“Dry” (Maintenance-Free) Battery Sudden Failure — Causes and Solutions?

Sudden failure is a major drawback of maintenance-free batteries (often referred to as “dry” batteries). So what is the true nature of this type of battery, and how can the risk of sudden failure be reduced?

Maintenance-free batteries have a structure and operating principle similar to conventional batteries. Inside, they contain positive/negative plates made from lead–calcium alloy, separators,and a dilute sulfuric acid electrolyte.

During use, when the battery is being charged, the electrolyte can boil. Although the battery is sealed, in many cases gas can still escape, causing the electrolyte level to drop and eventually run low.

When operating at high temperatures with insufficient electrolyte, the plates can warp, crack, lose their connections, or short-circuit—this is when a battery can fail suddenly. Conventional batteries are different: if the electrolyte level drops but is replenished regularly and adequately, they will not suffer sudden failure.

To reduce the risk of sudden failure, vehicle owners should avoid installing unnecessary additional electrical devices. In addition, if the car is left unused for a long time, the engine should be started weekly and left idling for about 15–20 minutes.

Each type has its own advantages and disadvantages. Maintenance-free batteries are convenient to use, but you have to accept a higher risk compared with conventional batteries. What do you think? Please share your experience.