The design is more complex and the manufacturing process is more involved than for flat pasted plates. The manufacturing process starts with the production of the grid which is usually a series of fifteen parallel lead rods or spines cast on to a bar. This is usually fabricated from 6-10% antimonial lead alloy.
Following the casting process, a series of parallel porous glass fiber tubes are fitted over the grid spines, these tubes are then filled with a mixture of lead oxide and red lead powder by vibration. Once the tubes are filled, they are sealed by knocking a plastic fitting onto the ends of the lead grid spines. The resulting assembly is then “pickled” by soaking in dilute sulfuric acid to convert the lead oxides to lead sulfate. The finished product comprises a series of tubes filled with lead sulfate with a center core of lead to carry the current.
Compared to the processes used to make flat pasted plates, this has considerably more steps and is more difficult to control.
Batteries made from tubular plates have the following characteristics:
1. GOOD ELECTRICAL PERFORMANCE
2. ADEQUATE LIFE
3. LOW RESERVE OF LEAD
4. LOW RESERVE OF ACTIVE MATERIAL
5. SENSITIVE TO ACTIVE MATERIAL SHEDDING WHICH SHORTENS CELL LIFE
6. SENSITIVE TO TOP BAR BREAKAGE WITH SIGNIFICANT LOSS OF PLATE AREA
7. SENSITIVE TO SPINES BEING OFF CENTER OF THE TUBE WITH SIGNIFICANT LOSS OF PLATE CAPACITY