Using Horn Button to activate Regen Braking

[Bedmountain]

Hello All

I am currently trying to put my first e-bike build together using a rear MPIII. I have a bike with hydraulic disc brakes which I would like to keep.
I have read many posts regarding using the horn button to cut the motor and start regen.
Unfortunately I haven't found a post that explains this in enough details for me to do it.
Is there anybody out there that can help me out and explain exactly which wires I need to connect up?

Really appreciate any help anyone can provide...

[e-lmer]

The horn button is just a pair of wires just like the brake lever switches.
You just have to connect the pair that is 'horn' on the switch to the
pair that is 'brake' on the controller (instead of the brake levers.)

If you have more questions, photos of your setup will help us give details.

[Bedmountain]

Thanks for the reply - really appreciate the help...

You have certainly cleared up the wiring route for me.

At the moment the wires all have nice neat and waterproof (I think) plugs on them.

To plug the horn wires into the brake connectors am I right in saying I would have to cut the plug off of the horn/cruise control button cable (and separate the 4 wires into horn pair and cc pair) and cut the plug off one of my brake cables and try and attach that to the horn pair so that it will fit into one of the brake sockets (1 or 4)? [See Pic]

Although I am quite capable of soldering wires together and heat shrinking joins etc I'm a bit reluctant to start hacking up what looks like a really neat cable set up with all the wires going into the 4 way controller plug.

Any advice on the best way to go about this? Are the plugs fairly easy to open up and seal again on the MP3? (Just realised I hadn't specified MP III and looking at some pictures of MP2's it looks like this would have been much easier on that version?)

Sorry - just one more question... Does it matter which of the 2 horn wires goes to which of the 2 controller wires (are they color coded?) - thanks

[e-lmer]

I would have to cut the plug off of the horn/cruise control button cable (and separate the 4 wires into horn pair and cc pair) and cut the plug off one of my brake cables and try and attach that

Kind of.  I suggest using an exacto knife and just splitting open the covering for the switches.
You would not be using the brake levers, so you could cut them off with no problem.

You could easily patch the brake wire into the exposed horn button wires with minimal impact,
then heat shrink the whole shebang.

[Bedmountain]

Thanks e-lmer

Does it matter which way round I connect the pair of horn wires to the pair of brake wires coming from the controller e.g I could connect horn[1] to brake[1] or brake[2]?

Or does it not matter as I'm just making a loop that is cut off when the horn button is pressed.

Sorry for the newbie questions. I don't understand how the regen works. Is regen automatically switched on when the motor is cut off or does the brake switch kill the motor AND turn on regen mode?

[e-lmer]

My understanding is that the wiring harness has one ground that is shared between all of the
accessories, so yes it matters.

Refer to this diagram:
http://www.goldenmotor.com/e-Bike-DIY/MP3%20SmartPie%20Wiring%20Layout.jpg

The brake and horn and light switch all share a common ground signal.

[Bedmountain]

Thanks e-lmer

I am nearly there – please bear with me for just a little longer - I appreciate your patience!...

I plan to amend the wiring harness as listed below – is this right?:

Socket 4 (brakes) – not used

Socket 3 (throttle/lights) – Use Plug3 as it is out of the box

Socket 2 (Cruise/Horn) – Take Plug2 apart and leave cruise signal, ground wire and battery+ going to their respective pins in Plug2. Separate the Horn wire and solder it to the brake signal pin of Plug1 (that I have removed from the brake cable)

Socket 1 – Use the newly created Horn plug that only has the horn wire connected to the pin that is going into the Brake Signal hole (no ground?)


Do I need to worry about the horn[+/-]/light[+/-] wire that comes out from the bottom of the wiring harness?

[Bikemad]

Do not try to open up the plug assembly on the end of the wire as you will more than likely ruin it completely.

You can either carefully cut into the middle section of the cable instead to reveal the four inner wires ready for cutting, insulating and splicing, or it might be neater to run the brake wire direct to the switch (assuming the cable is long enough to reach) and then make all the connections inside the switch housing as described here:













The switch I dismantled was from an early Magic Pie, so the colours of the wires may be different to yours.

The two existing wires going to the horn switch must both be safely insulated as one of them is connected directly to battery +.

If you prefer to splice the wires in the centre of the cable, the two cut ends of the wires still connected to the switch need to be connected to the two wires in the brake connector cable and it doesn't matter which way round they are connected. If you can stagger the two joins by having slightly different length wires it should make a neater job of the whole joint when either insulation tape or heat-shrink tubing is applied afterwards.

I hope the pictures make it a bit clearer for you.

Elmer,
Although the horn and light units both share a common ground connection, there is no actual ground connection on either the horn or the light switches themselves as they only switch the battery supply to the lights and horn.

Alan
 

[Bedmountain]

Bikemad - I'm staggered by the amount of effort you have gone to to explain this to me! It's very much appreciated.

I was able to attach the brake cable into the horn switch as per your info. It seemed to go pretty well - just need to make some final battery connections before I can test it.

I'll let you know how I get on.

Thanks again,
Ben

[Bikemad]

Thanks for the appreciation Ben.

I always find it much easier to understand things by studying pictures instead of just reading a page of text, so I try to use the same approach when I have to explain more complicated details to others.

I have a naturally curious mind and I have always enjoyed taking things apart to see what's inside to understand how things work.
I seem to be getting much better at this than I used to be as I can now reassemble most things that I've completely dismantled without having any bits left over at the end.

I also find that taking photos is essential on more complex items as my memory is nowhere near as good as it used to be.

Anyway, I'm sure you won't be the only person to benefit from the post.

Alan
 

[Bedmountain]

Hi Alan

Had a quick test last night and the horn/cutoff/regen setup is working a treat...

Motor is cutting out regularly (works again when battery switched on and off). I think this might be down to either the thickness of the cables coming from the battery as they are much thinner than the ones supplied with the MP3 or the dodgy soldering I have done between the CA shunt and the controller....

Anyway that's another topic!

Thanks again for all your help (you too e-lmer)

[Bikemad]

Thin wires can result in a considerable voltage drop across their length that could easily cause the controller's Low Voltage Cut-off to activate.

The wires can also get very hot and even melt under high current loads if they are much too thin. 

Thicker wiring is far more efficient, so it would be beneficial (and also safer) to upgrade any wires that are not really capable of carrying the required current.

Alan
 

[Gregor]

Big thanks from me too Alan. I am waiting on my MP3 being delivered from Gary in Canada. That was going to be my first ask as I want to keep my hydraulic brakes too. making people happy that you don't even know about.   Cheers.   Gregor.