Author Topic: 3kw Non-hub Moped Conversion help  (Read 28729 times)

Offline Bikemad

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Re: 3kw Non-hub Moped Conversion help
« Reply #75 on: July 01, 2020, 09:46:08 PM »
You cannot use the low level "3V" brake signal wire to power your brake lights, but it should be possible to wire a 12V relay along with a couple of diodes into the Blue wire to allow the 12V from your DC/DC converter to power the brake light bulb through the relay:



If you are using the original light fitting with a 12V 21W/5W stop/tail light bulb (or a lower wattage LED equivalent) it might be better to rewire the brake light switches so that they switch the 12V supply from your DC/DC converter directly to the brake light bulb and the Brake (High Level) wire on the controller:



In this configuration, the low level brake wires are no longer used and should be left disconnected as shown.

With most motorbike conversions where the 12V lighting system is retained, the original foot and hand brake switches would be utilised by simply connecting the High Level brake signal wire to the switched side of the brake switches as per the above diagram.

Alan
 

Offline Knightgreider

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Re: 3kw Non-hub Moped Conversion help
« Reply #76 on: July 03, 2020, 03:26:58 PM »
Wow! Thanks, Alan!

I'm going to go with the first option since I already have the relay. I will just need to change the wiring. Would this diode work for this application?
https://ebay.us/kKlvB1

Thanks again!

Offline Bikemad

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Re: 3kw Non-hub Moped Conversion help
« Reply #77 on: July 03, 2020, 08:16:19 PM »
3A is probably overkill but they should work fine.

I would have used a couple of 1N4002 (1A 100V) diodes as the highest load would be the 150~200 mA (0.1~0.2A) passing through the relay windings.

Alan
 

Offline Knightgreider

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Re: 3kw Non-hub Moped Conversion help
« Reply #78 on: July 03, 2020, 08:41:58 PM »
Gotcha, I ordered one! I'll update you when I install it.

Thanks Alan!

Offline Bikemad

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Re: 3kw Non-hub Moped Conversion help
« Reply #79 on: July 03, 2020, 08:48:13 PM »
I hope you ordered more than just "one", as you need two;D

Alan
 

Offline Knightgreider

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Re: 3kw Non-hub Moped Conversion help
« Reply #80 on: July 10, 2020, 05:10:11 PM »
Yup I bought 10 of them. This is my first experience with diodes that don't emit light haha. Anyway, since a diode prevents the electrons from traveling in a certain direction, would you wire up the diodes in the way you posted?

I have looked at a few websites for help on diodes and I know a lot more about direction, but even when I use the multimeter, I'm not sure which side of the brake cable I add the diode to since I have already spliced both cables to go to the relay before. Am I wiring it up for a forward bias or a reverse bias? A forward Bias right?

I will post pics when I have it wired up.

Thanks for your help with this!

Offline Bikemad

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Re: 3kw Non-hub Moped Conversion help
« Reply #81 on: July 10, 2020, 07:36:48 PM »
Yup I bought 10 of them. This is my first experience with diodes that don't emit light haha. Anyway, since a diode prevents the electrons from traveling in a certain direction, would you wire up the diodes in the way you posted?

Yes, they should definitely be orientated exactly as shown in the following diagram:


Click on diagram to enlarge it.

Diode A allows the brake signal voltage to travel to ground via either of the brake switches when either switch contacts are closed (brakes applied), but also prevents the 12V passing through the relay windings from making its way up the brake signal wire and back into the controller when the brake switch contacts are both open (brakes not applied).

I'm not sure which side of the brake cable I add the diode to since I have already spliced both cables to go to the relay before. Am I wiring it up for a forward bias or a reverse bias? A forward Bias right?
The Black and Blue brake switch wires can be connected either way around as the mechanical brake switches are not polarity sensitive and will allow current flow in either direction. Just make sure that diode A connects to the brake signal wire from the controller and not the Black ground wire and it must be orientated as shown.  ;)

Diode B allows current to flow through the relay windings to ground (activating the relay) when either of the brake switches are closed, but its main purpose is to prevent the regen from permanently engaging in the unlikely event of the DC/DC converter suddenly failing, as it will prevent a dead DC/DC converter from effectively grounding out the brake signal wire when the output of the DC/DC converter is at 0V instead of 12V.  :o

Both diodes must allow forward bias and prevent reverse bias, as no current should be allowed to flow through either diode in the reverse direction.

Hopefully this has clarified the intended purpose of the two diodes.



Alan
 

Offline Knightgreider

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Re: 3kw Non-hub Moped Conversion help
« Reply #82 on: July 11, 2020, 04:09:12 PM »
Alan thank you! It works beautifully.

https://drive.google.com/file/d/1mxZdOxm9xkjq5LPmSDoJ_Ws3WR7QaDam/view?usp=sharing

I 3d printed a relay and flasher holder next to the DC to DC converter.

Thanks again for all of your help!