On Jul 24, 2014, at 8:31 PM, Ben Apollonio <e...@bapollo.com> wrote: > For your hybrid application, I'd go with the AC. One word: regen -- without > it to recharge the battery, "hybrid mode" is of little benefit; better to > just disengage the motor altogether.
I've been leaning towards AC since the beginning. I figure the biggest benefit from the electric motor will be with acceleration; if the electric motor does all that heavy lifting and then lets the V8 deal with cruising, that alone should be substantial. Along those lines, even if braking doesn't recover enough via regen to keep the batteries from emptying, an intelligent controller could apply minimal regen drag while cruising to provide just enough charge for accelerating from the next stop light -- and, again, only when the batteries are close to empty. And, with a *really* intelligent controller, I could punch in my expected trip distance, and it could adjust how much electric assist to give accordingly -- lots for shorter trips, less for longer ones. > However, running slow comes at the expense of the torque multiplication in > your gearing; ultimately, you'll be running the motor hot in a low-efficiency > region. That's what I'm gathering is the problem with direct drive -- not that the motors don't have enough power, but that they're not electromechanically efficient at low RPMs, and that translates into shorter range and more heat. Or, you *can* do direct drive with most any motor, but it's going to suck battery charge and lessen the motor's lifespan. And, conversely, dual motors work better in such situations because the load and head is spread between the two. Does efficiency go back up with dual motors, or is it just a matter of preventing overheating? > As for the hybrid mode, I would strongly encourage you to take it > incrementally, because the controls will be a challenge and you don't want to > be kept off the road while you figure it out. I think...that's an excellent suggestion. And the first hybrid mode can even be as simple as just turning on both systems at the same time. > The vacuum sounds like a good idea, but my gut says you'll need inputs from > the throttle too. You'll almost certainly require a control processor > (possibly Arduino, possibly more powerful). Collin has pointed me to GEVCU, an Arduino-based open source vehicle control project. I'm thinking the second hybrid mode is the same as above, but with GEVCU tapped into the lines and monitoring everything. Step three is to show what GEVCU thinks it would do with the throttle, and step four to actually wire it in so it can do its thing. > Since you're using the existing engine instead of an undersized one that > relies on the electric boost, and since your motor is fixed on the driveshaft > (meaning you can't regen without also burning energy in compression braking), > I think the fuel efficiency gains will be limited. I would say you should > think of it more like a Honda Civic hybrid than like a Chevy Volt/Prius, > except it will have the ability to fully disengage the engine for EV-only > drive. Actually, because of that fully electric mode, I'm expecting actual fuel economy to be superlative. The main battery options left on the table are 144V / 10 Ah / 10C, which perfectly match the AC-51's specs with a 14.4 kWh capacity. The back-of-the-envelope suggests that that should be in the range of 30 miles or so, which is going to cover most of my driving. And if I can get it so that the controller uses the whole battery over longer hybrid-mode trips, then, for example, a 60-mile trip would get at least twice the mileage with the system as without -- presumably, more than twice, because the electric motor would be doing its thing at times the V8 would otherwise be at its least efficient. All-day trips wouldn't see monumental efficiency gains, but I don't do very many of those. b& -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 801 bytes Desc: Message signed with OpenPGP using GPGMail URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20140728/1229f841/attachment.pgp> _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
