A technical working group is developing a white paper to demonstrate testing standards and how 12V lead auxiliary batteries fulfil functional safety requirements in EVs. Andrew Draper reports.
The Safety State-of-Function (SSOF) working group held its annual workshop after the eighth Automotive Lead Battery Advancements (ALBA) workshop in Colombes, France, from 11–13 June. It was run jointly with the Consortium for Battery Innovation (CBI), European Committee for Electrotechnical Standardisation (CENELEC) and with technical oversight from Eckhard Karden.
Karden, formerly Ford’s technical R&D expert, is a driving force behind the work, according to CBI. He is now a consultant for the association.
Over 90 technical experts from the lead battery and automotive industries attended and joined break-out sessions on different topics.
Alistair Davidson, CBI’s executive director, told BEST: “Basically it’s an automotive meeting to discuss the future of 12V batteries, specifically for automotive applications.” He said the meeting has adapted as the automotive market has changed, but remains focused on the opportunities and research areas for different automotive applications for lead batteries, particularly future opportunities in low voltage EV batteries.
Car companies including Audi, Ford and Stellantis attended and shared their ideas on technical requirements for 12V auxiliary lead batteries.
Begüm Bozkaya, CBI technical manager, told BEST: “Within the SSOF working group, our aim is actually to document some verification methods of battery diagnostics to be able to be sure that lead batteries are still used in future vehicles.
“And the white paper will contain SSOF proof-of-concept studies to show battery diagnostics in order to determine the safety features of lead batteries, which is at the moment missing.”
The white paper is work-in-progress and should be ready for next year’s meeting, she said. Not all EV manufacturers have experience of 12V lead batteries in EV applications so this paper will be useful for them in understanding the role of the auxiliary lead battery, according to Davidson.
Bozkaya said standardisation of auxiliary batteries was a focal point, with reports from an IEC standardisation group. “They are working at the moment with a new test methodology for the auxiliary battery function of lead batteries. So this time, for such functions we are looking at, for example, charge recovery, pulse power characterisation, that kind of specific tests which are different to the micro hybrid applications of lead batteries.”
In the micro hybrids, the focus was dynamic charge acceptance (DCA) but it has now shifted to charge recovery for auxiliary applications. “Within this standardisation group, they have already a draft version of this charge recovery test, for example. And what they reported at ALBA is that they will have this new test standard at the beginning of next year.”
She said there is a need for more understanding of new functions and how lead batteries can adapt.
Longer charge steps
“It’ll be longer charge steps in cars for auxiliary batteries. So that’s why we also have the name difference of charge recovery rather than the DCA. So currently, within our CBI research programme, we are focusing on, for example, the knowledge that we have from the DCA function – how additive formulations can improve the DCA, and we are looking at whether those kinds of formulations in a similar way can also improve the charge recovery. We are currently in the understanding phase.”
Charge recovery is a new parameter to test the performance of lead batteries in auxiliary-related charging regimes. The focus is to determine charge capacity on a longer time scale in comparison to short pulse evaluations in DCA.
The group’s work will be dealt with at the automotive session of CBI’s European Lead Battery Conference in September.
