How to connect a DC to DC converter?

[cwah]

Hello there,

I received today my 12V DC to DC converter:

Zenid e-Bike Parts

But I don't know how I could plug it to the bike?

Usually there is an input area and an output area, but here there is only an input??

Any idea how I can do that?

 

[NRG]

The black wire, ground or negative, will be common between input and output. That leaves the Yellow and Red, one for input one for output...the label states the red is the input and yellow the output...what is it you are trying to do?

 

[cwah]

I'd like to use my bike battery for my lights.

So I'd like to connect the converter between the battery and the controller.

If I connect the red and black wire to the battery, it would be a closed circuit. I'm wondering how I can have a "loop" between the battery, controller and dc/dc converter.

 

[NRG]

OK, its to power your lights....you need to take a feed from the battery, positive and negative to the converter. You cant insert the converter between the battery and controller. You have to T off the battery feed. When done, take the output yellow wire and wire it to your lights, connect to the positive. Take a feed from the black wire, connected to the converter, and connect to the negative on your lights.

Does that help?

 

[cwah]

I'm thinking about doing it like this:

Would that work?

 

[NRG]

Nearly, you have the two 12v lights wired in series so they will only 'see' 6v each, they may not light or not be very bright...otherwise its as I suggested.

 

[cwah]

Ok thanksssss

If I parallel the 2 light that should work then.

Going to try that now

 

[cwah]

I finally plugged in to my battery cable:

It seems to be working (but I only have around 8V output).

But the main problem is that with the converter plugged, I've lost 12V on my bike!! I went from 76V to 64V displayed on the cycle analyst.

I had a huge voltage lost. Is it normal? I thought the 10% loss would be on the light, not on the battery!! I hope I did something wrong because I don't want to loose that many volt for a converter (I'd rather puirchase a high voltage light)

 

[NRG]

You've not wired it correctly!, you need to tap into the battery wires as per your first Photo. What you have done is left the battery positive wire untouched and wired the converter in-line with the battery negative wire!

 

[NRG]

Wire it like this:

 

[banbury frank]

Hi cwah

with your Knowledge off electrics I would give members the information and diagrams before you connect them .Also have you never heard off fuses

This comment is meant in a friendly manner

Frank

 

[cwah]

Wire it like this:

Thanks for your incredible advice NRJ. Finally made that work
Will post picture once I plugged all the light

Frank, I finally added a 30Afuse to my cable

 

[benjy_a]

What light do you have? Not many 12v led bike lights around.

Sent from my GT-I9000 using Tapatalk 2

 

[cwah]

I'm just using hobbyking led strip for now:
HobbyKing R/C Hobby Store : Turnigy High Density R/C LED Flexible Strip-White (1mtr)

But I'm planning to use the standard 8.4V light (magicshine or other) to plug on my 12V DC-DC converter. There is a voltage difference but when a battery is fully charged the voltage is higher, probably around 10V.

So it won't be too different from a 12V source.


I've seen this light that seems quite powerful and cheaper than the magicshine MJ-808:
eBay | Inton 2x XM-L T6 2000 Lumen Road bike light

Maybe worth it, not sure yet.

 

[rog_london]

Hi cwah

with your Knowledge off electrics I would give members the information and diagrams before you connect them .Also have you never heard off fuses

This comment is meant in a friendly manner

Frank

Oh dear, here we go again - this is exactly the point I was trying to make in a previous thread when I was trying to put people off fiddling with things they had very little knowledge of...

I know it won't put them off - they won't get the message until they have set fire to the house or destroyed something either irreplaceable or expensive or both.

I'd certainly like to keep this friendly too - but as an engineer of many years experience who has been on the wrong end of something like this far too often I can only say that when it comes to electronics and power supplies with almost unlimited current capabilities (AKA lithium ion bike batteries) the golden rule has to be: if you don't fully understand what you're doing you need to remedy that deficiency FIRST and in any case before you dive in and start making connections.

Rog.

 

[cwah]

Yeah, I know. I don't have much knowledge in electronic but I'm learning. That's quite satisfactory to be able to achieve thing by myself

I now want to connect the light to my 3 speed switch:

The problem is that my actual 3 speed switch is already connected with my controller:

The ground and another cable are used in order to activate the regen on my bike.

Is there a way to use the same multi-speed switch for both the controller and the light? I suppose I'd need 2 different ground wire because it's different voltage?

 

[banbury frank]

Hi Ground is Ground all over the controller you can connect Regen but you then need a hi or low signal I don't know witch on your controller if you don't have brake switches you could use the green horn button

Frank

 

[cwah]

yes, but 1 ground cable will go through the controller. The voltage is 74 V.

And the other ground is from the DC converter at 12V.

So with 2 different ground, I'm not sure I can mix the wires (use the light and controller functions at the same time)

ps: Anyone know any cheap electric store in London? I only know Maplin but I think it's a bit expensive compared to what I find online.

 

[NRG]

cwah, ground is ground, 0v, you don't have 2 different ones...the converter 'ground' is the same as the controller 'ground' (ground is the wrong terminology but hey it it helps you understand) You need to switch the positive side of the lights separately from your three speed switch, so if the green button is a latch type and not used for anything else then wire to that...put it in series with the 12v feed from the converter to your lights...

 

[Synthman]

Yeah, I know. I don't have much knowledge in electronic but I'm learning. That's quite satisfactory to be able to achieve thing by myself

I now want to connect the light to my 3 speed switch:

Where did you obtain that switch from?

My bike has the exact one as that. The switch section snapped off from the handlebar clip but I glued it. The other thing is the indicator switch isn't waterproof at all. Last week I was on the way home and the indicator beeper wouldn't cancel at all until I got home and sprayed WD40 in it.