1. Battery Identification

    Before handling any power source, you must determine its chemical composition, voltage rating, and capacity. Misidentifying a battery type can lead to improper charging, chemical leaks, or thermal runaway.
    Chemistry Nominal Voltage Common Use Cases Key Characteristics
    Lead-Acid (Flooded/AGM/Gel) 2.1\text{V} per cell (6\text{V}, 12\text{V} standard) Automotive, UPS backups, solar storage Heavy, high surge current, requires venting if flooded.
    Lithium-Ion (Li-ion / LiFePO4) 3.2\text{V} to 3.7\text{V} per cell Electronics, power tools, EV, modern solar Lightweight, high energy density, requires a Battery Management System (BMS).
    Nickel-Metal Hydride (NiMH) 1.2\text{V} per cell Rechargeable household batteries (AA, AAA) Moderate self-discharge, robust, replaces legacy NiCd safely.
    • Label Inspection: Locate specifications for Nominal Voltage (V), Capacity (Ah or mAh), and Discharge Current Limits (C-rate) printed on the casing.
    • Physical Cues: Check for safety warning icons, recycling codes (e.g., Li-ion, Pb), and terminal markings.
    1. Battery Testing
      Testing evaluates state-of-charge (SoC), internal resistance, and overall health under load.
    • Open-Circuit Voltage (OCV) Test:
    • Set a digital multimeter to DC Voltage (V).
    • Connect the red probe to the positive terminal (+) and the black probe to the negative terminal (-).
    • Compare the measured value against manufacturer specifications (e.g., a fully charged 12\text{V} lead-acid battery reads roughly 12.6\text{V} or higher; a depleted one drops below 11.8\text{V}).
    • Load Testing: Measures voltage sag under a heavy electrical load to check if the battery can sustain current output. A healthy battery maintains stable voltage, whereas a degraded battery experiences a severe voltage drop.
    • Internal Resistance Check: Advanced battery analyzers send an AC signal through the cells to measure resistance (m\Omega). Rising internal resistance indicates aging, sulfation, or degradation.
    1. Battery Connections
      How batteries are wired changes the electrical output to match specific voltage and capacity requirements.
    • Series Connection (Increasing Voltage):
    • Connect the positive (+) terminal of the first battery to the negative (-) terminal of the next.
    • Result: Voltages add together while the capacity (Ah) remains the same.
    • Example: Two 12\text{V}, 100Ah batteries wired in series yield a 24\text{V}, 100Ah output.
    • Parallel Connection (Increasing Capacity):
    • Connect all positive (+) terminals together and all negative (-) terminals together.
    • Result: Capacity (Ah) adds together while the voltage remains the same.
    • Example: Two 12\text{V}, 100Ah batteries wired in parallel yield a 12\text{V}, 200Ah output.
    • Connection Safety Best Practices:
    • Always wear insulated tools and eye protection.
    • Clean corrosion off terminals before fastening clamps or lugs to ensure low contact resistance.
    • Tighten connections to manufacturer-specified torque