DC-DC converter from 48V to 6V for E-bike light?

B

Bersekz

100 W
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Jan 26, 2018
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I got a Bafang BBSHD motor, which has a light cable output of 6V 0.5A = 3W which isn't enough for any decent light. I bought a really great e-bike light 6V that requires 12W, so 2A output instead of 0.5A. For this reason I think to connect it directly to my 48V battery using a DC-DC converter. The thing is, I cannot find any decent DC-DC 48V to 6V 2A for doing what I want...

The best I could find is this: https://www.aliexpress.com/item/High-Voltage-EBike-DC-DC-Converter-Buck-Step-Down-Regulator-Module-80V-72V-64V-60V-48V/32824239630.html?spm=2114.search0104.3.2.7d88e2e0dNCMpR&ws_ab_test=searchweb0_0,searchweb201602_1_10152_10065_10151_10344_10068_10342_10325_10343_10546_10340_5722611_10341_10548_10698_10697_10696_5722911_5722811_10084_5722711_10083_10618_10304_10307_5711211_10059_10184_308_100031_10103_441_10624_10623_10622_10621_10620_5711311_5722511,searchweb201603_28,ppcSwitch_5&algo_expid=93281559-2926-49f7-b9f6-52c07e8b625b-0&algo_pvid=93281559-2926-49f7-b9f6-52c07e8b625b&priceBeautifyAB=0

But it outputs 6V 1A = 6W which is half of what I need. Please help me somebody. :(
 
Search buck converter or step down, that's a very common voltage range at a easy power level.

This one's on ebay, but there are a million others https://www.ebay.com/itm/200W-15A-Voltage-Power-Buck-Converter-Step-Down-Module-DC-DC-8-60V-TO-1-36V-WF/371995503870?epid=594014616&hash=item569ca8ecfe
 
I use this for 16V lighting on a 52V bike but it will adjust down to your range as well.
Works nice.


DcDcConverter.png


EM3EV:
https://em3ev.com/shop/dcdc-converter/

Ed Lyen:
https://endless-sphere.com/forums/viewtopic.php?t=21459
http://lyen.com/

or search: QS-4805CBD-3A
 
If you use 4 automotive 12v lights on your bike, you can wire them in a series, thus needing no DC-DC converter.

You can also use 6: 2 small red on the rear, 2 low beam and 2 hi beam on the front, with a switching circuit to choose the hi or low.
 
racingame said:
I got a Bafang BBSHD motor, which has a light cable output of 6V 0.5A = 3W which isn't enough for any decent light. I bought a really great e-bike light 6V that requires 12W, so 2A output instead of 0.5A. For this reason I think to connect it directly to my 48V battery using a DC-DC converter. The thing is, I cannot find any decent DC-DC 48V to 6V 2A for doing what I want...

The best I could find is this: https://www.aliexpress.com/item/High-Voltage-EBike-DC-DC-Converter-Buck-Step-Down-Regulator-Module-80V-72V-64V-60V-48V/32824239630.html?spm=2114.search0104.3.2.7d88e2e0dNCMpR&ws_ab_test=searchweb0_0,searchweb201602_1_10152_10065_10151_10344_10068_10342_10325_10343_10546_10340_5722611_10341_10548_10698_10697_10696_5722911_5722811_10084_5722711_10083_10618_10304_10307_5711211_10059_10184_308_100031_10103_441_10624_10623_10622_10621_10620_5711311_5722511,searchweb201603_28,ppcSwitch_5&algo_expid=93281559-2926-49f7-b9f6-52c07e8b625b-0&algo_pvid=93281559-2926-49f7-b9f6-52c07e8b625b&priceBeautifyAB=0

But it outputs 6V 1A = 6W which is half of what I need. Please help me somebody. :(
Click to expand...

I have one of the below versions in 48 to 12v they make it in many different voltages and amp outputs. It has a small foot print and is waterproof.

You can find these on Amazon or eBay etc. I snagged the photo off a Amazon listing.

61v9JYJN3RL._SL1000_.jpg


Power Converter DC 36V 48V Step Down To DC 6V 5A 30W
 
So, what solution is better?

Something like this:

Dc-dc-12-v-24-v-36-v-48-v-a-6V3A18W-step-down-buck-module.jpg


or this?

file.php


I think the QSKJ isn't waterproof.
 
racingame said:
So, what solution is better?
...
I think the QSKJ isn't waterproof.
Click to expand...
Nope, it's not. You would need to box it. Depending on what other modules you might have that may or may not be an issue.

On one of my bikes that supply lives in this little aluminum box with a strobe module and an ebrake-signal-to-relay driver for a standard truck 12V brake light. In that application the small size was more valuable than weatherproofing. Different strokes.... :D


P1010543a_800.jpg
 
I have used two of those I purchased from same places you mentioned. $10 if I am not mistaken.


teklektik said:
I use this for 16V lighting on a 52V bike but it will adjust down to your range as well.
Works nice.


DcDcConverter.png


EM3EV:
https://em3ev.com/shop/dcdc-converter/

Ed Lyen:
https://endless-sphere.com/forums/viewtopic.php?t=21459
http://lyen.com/

or search: QS-4805CBD-3A
Click to expand...
 
I use the 6v to activate a solid state relay that can activate with anything from 3-32 volts. http://a.co/8KvbrY2 That way you don't need another switch on your bike and use the built in headlight feature.
41viIpmRjcL.jpg



I ended up using it on a light that can work between 12-80 volts. http://a.co/dE68Gzb
619t6vVHKIL._SL1200_.jpg


I have tested it on my 15 watt hid flashlight and connected it using an adjustable stepdown converter that I already own. http://a.co/2di9b5s
71afXQADCQL._SL1200_.jpg
 
esqueue said:
I use the 6v to activate a solid state relay that can activate with anything from 3-32 volts. http://a.co/8KvbrY2 That way you don't need another switch on your bike and use the built in headlight feature.
41viIpmRjcL.jpg



I ended up using it on a light that can work between 12-80 volts. http://a.co/dE68Gzb
619t6vVHKIL._SL1200_.jpg


I have tested it on my 15 watt hid flashlight and connected it using an adjustable stepdown converter that I already own. http://a.co/2di9b5s
71afXQADCQL._SL1200_.jpg
Click to expand...
So you did something like this:

sLT8swf.jpg


You connect the Bafang 6V cable into the relay and the relay to the light, right? Or there is also the http://a.co/2di9b5s in between the light and relay?
 
racingame said:
So, you did something like this.....
Click to expand...
Nope. What head lights do you plan on running? The light I posted above can operate on anything from 12v to 80v so that completely eliminates the need for a dc-dc converter as it already has one built in. If your light needs a specific voltage, you will need a dc-dc converter to drop it from Battery voltage down to whatever volts your light operates at.

So with your light connected directly to power, you need a way for the BBSHD to turn it on and off and that's where that relay comes in to play. When pins 1 and 2 gets any voltage from 3 and 32 volts DC, it allows the flow of current between pins 3 and 4. It is basically an on and off switch. Pins 1 and 2 gets connected to the 6v output of the BBSHD. Pins 3 and 4 will go in between either the positive or negative side of your circuit to your headlight. When when you turn on the headlight via the BBSHD and it sends 6 volts to pins 1 and 2, it will connect pins 3 and 4 which will send 48 volts to your headlight or to your dc-dc converter then headlight.

I wish I could make a schematic.
 
I attempted to make a drawing. That is a picture of a 36v (now 48v) battery that I made using hoverboard packs and a diy spot welder thanks to online research. Remember, if you need a specific voltage for your lights, the power cables going to the headlights would instead go to the dc-dc converter and the new reduced output to the headlights.




Dumsterdave said:
What are some good lights to use?
Click to expand...

I recommend the light that I posted above. It costed me $12.39 USD but I see it on ebay for under $15 USD.
 
esqueue said:
I attempted to make a drawing. That is a picture of a 36v (now 48v) battery that I made using hoverboard packs and a diy spot welder thanks to online research. Remember, if you need a specific voltage for your lights, the power cables going to the headlights would instead go to the dc-dc converter and the new reduced output to the headlights.




Dumsterdave said:
What are some good lights to use?
Click to expand...

I recommend the light that I posted above. It costed me $12.39 USD but I see it on ebay for under $15 USD.
Click to expand...

You @esqueue are a life saver! I am about to install a BBSHD on a fat bike with 52v battery and really like your solution for the headlight. I have the same light you have on another bike and love it indeed. I have a few questions for you though:

- What did you do with the relay once soldering done to hide/protect/waterproof?

I suck at electric stuff unless I have clear instructions/images to figure things out, then I manage fine. How would you properly and safely connect the + and - wires to the battery pack? I will have a shark type battery.

Finally, would it be a good idea to put a fuse on the positive wire between the battery and pin # 4 (or would it go elsewhere?) to prevent potential short/overheating and what type would you use?

Thanks for your help!
 
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