Ebike92119 said:
I’d like to install a bright LED light bar on my ebike as a headlight,
Keep in mind that the light bars you're probably looking at do not have anything to prevent the light from blinding others on the road that are facing you. I don't recommend using any of them for on-road use, or where others are likely to be in the light path from them, as they may be blinded by the light and then unable to see where they are going, and they may crash, or hit other people, etc.
If you want a bright light for use where anyone else might end up facing it, use only those that have "horizons" that mask or reflect the light that would go upward back down onto the ground--it makes them more effective and less of a hazard to other people.
There are motorcycle and ebike lights that have horizons and are pretty bright, that will run directly off your ebike battery (they have their own converters). I don't know which are good, but there have been threads about various brands. If I didn't already have my Kia headlight, I'd've gone with a motorcycle LED light.
But don't bother using a lamp assembly designed for incandescent bulbs with any of the LED replacements--they just won't work as intended, and you won't get the light pattern they were made for, or the brightness. Tried that. :/
but most of the light bars are designed for trucks,12v. My ebike is 58v, I’d some how have to step down voltage, but DC voltage can not be stepped down.
Yes, it can. You want a DC-DC converter, also called a buck converter, with an input range that includes the entire voltage range of your battery from full charge to empty, and an output voltage of 13.6v (13-15v will work), as that's the actual typical voltage of an automotive system (using only 12v will not make the lights as bright as they were designed to be.
Is your battery 58v fully charged? If so, what is it's empty voltage? You'll need a converter that works thru the whole range or your lights will shut off when the battery voltage is outside the range.
The converter must also be able to supply the full current that the lights you're running off of it take. So if you have a "50w" light, that runs at "12v", it takes approximately 5amps to do this. (50 / 12 = 4.something, then round up). If it's a higher wattage light, it'll take more amps.
Is it possible to run lights designed for a car on an ebike?
Yes. My SB Cruiser trike uses a number of them, including a headlight from some Kia I found in a parking lot after someone left pieces of their front end after a crash. Here's a post with some pics of my taillights (with brake and turn signals)
https://endless-sphere.com/forums/viewtopic.php?f=2&t=67833&p=1629240&hilit=cruiser+trike#p1612115
Elsewhere in the thread there are posts about the various other lights on the trike.
I use a separate battery for the purpose, so that my lights will work even if my motor/controller battery is empty or has failed. But I've also used DC-DC's off the traction battery and that works too.
