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[evtricity]

I recently set up a custom regen lever on a Zero SR using a ZX14 clutch lever joined to a pressure transducer and wired into the footbrake function of the Zero's Sevcon controller (see photo at the end of this post).

The result has been a very smooth and powerful regenerative brake which can push high currents of over 140A or 15kW back into the battery. The regen brake can lock the back wheel at speeds under 50kph on dry roads matching the performance of the stock rear brake with much better feel than a foot brake.

How does this compare to the regen you can get using the Zero's Eco, Sport and Custom modes?

As you all know, the 3 performance modes each offer different levels of regen for neutral throttle and for when you first start pulling on the front brake lever ("an on/off style brake switch"). To more accurately assess the regen available in each mode you can use the amps and kWatts figures provided by the Zero phone app (or Sevcon controller software) -  see photo at the end of this post.

To give you an idea of the relative regen power, here are the stock settings for the maximum possible in Custom mode (according to the Sevcon controller). These are for a 2014 Zero SR, and they might be a little different for your year/model.

- Max battery charge rate = 40A
- Custom regen % on neutral throttle = 10% (shown as 100% in the Zero app)
- Custom regen % on (front) brake switch = 10% (shown as 100% in the Zero app)

For comparison, a separate regen lever would allow you to increase the maximum regen substantially. To achieve the power described above the following settings have been applied:
- Max battery charge rate = 150A
- Regen % on neutral throttle = 0%
- Regen % on (front) brake switch = 0%
- Regen % on footbrake = 60%
- Removed the max regen limit of 4,500rpm (which is 75% of your max motor speed of 6,000 rpm and normally means that regen doesn't work above 120kph/75mph on SR, S and DS models).

For those looking at setting up a separate regen lever, changes need to be made in the Sevcon controller and Main Bike Board. Here are the details:
- In the MBB, the maximum regen limit should be increased (from 4500rpm) to the maximum motor rpm - usually 6000rpm.
- In the Sevcon the maximum battery charge current can be increased from 40A to 91A.
- To go higher than 91A, in the Sevcon controller the RPDO 1 setting which controls the Maximum Charge limit can be removed and in its place a dummy (16-bit) entry placed. The maximum battery charge current can now be increased beyond 91A (the MBB limit).
- In the Sevcon under Torque Control there is a braking torque limit of 72Nm. You shouldn't need to adjust the limit as 60% (used above) of that limit is plenty of power.
- There is also a brake feathering option in the Sevcon which reduces the available regen at lower speeds (to prevent the rear wheel going into reverse). To have regen bring the bike to a foot down stop, setting the feather start to 1000rpm (about 27kph) and ending at 0rpm with an ending regen torque of 0Nm works well. A higher feather start rpm may be better if you use strong regen.
- Lastly, you need to determine whether you want the throttle or regen lever to take priority when both are pulled. I like the throttle to take priority but like most settings here there is no right or wrong, it's what you like best for your riding.

For wet riding, lower torque settings are more appropriate and can be readily set using the three Sevcon profiles (modes) in a similar manner to what you can achieve with the Zero app in custom mode.

For road riding - this high power, well modulated brake allows you to balance front and rear brakes better and even has an in-built mechanism to safely handle rear wheel locks (not as good as ABS but keeps any wheel locks very brief). The only downside I have found with this regen setup is that on the track where you're either on the throttle or on the brakes, it doesn't give the motor any respite and results in higher motor temperatures. In normal street riding this wouldn't be an issue for everything but the most spirited canyon riding.

For anyone who may be interested in adding a regen lever to their bike a friend of mine is selling the levers that offer a similar set up to mine @ http://www.diyelectriccar.com/forums/showthread.php/regen-levers-pressure-transducer-138066.html
 
Of course, you'll still need to wire the cable from the lever into the Sevcon and make the changes in the Sevcon controller via an IXXAT CAN-USB adapter.

Based on some of the feedback for 2016 models, having a left hand regen lever would be a good aftermarket option that could be readily added to any Zero. Include a parameter in the Zero app to control its regen/braking force and I think there could be quite a few takers for this upgrade.

Interested to hear your thoughts and any questions on regen braking for your Zero.
- Is a left hand hand brake the best way to implement  regen brake?
- Is this something Zero should be considering as standard or optional for future bikes?
- What about a bidirectional throttle like in the Vectrix scooters?

[Richard230]

Personally, I would prefer the bi-directional Vectrix-type throttle for that modification.  Since I ride four IC motorcycles in addition to my Zero, and am always switching back and forth, I can see how having a clutch lever that performs the regen function would be a problem for me.  But having the regen triggered by either the brakes or a reverse throttle would eliminate that potential issue when switching from the Zero to other IC motorcycles, in my opinion.  Right now I used the Zero app to apply 100% regen when braking.  I wouldn't mind having 150% when applying the front brake and 100% when using the rear brake lever.

[Burton]

What was the max Nm you got with stock 40amp limit? I think mine is currently set up at 10Nm at torque setting and 20% at brake regen setting. I need to raise it up a bit though as well as the max rpm. At this setting I haven't peaked 25Nm when regen was maxed out like I could stock so I think the numbers do different things with the "analog foot brake lever" setting vs stock. (7.2Nm and 15% was stock on my bike when I got it)

I have the same setup as dgh853 and like it so far. Being a ex gammer I have no problem with switching between a clutch and regen lever on bikes.

[protomech]

The left lever could be made to approximate the action of a clutch, if you so desired.

1. Significantly improve "off-throttle" regen as described here, though not to the point of locking the rear wheel. Care would need to be taken in wet or low-grip riding conditions, perhaps by using eco switch as a "rain mode".
2. When the left lever is pulled, attenuate the regen strength (optionally, also reduce torque when the throttle is rolled on). When the lever is pulled completely the bike will freewheel, as if the clutch on a gas bike was disengaged.

I suspect the way you have it setup is better if you only ride electric, but it may cause you to build bad muscle memory if you occasionally ride gas.

[kingcharles]

The Vectrix throttle also avoids that regen and accelerate can be applied simultaneously.
And it worked as a slow speed reverse too, but your regen brake could probably do that as well if you wanted.

I am surprised that no other bike uses the Vectrix throttle yet. The Vectrix IP was not sold at the chapter 7 auction so I guess the patented feature is now freely available?

Everyone who has ever ridden a Vectrix and I talked to was super positive on the throttle.

[Richard230]

The Vectrix throttle also avoids that regen and accelerate can be applied simultaneously.
And it worked as a slow speed reverse too, but your regen brake could probably do that as well if you wanted.

I am surprised that no other bike uses the Vectrix throttle yet. The Vectrix IP was not sold at the chapter 7 auction so I guess the patented feature is now freely available?

Everyone who has ever ridden a Vectrix and I talked to was super positive on the throttle.

Including me when I went for a test ride at Marin BMW (now the headquarters of Planet Box, where my daughter works - its a small world) about two years after Vectrix was introduced to the U.S. market.  I think Vectrix was one of a number of factors that put Marin (CA) BMW on the rocks and left the county with no BMW motorcycle dealers in sight.     But the Triumph/Ducati dealer in San Rafael still seems to be doing well.

[oobflyer]

"I think Vectrix was one of a number of factors that put Marin (CA) BMW on the rocks and left the county with no BMW motorcycle dealers in sight"

Curious why that would be... That's where I got my Vectrix in 2008 (17,000 miles and still running strong). At that time gas was nearly $5/gal. and the Vectrix was selling "like hotcakes" according to the salesman.

They got $10K from me and I told everyone I knew to go there and buy an electric bike :-)

As far as the Vectrix-style throttle-controlled regen braking - I agree it's the best way to go - it's intuitive and natural- would love to see Zero try it.

[Richard230]

Marin BMW was put under by poor management.  Taking on Vectrix was just one more nail in their coffin.  The Vectrix scooters sold well for a short time and then sales died, for whatever reason.  But that was just a small part of the business.  There were much larger factors, including personal and financial issues.

[Francois]

well done bravo

[Nuts n Volts]

Getting ready to install my regen lever. I understand that my signal needs go into pin 23 of the sevcon and just ground to B-,  but where are you getting power. 10V off of pin 34 where the throttle takes its power?

Thanks
Kyle




Sent from my iPhone using Tapatalk

[evtricity]

Yes, you need to split off from the 10/12v throttle input. I used a DC to DC converter to get the voltage to the 5v I needed for my pressure transducer.

[evtricity]

There is a small resistor in the throttle line which you can remove and splice in it at that point (as it was only needed for the XU model).

[Burton]

I tapped into the 24vdc powering the CAN requiring external power supply

Pin 28 (yellow red stripe on 2013 models)

Routed that into the 5v powersupply

There are some things technically wrong in here as this wasn't intended for my electric motorcycle savvy friends but people who knew nothing that were interested to know what I was doing so I didn't QC this.

[Nuts n Volts]

Thanks for the tips guys.  I was worried about pulling too much current from the throttle line. 

Note that I do not have a Zero.  I just have a ZF75-7 motor and size6 controller on my bike. 

I am going to go ahead and just try running 10V through my pressure transducer and tuning that signal on DVT software.  I'll tie into the 10V out at the Sevcon.   I think that should work ok.  If not I'll get a small DC/DC converter

[Burton]

Make sure your pressure transducer can support 10v.

The one I got only supports 5v, any thing over it will fry it and then you will have to bleed your brakes again >_<

I actually had to do my pressure transducer twice as I messed up the mounting pins the first time and had to get the 90 degree elbow for the second attempt.

It doesn't matter where you pull the voltage from your sevcon as long as it meets your needs. it does however have to come from the sevcon and not the dc/dc onbike converter.
If you are not using pin 28 I know the pins required for that connector if you wanted to just run a pin from there to your dc/dc converter in the future.