mogur said:
I usually charge to 80 percent and have a moderately steep 1,000 foot downhill run from my house in the morning. By the time I get to the freeway where it flattens out, I have usually regen enough to be down to only 1 circle of available regen capacity...
rainnw said:
Also, note that the regen circles do not have smaller circles in them. These will appear as you drain the battery. If you are going down a hill, i have actually had these regen intercircles slowly go away...must be making some electricity!
This morning I charged an extra 40 min at L2, on top of 80% charge done last night, giving me 11 bars. I have seen warnings in other threads to avoid frequently "toping off" the "tank," but I interpret this to mean battery
reversals (charge-discharge-charge) near the top are bad. Adding more charge to the charge done over-night is OK as long as the car is not driven between charges. Two charge periods interrupted by a pause is no different than one continuous charge period.
This principle, that battery reversals are bad near the top of SOC, is why the smaller Prius battery, being frequently charged and discharged at 8C or more, is kept to a small range near the center of its capacity. Since the Leaf usually operates within +- 1.5C, it can operate over a much larger fraction of its total capacity, but it still should be limited near the very top of its SOC.
After the charge the display showed double regen circles for all but the left-most circle.
After driving 4.0 actual miles, I dropped to 10 full bars, at which point I got the last double-circle, indicating maximum available regen. Is this about when other folks get to maximum regen ?
Next I drove down a short but moderately steep slope in ECO and 2 circles of regen seemed adequate with no friction braking. These tests indicate to me that if I arrange things so that I get back to a maximum of 11 bars on a long decline, I will still have some regen braking. Is this consistent with other people's experience, or is 11 bars too high? Is this number different pre and post the firmware update ?
In order to estimate how much room you need to leave for regen before beginning a long descent, my first thought was to just compute
PE = A*1.3*.85, where:
A = altitude change in 1K feet,
PE = potential energy in KWhrs,
1.3 is the weight factor for the Leaf,
.85 is the efficiency factor I am assuming for the regen itself.
However, for most roads this would over-estimate the allowance needed. There are 3 categories of descent: In the first, a road with an incline of 2-3% seems enough to keep the car rolling at 15-30 mph at the power-neutral circle. If the road allowed 30-45 mph, an incline of perhaps 4% could keep the car steady. Under these ideal conditions there is no regen and no regen loss, just 100% conversion of potential energy into motion dissipated by rolling resistance and aerodynamic drag. No charging allowance would be needed for this category.
For steeper inclines, category 2, some regen (with its efficiency loss) would be needed, and the formula above would apply. Roads with even more incline, category 3, would require some friction braking (100% loss) (probably at tight turns on switch-backs), which would consume additional potential energy that would not be put back into the battery. To arrive at an accurate estimate, one needs to estimate how much of the road is of each type.
