In battery management systems, a common question arises: how can thin sampling wires handle voltage monitoring for large-capacity cells without issues? The answer lies in the fundamental design of Battery Management System (BMS) technology. Sampling wires are dedicated to voltage acquisition, not power transmission, similar to using a multimeter to measure battery voltage by contacting terminals.
For a 20-series battery pack, the sampling harness typically has 21 wires (20 positives + 1 common negative). Each adjacent pair measures a single cell's voltage. This process isn't active measurement but a passive signal transmission channel. The core principle involves high input impedance, drawing minimal current—typically microamperes (μA)—which is negligible compared to cell capacity. According to Ohm's Law, with μA-level currents and wire resistance of a few ohms, voltage drop is merely microvolts (μV), ensuring accuracy without affecting performance.
However, proper installation is critical. Incorrect wiring—like reverse or cross-connections—can cause voltage errors, leading to BMS protection misjudgment (e.g., false over/under-voltage triggers). Severe cases may expose wires to high voltages, causing overheating, melting, or BMS circuit damage. Always verify the wiring sequence before connecting the BMS to prevent these risks. Thus, thin wires are sufficient for voltage sampling due to low current demands, but precision installation ensures reliability.
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