Wire verification with a DC-DC converter

[Milou]

Hi: I have a Chinese motorcycle scooter with a 48V DC to 12V DC Converter. There are three wires coming IN and OUT (Yellow, Black, Red). I traced each. Given their resources and output I am assuming as follows:

RED (Ignition, Instrument Panel, Controller) is the 48V input?
BLACK (Headlights, Horn, Instrument Panel, Controller, Kickstand [has safety switch], Battery) is the ground?
YELLOW (Headlights switch, 12V relay, Horn R switch, Horn L switch, Brake lever switch, Instrument Panel, Rear connector, Kickstand Switch) is the 12V output?

Would it be safe/easier to have the ground directly onto the frame with appropriate reference electrical source (battery) ground to the frame?

I would like to replace the DC to DC converter with a 12V xxxA battery of my own setup. I notice this not being the norm. Is there a logic/reason/safety issue with the separate setup (besides charging/maintaining another battery)? My desire is to play around with the motor controller modifications without worrying about the other electrical issue accessories.

Thanks in advance for replies. Regards JJ

 

[Jeremy Harris]

I would very strongly suggest doing some basic voltage checks with a meter, rather than trust any wire colour codes. You may well find that the 12V supply from the regulator isn't enough to charge a 12V battery, if that's what you had in mind, as you need at least 13.5V, perhaps 14V, to keep a small 12V battery charged up.

Why would you want to add a 12V battery when you've already got a 48V one? This set up, with the DC DC converter is fairly efficient as well as being lighter and smaller than having an extra battery and charging circuit.

If you're planning on increasing the main battery voltage, then I'd suggest that it'd be better to just replace the existing 48V to 12V converter with another with a wider input voltage range. You may well find that the 48V one can be modified, or perhaps already has the capability, to accept a higher input voltage. I provided a 12V supply on my small motorcycle conversion using a cheap 20A DC DC converter bought from ebay as surplus. It accepts anything from 36 to 72V at the input, giving me a wide range of battery voltages I can use.

 

[Milou]

Why would you want to add a 12V battery when you've already got a 48V one? This set up, with the DC DC converter is fairly efficient as well as being lighter and smaller than having an extra battery and charging circuit.

Thanks, this answers one of my questions. The setup I had in mind is to slide a 12V battery into a "DIY slot" to power the 12V circuit. Charge those batteries like a power tool method separately from the motorcycle scooter electrical system.

I would very strongly suggest doing some basic voltage checks with a meter, rather than trust any wire colour codes.

You are correct about the Chinese color code "trust". I got corrected and made the adjustment on the original post. I took out all the wiring harness and lay it out on the table to hand trace the wires. I discovered there can be lots of color wiring changes to one line!!! They tend to taps into lines at some "Chinese logical" random order. At least, in the end it seems to work???