Advanced lead-carbon batteries could enable 48V super hybrid vehicles

November 19, 2014 // By Christoph Hammerschmidt
For hybrid electrical vehicles, they offer a new perspective of lower cost along with environmental benefits: Advanced lead-carbon batteries could help to avoid high-voltage batteries in HEVs, they can be fully recycled and they are more stable at low temperatures, says the European Advanced Lead-Acid Battery Consortium (EALABC). At the International Automotive 48 V Power Supply Systems conference that will take place next week in Düsseldorf (Germany), the group plans to highlight a technical paper describing these benefits.

Advanced lead-carbon batteries could attract the interest of carmakers since they enable them to introduce mild hybrid powertrains based on the new 48V supply network and thus at low additional cost, believes EALABC project coordinator Allan Cooper. "This will help them comply with stringent CO2 regulations being introduced in 2020 with even tougher rules following in 2025", he said. What's more, these batteries are made of materials that can be fully recycled into new batteries, enabling OEMs to further reduce their emissions. "This provides the most cost effective solution for 48V hybrids, which have a unique requirement for a battery demanding a high rate partial state-of-charge (HRPSoC) capability," Cooper explained.

Another advantage of advanced lead-carbon batteries: They can be charged at temperatures of minus 30 degree Celsius (-22°F) - a temperature range in which lithium-ion batteries already exhibit significantly lower performance than at normal temperatures. This temperature stability is essential for vehicles to be driven in the "snow-belt" countries in Europe, the northern part of the United States and Canada. Unlike their lithium-ion counterparts, advanced lead-carbon batteries do not require active cooling even at normal and high temperatures and no expensive battery management system.

“Future battery developments will most likely combine advanced lead-carbon electrochemistry with other types of battery design with for example bipolar technology, which will reduce the lead content by as much as 40 per cent, substantially reducing the size of a 1 kWh battery required for mild electrification of the powertrain,” says Cooper. “Meanwhile, advanced lead-carbon batteries, with their high levels of carbon in the negative active mass, already represent an exciting development that is truly state of the art, resulting in much improved battery performance ideally suited to 48V hybrids.”

The additional functionality of a 48 V hybrid vehicle fitted with a Belt Integrated Starter Generator (BISG), compared with simple 12 V stop-start systems, typically includes torque assist as well as kinetic energy recovery. This is