Battery internal resistance is the opposition to the flow of electric current <4> from within the battery itself, typically measured in ohms (Ω) or milliohms (mΩ).

Why Low Internal Resistance is Better

• Better Performance: Lower resistance lets the battery deliver high currents smoothly without a massive drop in voltage.

• Less Heat: Low resistance means less energy is wasted as heat, making the battery run cooler and more efficiently.

• Faster Charging: Batteries with low impedance handle higher charging currents safely and quickly.

• Longer Lifespan / Health Indicator: High internal resistance usually means the battery is old, worn out, damaged, or of low quality.