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Adding Regen to DC? Not for range...

8009 Views 29 Replies 12 Participants Last post by  Overlander23
I live in the foothills of SoCal and I notice that while I drive any of my ICE vehicles, auto or stick, I use downshifting to control my speed. I do this for traffic or hills. Since I am seriously considering a DC electric conversion, I would like some resistance from the drivetrain when operating under zero throttle. I would use the transmission to select the amount of drag, lower gears for more deceleration, just the same as the ICE vehicles. My intended pack voltage will probably be 156V (48 lithium cells). I know that a controller will be needed to prevent overcharging, the max regen (charging) voltage should be no higher than 168V - 170V.

Since I typically care about efficiency, I don't want to just drag the brakes all the way downhill or approaching a traffic signal (I don't do that today in my Suburban, Fit, Insight or 914-V8). So for the sake of driveability, how can I get the conversion to feel more like a regular car? I'm not impressed with the AC systems that are available today, none seem to match the power of a WarP9 for a similar weight.

I've spent a day reading way too many threads that barely touch on the subject (please don't mention perpetual motion) and the only practical advice that I mined from all that has been the guy with the S-10 that rewound his own alternator. I was hoping that I could buy most of the components necessary to build a similar finished product. I'm not looking for a kit, just some sources for the major components. I'm also open to alternative strategies. Anybody else headed down this path before?

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If you care more about the braking effect than the regen charging function, plug braking may be your answer. Also called dynamic braking, it's very similar in effect to regen, but instead of putting that energy back into the pack, you burn it off as heat in a resistor bank.

Not easily done with a series DC motor for the same reasons regen isn't easily done, so you'd still need some offboard generation device that can be "switch" into the mix to give you the braking effects. Then you're also carrying lots of extra weight to support that system, so your range goes down as well.

So long as your brakes can stay cool enough going down those hills so as not to fade and lose braking efficacy, I'd say just use the brakes unless you're willing to go all the way to build a proper regen system; otherwise it doesn't make sense to carry any additional weight to support the effect.
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