its not that easy first is this DCR or ACR?
I would suprised if it is measureing DCR. ACR is a lot easier to measure. But eaither way the improtant item is not some much the value but how it changes over time. If tis is DCR that is a very good charger.
in the context of LiPo batteries (Lithium Polymer batteries), DCR and ACR refer to different measurements of internal resistance, which is a critical indicator of a battery's performance and health.
DCR (Direct Current Internal Resistance)
What it is: DCR measures the battery's internal resistance when a direct current (DC) load is applied. It's often calculated by applying a short pulse of high current (discharge or charge) and then measuring the voltage drop across the battery terminals. Ohm's Law (R = V/I) is then used to determine the resistance.
What it includes: DCR encompasses all the resistive components within the battery, including:
Ohmic resistance (R0): This is the instantaneous resistance from the electronic components, electrode materials, electrolyte, diaphragm, and contact resistance.
Polarization resistance (Rp): This accounts for the slower voltage drops due to electrochemical polarization and concentration polarization, which involve the movement of ions.
How it's measured: Standardized methods like IEC 61960 often involve applying a discharge pulse (e.g., 0.2C for 10 seconds, then 1C for 1 second) and calculating the DCR from the voltage and current differences.
Significance:
DCR is a crucial indicator for evaluating a battery's power capability and cycle life. A lower DCR generally means a battery can deliver more current with less voltage drop.
It varies with the battery's State of Charge (SoC), State of Health (SoH) (aging), and temperature. As a battery ages, its DCR typically increases.
It's particularly relevant for applications where constant, high DC current is drawn, like in electric vehicles or power tools.
ACR (Alternating Current Internal Resistance)
What it is: ACR measures the battery's internal resistance using an alternating current (AC) signal, typically at a specific frequency (e.g., 1 kHz or 100 Hz). Instead of a DC load, a small AC current is injected, and the resulting AC voltage response is measured to determine the impedance. Only the "real" part of the impedance (resistance) is considered for ACR.
What it includes: ACR primarily reflects the ohmic resistance (electronic and ionic resistance) of the battery, as the high frequency of the AC signal doesn't give the slower chemical and diffusion processes time to significantly contribute to the impedance.
How it's measured: ACIR measurement equipment applies a small AC current and measures the AC voltage, then calculates the impedance (Z = Vac / Iac).
ACR is often the "internal resistance" value quoted in battery datasheets because it's a quick and relatively easy measurement.
It's useful for cell sorting in battery pack manufacturing, as it provides a consistent and comparable value for initial cell quality.
While it's a good indicator of instantaneous electronic and bulk electrolyte resistance, it doesn't fully capture the complex electrochemical processes that contribute to voltage drop under real-world DC loads.
A rule of thumb is that ACR is approximately 70% of the DCR value for the same cell.
Yes I am a battery nerd.
Topic: Battery resistance?? (Read 345 times)