[cbrenthus]

Yes, it is normal. Our vans have an intelligent battery sensor that is constantly measuring the batteries and charging as needed. When the batteries need to be charged, the voltage goes up to 14.4v or so, and when it senses they are charged it drops way down, I've seen 12.9v with the engine on before. Its not like older cars like my '02 trans am where the voltage is a solid 14.4v when running. I think the purpose of the new smart system is to increase fuel mileage and reduce overcharging of the battery.

I don't know why decelerating increases the voltage, but I wouldn't be surprised if it is programmed that way to top off the battery anticipating using the brakes, and ESS event, or even idling.

What kind of symptoms are you having that got you started on looking into the battery voltage?