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Old 12-15-2015, 04:19 PM   #2 (permalink)
EcoModding Apprentice
Join Date: Feb 2015
Location: Sacramento
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Interesting read. Is this your paper, or a link to something that you liked? I have studied regen extensively via real world testing of EVs that I build, and have come to some simple but solid conclusions. What people like to focus on is the beautiful concept of capturing waste energy that is available in EVs, but they rarely look at one of the most important considerations, which is the proper management of kinetic energy. Just as wind turbines and alternators seem like great things to attach to a car for people who do not understand perpetual motion and thermal dynamics, off-throttle regen looks appealing to those who do not understand the conflict that it imposes on proper management of kinetic energy.

Braking regen is very effective, just as alternators and wind turbines can be if they are left behind when you drive away, but this regen needs to be utilized only when there is energy that is truly going to be wasted as heat from the friction brakes. If regen is deployed when the car should be staying in motion, then energy will be wasted. In the case of off-throttle regen, wasting energy is what happens. Off-throttle regen is a fantastic way to make an EV feel like an ICE, but everything that was changed to get get that ICE feel was an important part of how an EV can be so much more efficient. There is a distinct difference in how a DC sytem with no regen feels out on the road compared to how an ICE or EV with off-throttle regen feels, and this feeling is a vehicle that is not encumbered. If you program an AC sytem with regen to have no off-throttle regen, you can get this same thing.

Once you have an AC system that is programmed for no off-throttle regen, the next step is to set the car up with regen on demand, so that it can be used only when it is needed. Only the driver can choose when the best time to use regen is, since the road conditions are ever changing. In my most recent build, I have found an ergonomically correct location for my variable on demand regen system, and it is a potentiometer that is set up so that I can easily control ALL of the regen capability, not just the 10% to 15% that is typically available in off-throttle applications. This variable on demand regen system allows me to use regen to satisfy ALL of my braking needs. No blend with the friction brakes at all, although the original friction brake system is in tact and standing by as a redundant braking system. Regen can be a fantastic way to harvest waste energy, but the timing of when it is used is critical when efficiency is the goal.
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