Is it best to ride the brake lightly on long downhills where you know you must slow down at the end as opposed to foot off the brake and gas and braking harder at the end? I ask because I "feel" that is must be easier to recharge the battery at smaller current levels than larger ones. Or is there some huge capacitor I don't know about that is helping this process? -Tim
Ideal, when you must stop at the bottom of the hill, is to do "60 Amp braking"...IOW it's been determined that maximal regeneration efficiency occurs when you regenerate at a rate of 60 amps. Now, unless you have a new ScanGuage with the hybrid data ability or a CAN-View you can't monitor that. Most of us feel that what you'd feel is moderate braking is the best. If you have to brake too hard at the end you run the risk of the regen braking kicking out completely...once you exceed a preset amount of brake pressure that will happen as the car reads it as an emergency braking situation. Speed is also a factor. If it's a slow hill...below 41mph specifically, then I'd brake lightly, but firmly enough to prevent the speed from exceeding 40mph...the point where the ICE would automatically kick in...until you need to begin 60amp braking to bring yourself gradually to a stop. If you're above 41mph anyway then i'd just let the speed build during coasting and begin braking at the point where a 60 amp braking would bring you to a stop where you need to stop.
I don't have a scan gauge so I brake as long as I need to, to bring the car to a stop at the bottom. If you use heavy braking then as Efusco said there is a danger of switching to friction brakes. A long slow deceleration will reduce heat losses due to electrical resistance in wiring and batteries. Also there is a better chance you won't have to stop if the reason you have to stop is a red traffic light you give it longer to change. If a hill is long enough the battery will reach full allowed charge and the HSD system spins the ICE over electrically to dump excess energy. If you can use this energy through the wheels to accelerate you save fuel.
