AGM batteries use a closed valve-controlled design, and their internal structure does not allow direct water addition. This type of battery is sealed, and there is an exhaust valve on the battery cover, and no water is required during normal use. Unlike conventional non-sealed batteries, AGM batteries are more advanced in design and use, and do not need to be frequently replenished with water like traditional batteries. Therefore, there is no water inside the AGM battery, but a pure aqueous sulfuric acid solution is used as the electrolyte. The density of this electrolyte is usually between 1.29-1.31g/cm3, most of which exists in the glass fiber membrane, and a part of the electrolyte is also absorbed inside the plate12.
In addition, due to its fully sealed characteristics, AGM batteries show good waterproof performance in the case of wading or other liquid contact, and the performance will not be affected by water ingress. Nevertheless, if the vehicle wades, it is recommended to clean and check the battery in time to ensure its health and performance.
