Dry-charged batteries

Freshly assembled cells are subjected to a series of formation cycles in order to activate the system. Cells are often sold in a charged but dry state, in which case the formation process is performed before the final cell assembly. Dry charged batteries can be stored indefinitely. Cells containing electrolyte should be stored in the completely discharged state since dissolution of silver oxide is then avoided. 

Dry-charged battery — Batteries that are shipped and stored in the charged state, but dry and free of electrolyte. Under such conditions the batteries exhibit very long shelf life, and can be rapidly activated by introducing the electrolyte upon demand. Silver-oxide based bat-... 

Dilute sulfuric acid has tp be added to dry charged batteries at service stations to activate a battery. You are asked to prepare a batch of new acid as follows. A tank of old weak battery acid (H2SO4) solution contains 12.43% H2SO4 (the remainder is pure water). If 200 kg of 77.7% H2SO4 is added to the tank, and the final solution is 18.63% H2SO4, how many kilograms of battery acid have been made See Fig. E2.13. 

This manufacturing process is employed for the production of dry charged batteries. These batteries are ready for use after adding the sulfurie acid solution with no need of preliminary charging. The shelf life of these batteries is more than 1 year. 

The next section of this chapter will concentrate mainly on the energy losses observed during the different technological operations involved in the manufacture of dry-charged batteries. 

Battery manufacturers have encountered a rather strange phenomenon during manufacture of dry-charged batteries, namely the discharge voltage of the battery decreased abruptly with... 

Internal resistance of dry-charged batteries as a function of plate drying temperature. Curve (A) cells with thoroughly washed plates curve (B) cells with plates after only rinsing off the acid [4]. 

Quality Control Monitoring During Manufacture of Dry-charged Batteries... 

The quality of the plates for dry-charged batteries should be monitored during the production process by measuring definite control parameters at least once a day. Only if the measured parameters meet the respective requirements, can these plates be assembled into batteries. The control parameters subject to inspection include the following ... 

Discharge transients for positive plates of dry-charged batteries after 2 years of storage discharge... 

Separator. The separators of dry-charged batteries are not affected during storage. 

The processes that proceed in dry-charged batteries during storage depend strongly on the moisture content in the plates and separators. At moisture contents up to 0.2%, these processes proceed at a low rate, but at 0.6—1.0% moisture levels, the energy losses of the plates increase. To keep down the moisture level and thus increase the shelf-life of dry-charged batteries, some manufacturers add a certain amount of siUca-gel desiccant to each cell. 

When batteries have been dry-charged, they have to be reactivated before use. Activation consists of unpacking the battery, filling the cells with electrolyte (which sometimes is shipped with the battery in a separate package), charging the battery (if time is available), and testing the battery performance. When dry-charged batteries are activated, the materials which had been used to seal the vent holes must be removed and discarded. 

Dry Charged Battery A battery in which the electrodes are in a charged state, ready to be activated by the addition of the electrolyte. 

---