Help with Ebike Headlights

[Tmt597]

Hi, so I recently built my first ebike, and I'm having trouble figuring out how to setup the headlight. It's a 3000w ebike with a Sabvoton SVMC7280. I've read that you need a DC-DC converter to step down the voltage from the 72v my battery outputs to 12v that an LED light can handle. I've been looking at DC-DC converters such as this one on Amazon: https://www.amazon.com/Pro-Chaser-regulator-Scooters-Bicycles/dp/B07B6B6HQZ/ref=sr_1_2_sspa?crid=Q52DUJWPR3X&keywords=72v+to+12v+converter&qid=1667491660&qu=eyJxc2MiOiIzLjU5IiwicXNhIjoiMy42MiIsInFzcCI6IjMuMzcifQ%3D%3D&sprefix=72v+to+12%2Caps%2C91&sr=8-2-spons&psc=1&smid=A36QA5X1QRFR3C

My concern is that all the DC-DC converters like this one I'm seeing advertised on Amazon are rated for somewhere around 180w, and I'm worried that if I connect it to my 3000w battery, the converter is going to explode or something. Am I missing something, or will this converter work? Sorry if this is a stupid question, I'm still new to all this and learning.

Thanks in advance!

 

[tomjasz]

OR get a light capable of being wired into the 72V power out and use a tap like the Anderson Tap from Grin. I bought the self-reset fuses they use and make my own with compatible connectors.

I don't like the added complexity of a DCDC PCB.

400 Lumen Ebike Light, Handlebar On/Off Push Button, 6-85V Input Range, and StVZO Compliant Optics. Can be Powered from Cycle Analyst

 

[TrotterBob]

Just because your battery can output 3,000 watts doesnt mean a bike light or a DC-DC converter will burn out due to an overcurrent situation. My question is why would you bother trying to step down from 72v to 12v when you could just get a bike headlight with a built in battery?

This is the one I'm using:

https://www.tattu.com/products/tattu-bl005-rechargeable-bicycle-headlight-2400-lumen-led-lamp-with-mount-18650-batteries-inside-and-micro-usb-charging-cable

Its good for just under 6 hours of run time on a single charge. Charging is a bit slow as it only charges at 800mah thru a standard micro USB cable.

 

[TrotterBob]

The wording on the Scamazon page for that DC DC converter is a bit suspect. As long as the voltage is within the correct paramaters the size of the battery does not matter one bit. That 180 watt rating is for the output so you wouldnt want to use a device that requires more than 15 amps.

"DC-DC 120V 108V 96V 84V 72V 60V 48V to 12V step down voltage reducer works at 180W power with 15A current. Please carefully check the working power of your battery pack. The item in current page should not be connected to any power source with power higher than 180W."

I'm not an electrician but even I know that is total BS.

 

[amberwolf]

Hi, so I recently built my first ebike, and I'm having trouble figuring out how to setup the headlight. It's a 3000w ebike with a Sabvoton SVMC7280. I've read that you need a DC-DC converter to step down the voltage from the 72v my battery outputs to 12v that an LED light can handle.

Before we can help you pick the right way, you must provide some details about the light itself, and your intended usage.

What voltage range does it operate from?

How much current (A, Amps) does it draw, maximum, in use?

Do you want the light to come on automatically when you turn the bike on?

Or would you rather switch it on separately?

If separately, do you want it to work when the rest of the bike is off, or only when the bike is on?

Will anything else on the bike also run from the same voltage as the light?

If so, how much current does each of those things draw, maximum?

Will you want those to come on automatically, or switch each one on separately, etc?