 3.2V per cell for LiFePO₄. |
| Capacity (Ah) |
Ampere-hours — a measure of how much charge a battery can store. A 100Ah battery can theoretically deliver 100A for 1 hour or 10A for 10 hours. |
| Internal Resistance |
The opposition to current flow within a battery, measured in milliohms (mΩ). Lower is better. |
| Peukert Exponent |
A constant (k) describing how capacity decreases at higher discharge rates. k = 1.0 is ideal (no capacity loss); LiFePO₄ is typically 1.00–1.05. |
| Parasitic Draw |
Small continuous current consumption from connected devices when the system is nominally “off.” |
| Self-Discharge |
The gradual loss of charge in a battery when not in use, due to internal chemical reactions. LiFePO₄ has very low self-discharge (~2–3% per month). |
Statistics & Analysis
| Term |
Definition |
| OLS |
Ordinary Least Squares — a standard linear regression method that minimizes the sum of squared differences between observed and predicted values. |
| R² |
Coefficient of Determination — indicates how well the regression line fits the data. R² = 1.0 means perfect fit; R² = 0 means no linear relationship. |
| σ (Sigma) |
Standard Deviation — a measure of the spread or dispersion of a dataset. Lower σ means data points are closer to the mean. |
| SE |
Standard Error — the standard deviation of a statistic’s sampling distribution. Often reported for regression coefficients. |
| p-value |
The probability of observing results at least as extreme as measured, assuming the null hypothesis is true. Typically, p < 0.05 is considered statistically significant. |
| MA-60s |
Moving Average, 60 Seconds — a time-based trailing rolling mean applied to high-frequency data. Uses rolling('60s') in pandas, which adapts to variable sampling intervals. |
| Detrended |
Data with the linear trend removed, allowing analysis of residual variation around the trend. |
| Residual |
The difference between an observed value and the value predicted by a model. |
| Window Dependence |
The phenomenon where calculated statistics (like drift rate) vary depending on the time window selected for analysis. |
Hardware & Sensors
| Term |
Definition |
| Shelly Plus Uni |
A Wi-Fi-enabled sensor interface by Shelly, used here for voltage monitoring. Features ESP32 microcontroller with integrated ADC. |
| ADC |
Analog-to-Digital Converter — circuitry that converts continuous analog signals (like voltage) into discrete digital values. |
| ESP32 |
A popular microcontroller by Espressif with integrated Wi-Fi and Bluetooth, used in the Shelly Plus Uni. |
| Vref |
Reference Voltage — the known voltage that an ADC uses as a comparison standard. ESP32 has nominal 1100mV Vref with chip-to-chip variation of 1000–1200mV. |
| eFuse Calibration |
Factory calibration values burned into ESP32 chips that can improve ADC accuracy. |
| Home Assistant |
Open-source home automation platform used for data collection, logging, and integration in this study. |
| InfluxDB |
A time-series database often used with Home Assistant for long-term data storage. |
| Eco Mode |
A power-saving mode on Shelly devices that reduces power consumption but may affect sampling behavior. Enabled Dec 23, 2025 in this study. |
Data & Measurement
| Term |
Definition |
| Hourly Aggregate |
Data summarized per hour, typically as minimum, maximum, or mean values within that hour. |
| High-Frequency Data |
Raw sensor readings at the fastest available rate (~3 seconds in this study). |
| State-Change Logging |
A logging method where new records are only created when the measured value changes. Results in variable time intervals between records. |
| Cadence |
The timing interval between measurements. Can be fixed (e.g., every 10 seconds) or variable (state-change logging). |
| Spread |
The difference between maximum and minimum values within a time window. In this study: Spread = Max - Min for hourly data. |
| Mid-Voltage |
The arithmetic mean of minimum and maximum voltage: Mid = (Min + Max) / 2. |
| Quantization |
The discrete steps in ADC output. A 10mV quantization means the sensor can only report values in 10mV increments. |
| EMI |
Electromagnetic Interference — unwanted electrical noise that can affect sensor readings. |
| Artifact |
An anomaly in data caused by the measurement system rather than the phenomenon being measured. |
Units & Conversions
| Unit |
Name |
Notes |
| V |
Volts |
Electrical potential difference |
| mV |
Millivolts |
1 mV = 0.001 V |
| A |
Amperes |
Electrical current |
| mA |
Milliamperes |
1 mA = 0.001 A |
| Ah |
Ampere-hours |
Battery capacity |
| mΩ |
Milliohms |
Resistance (1 mΩ = 0.001 Ω) |
| °F |
Degrees Fahrenheit |
Temperature (used in this study) |
| °C |
Degrees Celsius |
Temperature (°C = (°F - 32) × 5/9) |
| UTC |
Coordinated Universal Time |
Standard time reference for high-frequency data |
| EST/EDT |
Eastern Standard/Daylight Time |
Local time zone for hourly data (UTC-5/UTC-4) |
Temperature Conversion
°C = (°F - 32) × 5/9
°F = (°C × 9/5) + 32
Common Values
| Description |
Value |
| LiFePO₄ cell nominal voltage |
3.2 V |
| LiFePO₄ cell full charge |
3.65 V |
| LiFePO₄ cell empty |
2.5 V |
| 4S pack nominal |
12.8 V |
| 4S pack full charge |
14.6 V |
| 4S pack empty |
10.0 V |
| Freezing point (charge cutoff) |
32°F / 0°C |
See Also