regen, doing it right

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regen, doing it right

fred ungewitter
My wife and I have been enjoying ownership of a Toyota Rav4EV for many moons. One of the accessories we added is a Palm PDA running software to read and display information from the OBDII connector, called Rav4Info. It provides vehicle computer information of the state of charge, pack voltage, current consumption and many other items.

The Rav4EV is factory-standard with two levels of regen, as well as the ability to disengage regen. There is a button on the shift lever (EB) which provides for a small level of "engine braking" regen. We leave that in the regen position at all times, and it is very easy to find the "neutral" point on the pedal. The level of regen is proportional as well. If one removes one's foot from the pedal, regen in EB is at max, but partial release provides a lower level of regen.

The other regen is on the shift lever (B) and is very strong braking/regen. We've found that we can engage it easily enough (think downshifting) when approaching an intersection which suddenly changes from green to yellow or red.

Having owned a Xebra (still do, up for sale), we have learned to be conservative EV operators, so coasting and gentle application of power is part of normal driving for us. Because every trip we make involves braking and stopping for traffic control devices, being in EB and using B to get some energy back, rather than burning it off in the brakes is the way it works for us. We do use long-distance observation and adjust speed as best as possible to catch lights changing to green.

On the statistical side of things, the Rav4Info display has shown us how well this works. The display provides a regen figure as well as a consumption figure. In one discharge cycle, approximately 60 miles, of which I was the primary driver, the vehicle consumed 208 watt-hours per mile if you disregard the regen. With regen in the picture, the figure was 167 watt-hours per mile. I'm a more conservative operator than my wife, so her numbers are slightly higher, but not even by ten percent more. It's almost completely flat here in this part of Florida and we rarely reach the speed limit on the roadways, but get close enough. My wife has told me that it's too easy to get too fast on the Rav4EV because it's so quiet, so powerful, and so comfortable to drive.

Toyota also incorporated creep into the drive train, which I find annoying. The Rav4Info display shows a higher energy consumption when stopped at a traffic light, so I push the stick into neutral and watch it drop to a level representing normal overhead (lights, pumps, etc). When the light changes, it's a simple matter to engage the drive position, less time than it takes to shift a manual transmission into gear.



Oh, yeah, there's one on eBay again, item 330433113746. In my opinion, it's going to be difficult to get a good price for a Rav4EV once the Leaf and others are real products, but the Rav4EV has held its value for a good reason. It's a great EV.


     
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