What is the difference between dry batteries and wet batteries?
2 Answers
These two types of batteries differ in the following ways: Dry batteries belong to the primary cells in chemical power sources and are disposable batteries. Because the electrolyte in this type of chemical power device is a non-flowing paste, it is called a dry battery, which is in contrast to batteries with flowable electrolytes. Battery water can be added, but it should not exceed the maximum water level, usually marked with a MAX line. Dry-charged batteries (such as automotive dry-charged batteries, motorcycle dry-charged batteries, etc.) require the addition of distilled water after a period of use to maintain the density of the dilute sulfuric acid electrolyte at around 1.28g/ml. As for maintenance-free batteries, they do not require the addition of distilled water until the end of their service life. Wet batteries are lead-acid batteries, formed by a sulfuric acid electrolyte solution. Generally speaking, for 80% of batteries, they can be distinguished by color: white indicates a wet battery, while black indicates a dry battery. In terms of weight, lighter ones are wet batteries, and heavier ones are dry batteries. From the appearance and accessories, batteries with water-filling screws are wet, while flat-top ones are dry. Lead-acid batteries are mainly divided into three categories: Ordinary batteries: The plates of ordinary batteries are made of lead and lead oxides, with the electrolyte being an aqueous solution of sulfuric acid. Their main advantages are stable voltage and low cost; the disadvantages are low specific energy (i.e., the amount of electrical energy stored per kilogram of battery), short service life, and frequent daily maintenance. Dry-charged batteries: Their full name is dry-charged lead-acid batteries. Their main feature is that the negative plate has a higher storage capacity of 2V lead-acid batteries. In a completely dry state, they can retain the obtained charge for two years. When in use, only the electrolyte needs to be added, and after about 20-30 minutes, they can be used. Maintenance-free batteries: Due to their structural advantages, maintenance-free batteries consume very little electrolyte and generally do not require the addition of distilled water during their service life. They also have the characteristics of being shock-resistant, high-temperature resistant, compact in size, and having low self-discharge. Their service life is usually twice that of ordinary batteries. There are also two types of maintenance-free batteries on the market: The first type is filled with electrolyte once at the time of purchase and does not require maintenance (adding supplementary fluid) during use; the other type is already filled with electrolyte and sealed when leaving the factory, and users cannot add supplementary fluid at all.
I've been driving for over a decade and have used both dry cell and wet cell batteries. The difference between these two is quite noticeable. Dry cell batteries are maintenance-free, with the electrolyte sealed in fiberglass mats during manufacturing. You don't need to add water regularly - just install and use. Wet cell batteries require periodic distilled water top-ups, otherwise the plates can get damaged. Two years ago, my dry cell battery started the car smoothly at -20°C in northeast China, while the wet cell battery struggled in the cold. However, wet cell batteries are much cheaper - only about 200 yuan to replace, compared to 600-700 yuan for dry cell batteries. In terms of lifespan, dry cell batteries last 5-6 years, while well-maintained wet cell batteries can last about 4 years. I remember once forgetting to add water to a wet cell battery, and it died after just two years - what a waste! The choice depends on your needs: go for dry cell for convenience, or wet cell for cost savings.
