The internal resistance of lead-acid batteries is a key characteristic that has a significant impact on their overall performance, especially power output.
First, the internal resistance of lead-acid batteries consists of multiple components. The ohmic internal resistance mainly comes from the resistance of the plates, electrolyte, connecting parts, etc. Its size is relatively stable, but it will change with factors such as battery aging and plate corrosion. The polarization internal resistance is related to the chemical reaction process of the battery, including electrochemical polarization and concentration polarization. Electrochemical polarization is caused by the accumulation of charge on the electrode surface due to the limited electrochemical reaction rate; concentration polarization is caused by the difference between the change in ion concentration near the electrode and the bulk solution. These different types of internal resistance interact with each other and together constitute the total internal resistance of lead-acid batteries.
Secondly, internal resistance has a direct limiting effect on the power output of lead-acid batteries. According to the power output formula P = U² / (R + r) (where P is power, U is the battery electromotive force, R is the external load resistance, and r is the battery internal resistance), the larger the internal resistance, the smaller the power that the battery can output under the same electromotive force and load resistance. For example, when starting a high-power device, such as when an electric car starts or when a power tool is working, a large current output is required. At this time, the internal resistance will cause the battery terminal voltage to drop significantly, the power output is limited, and the device may not start normally or operate inefficiently. Moreover, as the battery discharge process proceeds, the internal resistance will gradually increase, further exacerbating the attenuation of power output.
Furthermore, temperature has a significant effect on the internal resistance of lead-acid batteries. Generally speaking, when the temperature decreases, the viscosity of the electrolyte increases, the ion diffusion rate slows down, and the ohmic internal resistance and polarization internal resistance increase. This makes the power output capacity of lead-acid batteries drop significantly in low temperature environments, which is also an important reason for the difficulty of starting cars in winter. On the contrary, appropriately increasing the temperature can reduce the internal resistance and increase the power output, but too high a temperature will accelerate the aging of the battery plate and the evaporation of the electrolyte, so it is necessary to accurately control the battery operating temperature range.
Finally, in order to reduce the limitation of internal resistance on power output, you can start from many aspects. For example, optimize the plate design and manufacturing process to improve the conductivity of the plate; develop new electrolyte formulas to reduce ion transfer resistance; use a suitable battery management system to monitor changes in battery internal resistance in real time and perform temperature control and balanced charging to maintain the battery internal resistance at a low level, thereby ensuring the efficient power output of lead-acid batteries in various application scenarios.
