Brian Kesseler, Johnson Controls (jci.com) vice president and president of its Power Solutions business unit, which is responsible for the company’s battery business, believes that developments in other types of battery technology notwithstanding, lead-acid batteries will have a role to play under the hood of cars and trucks through 2030. Not that they’re going to be depending on the existing tech for lead-acid batteries, however: “The chemistry in lead acid batteries will change more in the next 10 years than in the last 100.”
That said, JCI is moving ahead with other types of batteries, like absorbent glass mat (AGM) batteries, which are finding particular use in stop-start systems because they recharge faster, cycle more, and last longer than conventional lead-acid batteries. The JCI AGM approach uses a microfiber glass fleece separator wrapped around the positive grid, separating it from the negative. Kesseler points out that in Europe, approximately 40% of the vehicles sold there are being equipped with start-stop systems, which can provide an 8% fuel-economy benefit. He says they’re projecting the market size for start-stop will be 80% by 2018.
According to Kesseler, the projection for the U.S. for start-stop market in 2018 is about half of the European penetration: 35 to 40%. And he suggests that the China market is ahead of the U.S. market.
The next development, a bridge between start-stop and full hybrids, is the microhybrid battery. This is a dual-voltage architecture approach, combining a 12-volt starter battery for the conventional starting, lighting and ignition (which is why these are sometimes referred to as “SLI batteries”) and a 48-volt lithium-ion battery for capturing the energy from regenerative braking and to handle heavier loads, such as air conditioning. The microhybrid can provide a fuel efficiency improvement up to 15%.
A challenge in the development of the 48-volt system, Kesseler says, was to reduce the overall size. He says that when they started testing on a BMW 3-Series, the batteries filled the trunk of the vehicle. Yet within a year, they reduced it to the size of a shoebox.
Kesseler says that one of the issues related to making battery technology more affordable is increasing the amount of component commonality. By making the parts the same, they are able to achieve better economies of scale, which helps drive down the cost. He also notes that rather than trying to provide batteries with a 10-year life, it would be better to work toward a 4-year-life 48-volt battery, which also means a less-expensive battery.
Consider: by having a lower-cost battery, there is a greater likelihood of more people buying the batteries, which means increased volume. If the batteries are common (the OEMs can tailor their approach via software controlling the powertrain system as a differentiator rather than having their own individual battery architectures), the cost is lowered through the commonality. Having a higher volume of common components means that costs can be reduced, which could lead to a proliferation of fuel-saving technology.—GSV