Adding Regen to DC? Not for range...

8012 Views 29 Replies 12 Participants Last post by Overlander23, Jul 7, 2010

ewdysar

Discussion Starter · Jun 30, 2010

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?

Thanks,
Eric

1 - 20 of 30 Posts

JRP3

· #2 · Jun 30, 2010

Seems like a rewound alternator, or DC generator head, are about the only options. You could also stack an AC motor on top of the DC motor for extra power and built in regen, if it ran the same voltage, expensive though.

TX_Dj

· #3 · Jun 30, 2010

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.

ewdysar

Discussion Starter · #4 · Jun 30, 2010

So let's say I chose the rewound alternator solution. Are there ones available on the market or do I have to wind my own? Since it appears that the "high power" alternators' voltage varies with RPM, is there an off-the-shelf controller that can take the raw alternator output with fluctuating voltage and output my desired 168V? Are perm magnet alternators the only way to get to our kinds of voltages? If so, adding a clutch like Wayne's S-10 configuration seems mandatory.

Adding an A/C drive does sound like a way to get the best of both worlds, but cost was one of the factors pushing me towards D/C. I guess that if they were coordinated correctly, both motors could be smaller... Hmmm.... Still seems expensive....

ewdysar

Discussion Starter · #5 · Jun 30, 2010

TX_Dj said:
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.

Yeah, I can see that weight is coming back into play. I beginning to think that your last paragraph may be what we're stuck with until better A/C systems become available.

Back in the mid 1990's while I worked for Disney, a friend won Frank Wells' electric Fiero in a rideshare drawing. I helped him refresh the car and worked on a number of other EV's. At that time, I decided that for me, the FLA batteries were too big of a performance/range hit for how I expect a car to work. Fast forward to today, and I'm converting my 30' sailboat to electric with a 48V system and a TS 160Ah battery pack. With a battery pack that weighs less than half as much, a conversion is looking more viable.

AC Propulsion was building some solid systems back in the 1990's, I would have figured that they would be more available by now. Oh well....

Eric

DavidDymaxion

· #6 · Jul 1, 2010

You could get a sepex DC motor and sepex controller http://www.kellycontroller.com/kdc1260324v-120v600aseparate-excited-with-regen-p-418.html . I have no personal experience with Kelly, so that is not a recommendation for or against them.

I'm doing a diy controller for my sepex motor -- regen down hills is very nice. Strong regens seem to have the side benefit of keeping the batteries balanced.

ewdysar said:
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?

Thanks,
Eric

ewdysar

Discussion Starter · #7 · Jul 1, 2010

DavidDymaxion said:
You could get a sepex DC motor and sepex controller http://www.kellycontroller.com/kdc1260324v-120v600aseparate-excited-with-regen-p-418.html . I have no personal experience with Kelly, so that is not a recommendation for or against them.

I'm doing a diy controller for my sepex motor -- regen down hills is very nice. Strong regens seem to have the side benefit of keeping the batteries balanced.

So where can I find Sepex motors? Is there a system available that is of similar performance to a WarP9 with a 750A controller? All I can find is the D&D 6.7" that seems max out around 84V, or Kostov's, where the only high voltage model is the 268mm model. Are there Sepex controllers available that run to 144-156V?

Thanks,
Eric

JRP3

· #8 · Jul 1, 2010

ewdysar said:
Are there Sepex controllers available that run to 144-156V?

Thanks,
Eric

Not that I've ever heard of. Saying "get a sepex" sounds good, until you actually try to do it.

toddshotrods

· #9 · Jul 1, 2010 (Edited)

JRP3 said:
Not that I've ever heard of. Saying "get a sepex" sounds good, until you actually try to do it.

Then it's frustrating as h3!!.

Since I finally realized that high-power SepEx wasn't worth the hassle, I've been testing not using the engine for braking in my (5spd) Accord daily driver. It's really not that big of a deal once you get used to it. Definitely not something that's worth spending a lot of unnecessary cash to simulate. You'd get more for your money with better brakes and/or more batteries.

DavidDymaxion

· #10 · Jul 1, 2010

I'm not aware of any current sepex controller that goes higher than the Kelly 120 V. I think the max Curtis one is 96 V.

If you want an off-the-shelf sepex solution, it looks like you have to either go lower power, or go multiple motors (might as well go AC in that case).

That's one of the reasons I'm doing my own controller!

ewdysar said:
So where can I find Sepex motors? Is there a system available that is of similar performance to a WarP9 with a 750A controller? All I can find is the D&D 6.7" that seems max out around 84V, or Kostov's, where the only high voltage model is the 268mm model. Are there Sepex controllers available that run to 144-156V?

Thanks,
Eric

Georgia Tech

· #11 · Jul 1, 2010

If you use a Sep ex motor, frorm what I have learned, MAKE SURE it has Interpoles!!!!

ewdysar

Discussion Starter · #12 · Jul 1, 2010

DavidDymaxion said:
I'm not aware of any current sepex controller that goes higher than the Kelly 120 V. I think the max Curtis one is 96 V.

If you want an off-the-shelf sepex solution, it looks like you have to either go lower power, or go multiple motors (might as well go AC in that case).

That's one of the reasons I'm doing my own controller!

Ok, so what sepex motor are your running?

Eric

Georgia Tech

· #13 · Jul 1, 2010

ewdysar said:
Ok, so what sepex motor are your running?

Eric

I am not running ANY motor at the moment... I have a BIG sep Ex motor just sitting in my Garage.

I have read some SERIOUS debates and posts on here on the importance of interpoles for High voltage Sep Ex systems... It seems the consincous is that a Sep Ex system with out interpoles can be run at about 72 volts max...

ewdysar

Discussion Starter · #14 · Jul 1, 2010

Georgia Tech said:
I am not running ANY motor at the moment... I have a BIG sep Ex motor just sitting in my Garage.

I have read some SERIOUS debates and posts on here on the importance of interpoles for High voltage Sep Ex systems... It seems the consincous is that a Sep Ex system with out interpoles can be run at about 72 volts max...

What kind of "BIG sep Ex motor"? Like I said ealier, the only Sep Ex motor specs that I've seen rated to 144V is the Kostov 268mm. I'm just trying to figure out what options actually exist...

Eric

DavidDymaxion

· #15 · Jul 1, 2010

I have an old Kostov 11 inch sepex. It does have interpoles. I have only run it gently so far, but by the end of the summer I should have some higher voltage and current results to report.

ewdysar said:
Ok, so what sepex motor are your running?

Eric

Tesseract

· #16 · Jul 1, 2010

The Kostov SepEx motor looks to be an excellent size even for relatively heavy conversions. Too bad making a SepEx controller that can work with a variety of motors is such a P.I.T.A. ...

As for a really "Big" SepEx motor... how about this 13" GE monster which is going to be added to our dyno real soon:

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ewdysar

Discussion Starter · #17 · Jul 1, 2010

Tesseract said:
The Kostov SepEx motor looks to be an excellent size even for relatively heavy conversions. Too bad making a SepEx controller that can work with a variety of motors is such a P.I.T.A. ...

As for a really "Big" SepEx motor... how about this 13" GE monster which is going to be added to our dyno real soon:

Cool, though I might have to beef up the suspension in the Metro...

Eric

Georgia Tech

· #18 · Jul 6, 2010

ewdysar said:
What kind of "BIG sep Ex motor"? Like I said ealier, the only Sep Ex motor specs that I've seen rated to 144V is the Kostov 268mm. I'm just trying to figure out what options actually exist...

Eric

It's one that I bought from a guy on this forum 10" motor ...I just don't have time to fool with it...It has an inverted spline shaft that I don't know what to do with. I have an 11 inch series, just out of the machine shop and a monster 13 inch like Tesseract's 13 inch except mine is the series version, his is the sepex version..

I sure wish I could figure a way to retro fit Interpoles in one of these things.....

G

· #19 · Jul 6, 2010

So a decent little sepex with interpoles and a medium weight vehicle and a kelly sepex 120 volt controller and you have a system. What's so bad about that? Sure it's not a super high voltage system but what is interesting is that if you ask Kelly Controller your needs I am sure they can build you one for higher voltage. Did you ask them? They are actually very willing to work with you. I have a software modified SepEx controller we are now going to be able to test. I am sure they will build a 144 or 156 volt controller that will power a SepEx but if you go that high of voltage you risk flashover. Advance it and you loose regen ability to the point you may damage the com even with sepex. So a nice small car like a VW should do just fine with 120 volts and regen with a decent sized 9" GE SepEx motor. You can change parameters to your controller to custom configure the software to work better with your motor. It is still possible. You can control the amount of regen too. 0 to full on. I will let you all know about our testing. Got the pan and going to mount the motor and do some tests.

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david85

· #20 · Jul 6, 2010

ewdysar said:
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?

Thanks,
Eric

Just a suggestion, but have you considered dropping your system low enough to run a sepex or AC motor like JRP3? His Fiero has fully functioning regen setup and seems to have enough pow - well, I'll let him tell you how it runs

I do agree however that under some conditions, not having any engine brakes can be hazardous.

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