What is Battery Formation?

What does “Battery Formation” Mean?

Battery formation is that step in battery production where the battery is prepared to receive an electrical charge and then charged or formed. The forming process is critical to the performance and lifespan of a battery. But as we will describe, it involves far more than simply connecting the battery to a power supply.

Battery formation occurs after the positive and negative plates have been produced. It can be performed with the plates installed in the battery case or prior to their installation. After formation, the battery undergoes final assembly and is ready for shipment. 

Formation is often the bottleneck in battery production. The process can take up to two to three days as it is labor intensive if automated formation equipment is not used.

What Happens During Lead-Acid Battery Formation?

During the battery formation process, the first chemical reaction occurs which prepares the battery to receive an electrical charge. After the plates have been finished and prepared, they are immersed—singly or in positive/negative pairs–into a solution of sulfuric acid for several hours.

The reaction between the lead and sulfuric acid causes layers of lead sulfate to form on the plate surfaces. This formation of lead sulfate is critical to the electrochemical reaction that allows a battery to do its job. Industry research reveals that carefully managing variables such as acid concentration and soak time can significantly improve battery performance. 

The next step is the actual forming step. In this step, electrical current is introduced to the battery. There are two types of formation: dry formation and wet formation. In dry formation, the plates are charged outside of the battery case in a large tank of electrolyte solution. Wet-formed batteries are charged inside the battery case.

During wet formation, the battery cases are often submerged in a water bath. This is done because of the large amount of heat produced while the battery is being charged. Subjecting the battery to high temperatures during forming is known to decrease the battery’s effectiveness and lifespan.

The actual charging process consists of a series of charges and breaks between charges. The initial charging process can easily take over a day. The battery is then discharged and recharged. After forming, the battery acid is typically dumped, the battery refilled, and the charge topped off. 

Dry formed plates are removed from the electrolyte tank, dried, and assembled into the battery case. Dry formed batteries are shipped dry, i.e., without electrolyte solution in the battery.

After formation, the battery is given a high-rate discharge test to rule out any defects. The battery may also go through several more discharge/recharge evolutions to achieve optimum operation. After receiving the finishing charge, the battery is sent for final assembly and shipment. 

What Equipment is Used in the Battery Formation Process?

There are a variety of ways in which equipment can be employed during battery formation. The process can be manually performed, or, carried out with automated equipment, or some combination thereof. Because of the time and steps involved, formation is universally the bottleneck in battery production.

Improving efficiency in formation can have positive effects on other areas on the production line. The best way to accomplish this is utilizing equipment rather than personnel. Automated battery formation equipment has enormous advantages over manual methods in terms of time savings and throughput. 

The increase in throughputis not at the expense of quality. To the contrary, automated equipment has been demonstrated to deliver higher quality results with greater consistency than manual methods. Additionally, and most importantly, automated methods expose employees to fewer safety and health risk factors versus their manual counterparts.

In the case of wet lead-acid battery formation, the first step is filling the battery case with sulfuric acid solution. Done manually, the worker fills each battery with a filling device. Or a machine can automatically fill each battery with a precise amount of electrolyte every time. The automated machine is faster, more accurate, wastes less, and never goes on break. Using a filling machine also greatly reduces employee exposure to sulfuric acid. From this health and safety aspect alone, automated battery-filling machines are worth the investment. 

During wet formation, batteries are usually submerged in a water bath to control heat. Manually manipulating the batteries into and out of the water-cooling system is slow and labor intensive. Controlling the water temperature manually can also be problematic. Automated water bath equipment maintains the water bath at the desired temperature and level while allowing automatic loading and unloading.

Automating the water bath step is enormously quicker. It makes for a higher quality battery because the water temperature is automatically controlled. It also requires fewer employees because it eliminates so many manual steps. With manual manipulation of the batteries being greatly reduced, the opportunity for on-the-job injuries is similarly reduced.

During the actual charging or forming process, controlling the charge with software-driven automatic charging equipment has been demonstrated to be far more effective than manually controlling the power supply. In that study, formed plates were compared where the power supply was manually controlled for one sample and controlled via automated software-controlled equipment for the other.

The results were conclusive. First, plates that were formed in an automated fashion were visually apparent to be of higher quality. Second, subsequent x-ray analysis and power tests verified there was a distinct difference in the quality of the two batteries with the automated sample being clearly superior.

After forming, the batteries must be tested to ensure there are no defects. During this step, the battery discharges a high rate of current for a short period of time. The high-rate discharge test is a quality assurance electrical load test conducted to verify the battery’s performance. 

The decision to automate this function is easy when you consider that an automated machine can test up to eight batteries a minute. There is no way to match this with human personnel. If the tester senses a defective battery, it automatically sends it to a reject station.

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Lead-acid battery formation is a very critical step in the battery manufacturing process. It can be performed by different methods, but the end result is a fully charged and tested battery ready for shipment. With all the steps and criticality of the battery formation process, the fastest, most precise, and safest method to form lead-acid batteries is with the use of automated equipment.