What Causes Battery Bulging?

[FinleyLee]

Automotive battery bulging can occur due to the following reasons: 1. In valve-regulated sealed lead-acid batteries during charging operations, especially in series-connected battery packs, overcharging can lead to poor internal gas recombination in low-quality batteries, resulting in bulging. To prevent this, when using valve-regulated sealed lead-acid batteries, it is advisable to reduce the float charge voltage and charging current, and avoid using poor-quality batteries. 2. Setting the float charge voltage too high with a large charging current accelerates oxygen evolution on the positive plate, which cannot recombine quickly enough at the negative plate. Additionally, the battery's internal temperature rises rapidly. If venting is delayed, the pressure may build up to a point where the valve-regulated sealed lead-acid battery bulges or deforms.