# Hpevs ac76 regen ...



## dougingraham (Jul 26, 2011)

You can add a pressure transducer to your mechanical brake system and allow that to add in progressive regen. It is said to work very well and feels quite natural and doesn't require an additional control.


----------



## frodus (Apr 12, 2008)

There's two types of Regen with the Curtis. 

Neutral braking when you take your foot off. 

And a brake input Regen. 

Both have an independent maximum that can be set in software. Usually you set neutral to a fairly low number and it acts like engine braking. The brake input would be more like your brakes.


----------



## crackerjackz (Jun 26, 2009)

Has anyone used a hand controlled 0 to 5 k pot to control braking or no ? ... Should i add another pedal left of the clutch ?


----------



## frodus (Apr 12, 2008)

Hook it to the brakes.


----------



## crackerjackz (Jun 26, 2009)

What happens if you slam the brakes ? What happens if you pres 25% on brakes regen is 25% but you lode regen because the brakes also brake no ?


----------



## evmetro (Apr 9, 2012)

crackerjackz said:


> Has anyone used a hand controlled 0 to 5 k pot to control braking or no ? ...


I think you are on to something good here. I am planning a shifter mounted regen trigger that I can just squeeze with my finger tips when I want regen. I am probably alone in my concern about disturbing kinetic energy with regen that kicks in when it is not needed or wanted, but I am going this direction. I want to drive an EV that only has regen when I want it. In emergencies, I would not have time to reach for the shifter to trigger a regen control, but the regular brakes would do just fine. On wet or icy roads, I would not have to worry about regen disturbing my traction. When traveling down long grades or pulling up to red lights, I could leisurely reach for my shifter and regen to a stop with a the variable regen trigger.


----------



## crackerjackz (Jun 26, 2009)

evmetro said:


> I think you are on to something good here. I am planning a shifter mounted regen trigger that I can just squeeze with my finger tips when I want regen. I am probably alone in my concern about disturbing kinetic energy with regen that kicks in when it is not needed or wanted, but I am going this direction. I want to drive an EV that only has regen when I want it. In emergencies, I would not have time to reach for the shifter to trigger a regen control, but the regular brakes would do just fine. On wet or icy roads, I would not have to worry about regen disturbing my traction. When traveling down long grades or pulling up to red lights, I could leisurely reach for my shifter and regen to a stop with a the variable regen trigger.




Im thinking the same reason for using a hand controlled pot ... Id probrebly add a on off switch in series though in case someone doesnt know what there doing i could just shut it off ... 

Im trying to find someone who would have tested it .... Anyone lol ??


----------



## grip911 (Dec 14, 2011)

I use it on my car to cut or engage regen when I`m racing. I only engage the regen on the main motor to slow me down on the track at the end of the run. Saves the brakes.


----------



## crackerjackz (Jun 26, 2009)

grip911 said:


> I use it on my car to cut or engage regen when I`m racing. I only engage the regen on the main motor to slow me down on the track at the end of the run. Saves the brakes.



You use a hand controlled pot ? Or transducer style ?


----------



## grip911 (Dec 14, 2011)

Right now, it is just the clutch wire option on the 1238-7601 that I use with an on-off switch mounted on the tunnel near the emergency brake. I haven`t tried the potentiometer trick yet, but that should be easy enough to do with the signal usually used with the transducer.


----------



## major (Apr 4, 2008)

crackerjackz said:


> What happens if you slam the brakes ? What happens if you pres 25% on brakes regen is 25% but you lode regen because the brakes also brake no ?


I talk about this in this thread: http://www.diyelectriccar.com/forums/showthread.php?t=26847&highlight=regeneration Especially post #6 but also posts #2, 11, and 26.

The Curtis runs in torque control so there is a blend of braking from the motor and from the friction brakes. It works great. Put your sensor on the brake pedal where it belongs (IMO)


----------



## crackerjackz (Jun 26, 2009)

major said:


> I talk about this in this thread: http://www.diyelectriccar.com/forums/showthread.php?t=26847&highlight=regeneration Especially post #6 but also posts #2, 11, and 26.
> 
> The Curtis runs in torque control so there is a blend of braking from the motor and from the friction brakes. It works great. Put your sensor on the brake pedal where it belongs (IMO)




So your for the transducer type braking system ?


----------



## major (Apr 4, 2008)

crackerjackz said:


> So your for the transducer type braking system ?


The one I've used most often is the PB-6 (potentiometer) although I have seen pressure and even a force transducer used.


----------



## crackerjackz (Jun 26, 2009)

Thanks everyone for your input ... Im gonna try some sort of transducer . But id like to find a way of modifying with a potentiometre or other the effectivemess of the regen or i should say sensibility of the transducer .. Has this already been done ? Or am i starting from scratch ?


----------



## major (Apr 4, 2008)

crackerjackz said:


> Thanks everyone for your input ... Im gonna try some sort of transducer . But id like to find a way of modifying with a potentiometre or other the effectivemess of the regen or i should say sensibility of the transducer .. Has this already been done ? Or am i starting from scratch ?





major said:


> I talk about this in this thread: http://www.diyelectriccar.com/forums/showthread.php?t=26847&highlight=regeneration Especially post #6


From that referenced post #6.


major said:


> I also have used an adjustment pot on the dash so that the driver can fine tune the amount of regen, or turn it off if it proves uncomfortable for the driving conditions.


----------



## Caps18 (Jun 8, 2008)

evmetro said:


> I think you are on to something good here. I am planning a shifter mounted regen trigger that I can just squeeze with my finger tips when I want regen. I am probably alone in my concern about disturbing kinetic energy with regen that kicks in when it is not needed or wanted, but I am going this direction. I want to drive an EV that only has regen when I want it. In emergencies, I would not have time to reach for the shifter to trigger a regen control, but the regular brakes would do just fine. On wet or icy roads, I would not have to worry about regen disturbing my traction. When traveling down long grades or pulling up to red lights, I could leisurely reach for my shifter and regen to a stop with a the variable regen trigger.


http://www.youtube.com/watch?v=JXBxpQHPRnI&list=PLONsyQ0cLqNEpRYNgZtbQbrxASEjK2U3l&feature=share

Check out what the new plug-in Cadillac ELR has. (It is close to the end of the commercial).

I'm going to wait to deal with modifying the regen until after I have the whole thing working. The default of no energy pedal = regen seems ok to me. That is kind of how my ICE car works now. No gas pedal = slows down.

Now, I would love to see the Mythbusters test the hypermiling techniques of EVs. Would coasting be better than regen. Does it matter in the city? What about on deserted country roads? Hills? Stop and go traffic?


----------



## evmetro (Apr 9, 2012)

The back of the steering wheel looks like a good spot, and it looks like they are seeing what I am seeing. Regen is great, but only if used appropriately.


----------



## crackerjackz (Jun 26, 2009)

Hummmmm ... I like there idea but font need the heavy onboard generator though ...


----------



## Caps18 (Jun 8, 2008)

I've had my mind changed and now I will figure out how to attach this brake pressure transducer to the brake system in order to only regen when the brake pedal is depressed.


----------



## evmetro (Apr 9, 2012)

Caps18 said:


> I've had my mind changed and now I will figure out how to attach this brake pressure transducer to the brake system in order to only regen when the brake pedal is depressed.


Here is an interesting thing to read before committing to a regen configuration

http://jackrickard.blogspot.com/2010/07/more-regenerative-braking-results-it.html


----------



## Caps18 (Jun 8, 2008)

The big production cars are setup to coast, but have regen and brake lights that come on when you hit the brakes.

It depends on your driving style, but the theory is that coasting and then regen at the very end is better than having to constantly push the energy pedal and then try and regen a lot when coming to a stop.


----------



## Caps18 (Jun 8, 2008)

evmetro said:


> The back of the steering wheel looks like a good spot, and it looks like they are seeing what I am seeing. Regen is great, but only if used appropriately.


Has anybody in the DIY community done the steering wheel regen button idea? I was driving yesterday in my ICE car and was thinking which would be the best. Hitting the brake pedal would probably activate the regular brakes. Having a switch you could push on the steering wheel would work out great for the driving around town that I do. I do need to be able to coast quite often too.

And i'm not sure there is a range of regen intensity when using the 0-5V or 0-5 ohm methods, but the third option in the controller wiring manual is for a switch that will activate the brake lights either when the real brakes are pushed or when the regen switch is hit.


----------



## Ivansgarage (Sep 3, 2011)

Caps18 said:


> Has anybody in the DIY community done the steering wheel regen button idea? I was driving yesterday in my ICE car and was thinking which would be the best. Hitting the brake pedal would probably activate the regular brakes. Having a switch you could push on the steering wheel would work out great for the driving around town that I do. I do need to be able to coast quite often too.
> 
> And i'm not sure there is a range of regen intensity when using the 0-5V or 0-5 ohm methods, but the third option in the controller wiring manual is for a switch that will activate the brake lights either when the real brakes are pushed or when the regen switch is hit.


Check out this post...

http://www.diyelectriccar.com/forums/showpost.php?p=383967&postcount=15


Ivan


----------



## Caps18 (Jun 8, 2008)

It is probably a lot easier hooking that up too compared with adding a brake transducer into the brake line someplace.

I could probably add a bigger paddle onto that thumb throttle to make it easier to hit with your fingers. Kind of like the high beam or turn signals on the steering column.


----------



## tomofreno (Mar 3, 2009)

evmetro said:


> Here is an interesting thing to read before committing to a regen configuration
> 
> http://jackrickard.blogspot.com/2010/07/more-regenerative-braking-results-it.html


And this:
http://www.diyelectriccar.com/forums/showpost.php?p=192152&postcount=559

And this:
http://www.diyelectriccar.com/forums/showpost.php?p=192247&postcount=562

Jack's tests made no sense. I'm fairly confident he had a touchy throttle and kept lifting it too much resulting in too much slowing with regen, then accelerating back to speed, etc, modulating the kinetic energy of the car, and loosing a bit of energy each cycle. 

My present thinking is there are a number of ways to implement control of regen, pot on the throttle, accelerator only, brake pedal (pot or transducer), or a combination of the last two (the way HPEVS does it). All can be used effectively, but I think the combination HPEVS uses might work best. You can then apply aggressive regen with the brake pedal, and have it less aggressive on the accelerator. But if you like a lever on the steering column go for it. To each his own.


----------



## dougingraham (Jul 26, 2011)

Jack did more regen testing in a later program. He had other people drive the course and got different results. I believe that Jack was the most efficient driver and his most efficient result was no regen. Brian was the least efficient driver and he gained the most energy recovery from regen. But it was a poor result compared to Jack's driving without regen.

To me there must be some benefit to it. If the only thing you do is apply regen when you are actually applying the brakes you will reclaim some energy. People who hypermile almost never touch the brakes. Coast down regen is probably at best a minor loss of efficiency. It just happens to make the car feel more like an ICE car to drive. I don't have regen on my car. And I cringe a little every time I step on the brakes because of this. But overall it has probably made me a more efficient driver.


----------



## Moltenmetal (Mar 20, 2014)

How about this: a little extension of the brake pedal travel, and an added pot on that travel, so you gradually apply regen when you press the brake pedal and are at full regen before you apply any mechanical braking? The pressure transducer on the brake system wastes energy you could recover by regen so isn't appealing. The 1pedal driving default loses the benefit of coasting which could be a fairly big efficiency hit. The thumb throttle brake could work but would take a fair bit of driver attention. Only question is, does the master cylinder rely on the brakeedal springs to pull it back when not in use? If so, the extra brake pedal throw would be hard to accomplish.


----------



## major (Apr 4, 2008)

Moltenmetal said:


> How about this: a little extension of the brake pedal travel, and an added pot on that travel, so you gradually apply regen when you press the brake pedal and are at full regen before you apply any mechanical braking?


I've done the little pedal on top of the big pedal and then found it isn't necessary. From a thread previously referenced in this thread. 



major said:


> I usually put the pot on the brake pedal. The first 1/2 to 1 inch of pedal depression activates the pot and then the hydraulics start to work as you depress the pedal further. Most brake pedals have enough free play to do this.


And the same thing with the pressure transducer. When you get it calibrated it will activate full regen before any significant pressure on the service brakes so there is no friction.


----------



## tomofreno (Mar 3, 2009)

Moltenmetal said:


> How about this: a little extension of the brake pedal travel, and an added pot on that travel, so you gradually apply regen when you press the brake pedal and are at full regen before you apply any mechanical braking? ...


 Like this?

http://www.diyelectriccar.com/forums/showpost.php?p=259540&postcount=6


----------



## tomofreno (Mar 3, 2009)

Moltenmetal said:


> ... The 1pedal driving default loses the benefit of coasting which could be a fairly big efficiency hit...


 How do you figure? I have regen on the accelerator pedal and have no problem coasting (current = 0). Seems to be a common miss-perception that if you have regen you don't coast. If I see a traffic light change far ahead I ease off a bit on the throttle and then ease off more to coast when I get close enough that I think I can coast close to the light without holding up traffic, then lift off the throttle when I get close to apply regen to stop. Somehow, Jack has convinced many that is less efficient than coasting then applying mechanical brakes. 

To get maximum energy back through regen though I should remain at the speed limit until I get close to the light then aggressively apply regen to stop, as McRat and Duncan pointed out in another thread on regen in the wiki. Whether that results in the least overall energy use in the approach to the light I don't know. Doubt it, since I imagine the work done continuing at constant speed further toward the light is greater than the extra energy regained through aggressive regen from the higher speed. Either way, the difference isn't much energy.


----------



## major (Apr 4, 2008)

tomofreno said:


> To get maximum energy back through regen though I should remain at the speed limit until I get close to the light then aggressively apply regen to stop, as McRat and Duncan pointed out in another thread on regen in the wiki. Whether that results in the least overall energy use in the approach to the light I don't know.


No, it won't be the least used energy, but the most productive within the limits of the law and the least energy for that case (opposed to using friction brakes). In other words, it is a trade off; energy for time  This becomes a big factor for commercial applications like route delivery or trash collection where the time is money.


----------



## Moltenmetal (Mar 20, 2014)

Exactly. Something like that is what I plan to do in my own conversion. Wasn't planning on the 2nd pedal, but rather just using the "slop" in the first bit of travel of the brake pedal as major has done.

Cheaper than the transducer on the brake hydraulics, and less likely to waste energy. More akin to what my Prius C does, although it's all done in software. They give a helpful little indicator of regen braking on the display- when you go over-scale on the display you're applying the friction brakes. Watching that dial and anticipating stops saves a lot of gas in the Prius.

Keeping regen currents down increases the amount of energy you actually stuff back into the batteries during a particular deceleration.


----------



## GuySmily (May 11, 2012)

Just curious.. How powerful is max regen, anyway? Is it anywhere near as strong as max acceleration? Is it so powerful that you barely need mechanical brakes anymore?

In my 02 Honda Insight, the puny 10kw electric motor is still enough to make a noticeable difference in required braking force. This is especially obvious when you run over a bump or pothole and the over-sensitive ABS kicks in and shuts off your regen, which feels similar to someone snipping your brake line.. (Not a high point in the car's design)

Anyway, I have about 1.2 miles of continuous downhill roads where the insight picks up speed despite being at maximum regen. I'm curious if the ac76 regen is strong enough to help me maintain speed or even come to a stop at the bottom.

I'd also like to know if there are any risks involved with too much regen. Obviously you don't want to charge past 100%, but is there a risk of supplying too much current? What about overheating the batteries? In my insight, regen cuts off about 2/3 of the way down the hill because of battery temperature.

Also, in relation to the discussion above... The insight does not have continuously variable regen. We have 3 states:
No regen at any throttle > 0%
30% regen at 0% throttle (coasting)
100% regen at any level of braking (tied to brake light sensor).
I'm assuming this would be quite harsh in an EV, but at least it doesn't require any additional sensors. OTOH, if regen is weak and sucky in the ac76 then maybe it won't even matter.


----------



## onegreenev (May 18, 2012)

I believe the regen is plenty powerful enough to stop your vehicle quite quickly if you set the parameters high enough. 

As for the other posts below about coasting and throttle regen, I frankly would like to have my throttle provide very little regen and my brake provide the most. I have to fiddle with the throttle to get into a coasting like mode in the Leaf then off completely to get better regen then on with the brake to get even more. Its not so easy to just find that sweet spot of neutral regen on the throttle when your not really thinking about it and paying attention to traffic. As I drive I'd much rather just get off my throttle and coast until I NEED regen then apply the brakes. I can set my parameters by selecting power or eco and I get stronger regen in eco mode than in power mode. 

A tiny bit of regen on the throttle makes the car feel like a regular ICE but its not an ICE and I don't want ICE. I want electric. 

Now if I my Leaf was a manual then the throttle regen is no issue because I can just push in the clutch to disengage and coast that way if I chose to do so. So all of you with manual transmissions I think maybe should have the Regen on the throttle and brake inputs. Still gives the option to coast if you desire. 

I truly don't find myself coasting much even in my ICE between stops. Its kind of a moot thing and just a personal preference. So choose what you LIKE. 

Pete


----------



## Moltenmetal (Mar 20, 2014)

The AC50/Curtis arrangement that I'm leaning toward is 600A max acceleration and 200 A max regen, if the Gage's are to be believed.

My Prius has 190,000 km on it and the brakes are barely worn. Previous cars I've used for this commute were through the front pads in 120,000 km or so. The Prius C I bough in September has a regen intensity indication on the display which is quite helpful in maximizing energy recovery. Brake feel in both vehicles is totally seamless- you can't really tell when the mech brakes are beginning to be applied.


----------



## crackerjackz (Jun 26, 2009)

Really confused know in what option i should choose lol ... Ill decide when doing the actual wiring i guess lol ill leave spares in case of change


----------



## mizlplix (May 1, 2011)

I use a 0-5 pot mounted to the under side of my steering column to regen with hand pressure.

It is set strong enough to stop the car without using any hydraulic brake at all. 

I still have my 4 wheel brakes for panic stops too.

The regen will lock and skid the rear tires if I apply them too aggressively.

I have the curve set up slow at first and the last 50% lever is aggressive. It gives me a proportionate feel.

I do not like mine hooked to the foot pedal because if you get into a marginal traction situation as an errant landscape sprinkler head, it tries to spin the car. (As my first set up was done)

This way I have perfect control.

I do a regen stop at about 1:50 in this video. I use NO foot brake...






Miz


----------

