# Regenerative Braking in Sevcon Gen 4 80/350



## nospin1234 (Aug 28, 2016)

I have an Lipo4 24 kw go kart project underway and I am using the 80/350
Gen 4 with a Motenergy ME1012. I have the drive system 100% operational, 
and after driving a Tesla model P100D I want to incorporate an automatic 
regenerative system like the Tesla.
It has a two level system, that can be set on the control panel for high 
And low level regenerative braking. When you let off the peddle there is
A point where you are coasting, then as you release the peddle completely
The regenerative kicks in at the level you have selected. This system makes
Most routine braking unnecessary!
Any ideas?


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## frodus (Apr 12, 2008)

I'm not sure the question, but I'll comment.

The Sevcon (And Curtis AC controllers) have what we call neutral braking. This is off throttle regen, that acts like engine braking when you let off the throttle. This allows you to coast, or allow more regen the more you let off.

They also have Braking regen. This can be on/off or a variable input (like another throttle) that controls how much additional regenerative braking you want. This can be set so high that it actually locks up the rotor at max regen (dangerous IMHO). You can use a 0-5V output pressure sensor on your brake lines to sense how hard you're pushing to kick in some extra braking from your mechanical brakes.

I WOULD NOT depend on electrical braking alone, in case something fails or the contactor opens, you cannot stop.

Hope this helps.


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## nospin1234 (Aug 28, 2016)

Thanks Travis

I definitely want neutral braking and I have a second Curtis pb6
I could use for regenerative braking linked up to the brake peddle


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## rdoig (Nov 7, 2012)

Hi Travis, I am also using a SEVCON GEN4 80v size 4 controller and the regen is working but I find it is a bit crude for a daily drive car. I am controlling it with a pot on the dashboard, trying to assess how it will work if I connect a pot to the brake pedal.

I have found that it seems to be a bit sensitive in part of the pot range and insensitive at the low end. In other words, when I start turning the pot on there is very little braking until about 1/4 turn then it comes on very quickly to 80 Amp and the braking is too severe. When I back off the pot it seems to lose braking even more quickly. This would be very hard to control with a brake pedal.

My question is, have you managed to find a way to refine the regen braking so it can be controlled by the initial movement of the brake pedal, before the mechanical brakes start biting?

All the best
Robert


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## goingbush (Jun 20, 2017)

rdoig said:


> Hi Travis, I am also using a SEVCON GEN4 80v size 4 controller and the regen is working but I find it is a bit crude for a daily drive car. I am controlling it with a pot on the dashboard, trying to assess how it will work if I connect a pot to the brake pedal.
> 
> I have found that it seems to be a bit sensitive in part of the pot range and insensitive at the low end. In other words, when I start turning the pot on there is very little braking until about 1/4 turn then it comes on very quickly to 80 Amp and the braking is too severe. When I back off the pot it seems to lose braking even more quickly. This would be very hard to control with a brake pedal.
> 
> ...


I have done this on My LandRover 

I have set the stop light switch to come on before the friction brakes start to engage, The stop switch activates regen , amount can be adjusted in programming , or adjusted by 5k pot on dashboard,

Also can engage by pulling on red knob as a 'hill descent' also adjusted on the pot. The sensetivity of the pot can be adjusted in programming (with Curtis )


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## goingbush (Jun 20, 2017)

Youtube dash cam clip .
Testing the Regen braking mod. Not much of a hill but the only one in battery range . The braking from 60 was regenerative only (red knob only not foot brake) . The descent control was on max then i decreased regen level with dash potentiometer & then max again. Works well , this was 3rd gear high range.

https://youtu.be/8Dy28Fg28bg


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## frodus (Apr 12, 2008)

rdoig said:


> Hi Travis, I am also using a SEVCON GEN4 80v size 4 controller and the regen is working but I find it is a bit crude for a daily drive car. I am controlling it with a pot on the dashboard, trying to assess how it will work if I connect a pot to the brake pedal.
> 
> I have found that it seems to be a bit sensitive in part of the pot range and insensitive at the low end. In other words, when I start turning the pot on there is very little braking until about 1/4 turn then it comes on very quickly to 80 Amp and the braking is too severe. When I back off the pot it seems to lose braking even more quickly. This would be very hard to control with a brake pedal.
> 
> ...


Have you tuned the range of the voltage on the pot? What voltage output on the wiper are you measuring (max and min)?

It needs to be set up, it may not work out of the box. If you have IXXAT cable and DVT, I can set up a gotomeeting and help (consulting charges apply).


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## rdoig (Nov 7, 2012)

Thanks Travis, unfortunately I don't have the interface you mention. If I manage to find one cheap I will take up your offer.


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## rdoig (Nov 7, 2012)

Thanks for that. Some good ideas there which I will use. I really need to know if the SEVCON is capable of more refined braking. Has anyone out there managed to tame it?
Cheers
Robert


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## frodus (Apr 12, 2008)

rdoig said:


> Thanks for that. Some good ideas there which I will use. I really need to know if the SEVCON is capable of more refined braking. Has anyone out there managed to tame it?
> Cheers
> Robert


You can definitely tune the braking. There's both neutral braking and braking regen. Both are adjustable.

I can show you on the one I have here if you want to see what is possible. Then decide if you want to get the IXXAT and DVT.


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## Toolcraft (12 mo ago)

frodus said:


> I'm not sure the question, but I'll comment.
> 
> The Sevcon (And Curtis AC controllers) have what we call neutral braking. This is off throttle regen, that acts like engine braking when you let off the throttle. This allows you to coast, or allow more regen the more you let off.
> 
> ...


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## Toolcraft (12 mo ago)

I have some doubt with regen braking, i am using flywheel to keep the motor on for sometime, whereas i am cutting of the battery supply. Do you reckon that the controller will be still on with AC current coming from the motor?


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## Toolcraft (12 mo ago)

frodus said:


> I'm not sure the question, but I'll comment.
> 
> The Sevcon (And Curtis AC controllers) have what we call neutral braking. This is off throttle regen, that acts like engine braking when you let off the throttle. This allows you to coast, or allow more regen the more you let off.
> 
> ...


I have some doubt with regen braking, i am using flywheel to keep the motor on for sometime, whereas i am cutting of the battery supply. Do you reckon that the controller will be still on with AC current coming from the motor?


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