With an unprecedented demand for energy storage, reducing the energy used in battery manufacture is a significant first step towards the global goal of carbon reduction.
For the last four years UK Powertech (UKP) and its partners, have been warning the lead-acid battery industry of the drawbacks of bad formation connections. Mostly the result of high resistance connector terminal joints, caused by either insulating corrosion layers or low contact area due to malformed battery terminals, the effect on production, quality and profit margins is very damaging. The list is surprising:
- Energy losses and excess heat
- Arcing leads to connector and battery damage, and in some cases, fires
- Increased water loss through higher battery temperatures causing lower hydrogen overvoltage
- Active material quality degradation due to higher process temperatures
- Longer formation times where programmes are temperature limited
- Financial losses amounting to hundreds of thousands of USD
It has been five years since the team identified the connection problems that were associated with modern formation production methods and equipment. Rectifier and cooling equipment has progressed to the extent that formation times for some battery types have been reduced from 24 to 8 hours. The unwelcome side effect is that charging currents for some types, by necessity, have tripled.
Unfortunately, standard inter-battery connectors used in the industry have not changed for many decades, and what did an adequate job 10-15 years ago, is now one of the causes of cell damage, high scrap rates, and poor product quality. Incredibly, LAB manufacturers have remained oblivious to the energy inefficiency and financial losses resulting from high resistance formation connections.
After four years of R&D and field trials by UKP and partners, the causes and extent of the problem were identified. It was found that a barrier layer of lead sulphate on the internal surface of old, used connector heads created a high connection resistance, resulting in energy losses of 3-5%. Resistance-generated heat caused higher battery temperatures and extended process times, giving lower productivity.
Field trials showed that badly fitted connectors, due to operator error and persistent battery terminal manufacturing flaws, created electrical arcing that caused internal pitting corrosion of the connector head, and ultimately, department fires. These problems combined were shown to be costing lead-acid battery manufacturers many hundreds of thousands of USD per annum.
However, the good news is that effective solutions to these problems were devised and tested by the same participating companies. These consisted of proper maintenance, cleaning of used connectors to prevent or minimise the build-up of a high resistance corrosion layer, and a new connector with a split head (TSC design), to incorporate battery terminal imperfections. The benefits, resulting from low resistance interface connections and better connector/terminal contact area, include:
- Virtual elimination of spark damage and fire risk
- Substantial energy savings of 3-4%
- Lower battery temperatures give a higher CCA performance due to AM structure
- Shorter formation times in temperature limited programmes enabling up to 10% higher productivity in some instances
- Reduced water loss due to lower battery temperatures creating a higher hydrogen overvoltage
- Less battery repair work resulting in more efficient, lower-cost production
These benefits give verified, substantial savings of hundreds of thousands of USD by reducing energy and scrappage costs. Yet achieving this was not difficult. Proper connector design, coupled with high manufacturing standards and simple in-service connector maintenance procedures, can substantially improve a battery manufacturer’s profitability. UKP is the only connector supplier on the globe to have conducted such an in-depth study, followed up by more than a year of field trials with major battery manufacturers. By the end of last year, the importance of this work had been validated by the participating companies’ uptake of our new and standard connector products, to the extent that UKP’s annual turnover increased by more than 50%.
The team is now turning its attention to the formation process itself. So far, the energy-saving from the laboratory trials has exceeded 12%. The processing time has also been slashed (in one manufacturer’s process), from 10h:38m to 8h:14m. Laboratory work continues, but this year UKP will be rolling out field trials to establish the transition from the laboratory to the factory shop floor.
UK Powertech is at the forefront of improving lead-acid battery manufacturing, helping to obtain lower cost, improved reliability, and a lower carbon footprint, for the world’s lead-acid battery manufacturers.
For a more in-depth look at lead battery formation click below