OVERCHARGING

NZ Truth, Issue 1152, 29 December 1927, Page 13

OVERCHARGING

Chemical Injury To

Plates

The question whether overcharging does or does not injure a battery is one which closely concerns the owner driver, who often wants to know whether he should always keep the battery on charge

whatever its condition

THE question was recently dealt with by the chief engineer of a wellknown battery manufacturing concern, who pointed out that overcharging does harm in several ways. The lowering of the electrolyte level by excessive decomposition will, unless made good, uncover the upper portion of the plates and increase the current density on the covered portion of the plates, resulting in overheating and abnormal depreciation.

In certain batteries in which the plates are not protected by a complete diaphragm, lead sulphate carried up- by the circulating electrolyte will form spongy lead on the upper edges or on projecting ledges, and in time bridge across and short

circuit the. plates. The plates also suffer material damage, the active material of the negative plates contracting and the grids of the positives becoming oxidized and, furthermore, the active 'material of the positive plates suffer from mechanical and chemical effects. Overcharging, therefore, does cajise increased depreciation.