AGM batteries, like most lead-acid batteries, typically come with multiyear warranties that provide for free replacement if the battery fails in the first three years, and then offers a prorated replacement schedule for the rest of the warranty period. "AGM batteries are designed for the kinds of loads" placed on them by stop-start systems, says Garth Cole, executive director of product development for Johnson Controls' Original Equipment business unit.įord expects - and warranties - the stop-start Fusion's AGM batteries to perform throughout their three-year life expectancy, says Birgit Sorgenfrei, Ford's stop-start systems program manager. But Milwaukee-based Johnson Controls, which has been selling its AGM batteries for use in automakers' stop-start systems in Europe since 2008, says it has not experienced any increase in warranty claims due to premature battery failures. Some critics claim that the demands of stop-start systems can quickly degrade AGM batteries. Those are essential characteristics for a battery that's being called on to start and restart a vehicle's engine scores of times a day. It also is pressurized for a greater power density.ĪGM batteries' advantage over conventional 12-volt lead-acid batteries is that they recharge up to five times faster and can be deeply discharged with no damage. The electrolyte is contained in thin woven glass mats rather than flooding the cells as in a typical "wet" battery. Instead, they use a type of 12-volt battery called an absorbed glass mat (AGM) battery. But to keep costs down, conventional vehicles with stop-start systems don't use those powerful hybrid batteries. It's not a big problem in conventional hybrids because their batteries are huge compared to standard 12-volt lead-acid batteries. In addition to providing electrical power for climate control systems, the battery in a vehicle equipped with a stop-start system also has to maintain audio and lighting each time the engine shuts down.
While a conventional car or truck might call on the battery for engine ignition and starter-motor power three or four times a day, a vehicle equipped with a stop-start system might place that kind of drain on the battery several dozen times a day.
Stop-start systems aren't terribly hard on the engines, but they do demand a lot of the vehicle batteries. Some stand-alone systems simply kick the engine back on whenever the cabin temperature falls above or below the driver's preset limits. After that, the system restarts the engine to keep the climate system working and cabin temperature comfortable.įord uses a similar system. In those cases, "you've got to do something," Poulos says.įull hybrid systems, such as Toyota's Prius, use an electric air-conditioning and heating system that isn't dependent on the car's internal combustion engine.įor its eAssist system, GM developed control logic that maintains cabin temperatures for up to 2 minutes when the engine is stopped. It's also an issue when there's a lengthy delay, such as at a railroad crossing or a major intersection with long intervals between red and green lights. It's not a huge problem on mild days or when the stop period is very short. "If you stop the engine, how do you keep the temperature in the cabin comfortable?"
GM models with the eAssist mild hybrid system include a stop-start system. "Heating and cooling is one of the big challenges in stop-start development," says Stephen Poulos, GM's chief engineer for eAssist and battery-electric propulsion systems. Most A/C systems also use power from the engine to run their compressors. That's because they draw lots of electricity from the generator, which doesn't generate with the engine off. Turn off the engine in your car or truck and both the air-conditioning and heating systems stop functioning.
0 kommentar(er)
