3D drawing of a complete formation line
3D drawing of a complete formation line

Revolutionizing Battery Formation: Formation in just 6 hours

A new fast formation technology (VACForm) for AGM batteries as well as flooded batteries has been developed and tested successfully.

The new fast formation process has been developed from the Engineering Office Dr. Nitsche together with Münstermann.

Underlying process

At the boiling point of water the latent heat of 540 kcal/kg water is stabilizing the temperature of the sulfuric acid. Water will be evaporated to keep the temperature at the boiling point. The boiling point of water depends on the applied pressure. The interesting temperature range of 50-60 °C equal the vacuum range of 120-200 mbar. To keep the battery at about 55-60 °C the formation takes part at 120-200 mbar. Due to the applied vacuum the gas and acid exchange is enforced giving rise to approximate 20-25% saving of electricity. Test results with a formation factor of 1.5 instead of typically 2.0 in traditional technology did show complete formation.

Very short formation time

The formation time for AGM 90 Ah batteries (L5) take about 6 h. An electrolyte supply vessel on top of the battery encloses the water being evaporated and decomposed during the formation. A vacuum chamber to test AGM or flooded batteries is available in the Münstermann test centre. This allows the customers to run a formation under specified conditions in vacuum and to test the batteries afterwards to the respective performance tests in their own laboratories.

Calculating water loss

The water loss due to water decomposition and especially the evaporated water due to chemical heat as well as Ohm's heat can be calculated using special program. Additional to the Ohm's water loss heat due to chemical reaction and water decomposition due to Coulomb's law will be calculated. It also calculates the volume and gravity of the filling acid depending on the final gravity and design of the AGM battery.

Münstermann manufactures production units

A typical unit exhibits 144 batteries with 18 batteries on 8 palettes. For a cycle time of 6 h 576 batteries / day and chamber can be formed.

Handling and process automation

To achieve an immediate start of formation after filling of acid to the batteries or a defined soaking time before start of formation, the acid is filled first into the cap containers and kept off the batteries. The batteries with acid filled cap container are loaded on palettes and connected with cables. Thereafter they are transferred into the VACForm chambers.

In the VACForm chambers the batteries are automatically connected to the rectifiers. The applied vacuum opens the valves in the cap container bottom and the acid is filled into the batteries. The formation can be started immediate or after a defined soaking time. In any case, all batteries show the acid at the same time and the temperature will be controlled for all batteries from the beginning on. Different to formation of batteries in water bathes all cells show the same temperature. In water bathes the two cells with the posts are better cooled being of very interest especially for AGM batteries.