Yes, DC-DC Buck Converters for automotive, heavy equipment, and aircraft systems. I don’t know how tight of a package you are trying to end up with or if room is an issue but did you see those I listed in #15? They are pretty cheap nowdays and other companies make similar with similar spec parameters.
We have been running two 150 watts each 38 volt 7 amp solar panels through just one of those Buck Converters extremely reliable so far. We set these panels up in pairs through one BC on it’s way to the charge controllers. We can input either 14 volts or 28 to the charge controller depending on if the system is a 12v or 24v system. And the heat sinks barely get warm in full charge conditions.
But the range capabilities of these and being adjustable is great. They can be used for just about anything you need them for and are extremely efficient.
Those are pretty cool, but, way more than what I need / want in terms of output capacity. And, I’m not sure about the constant current part: Since different loads will be presented, ie., I’ll switch in (”on”) anywhere from 0 to 8 LED modules, I don’t really want something that tries to push a constant current.
Then there’s also the bit I mentioned above about the lighting being its own indicator if the source (battery) voltage gets low. Conversely, here, if the battery voltage drops, the boost function will draw even more current from the battery, trying to maintain the converter’s output. Great way to really kill a battery.* The LEDS stay on nice and bright until suddenly you are plunged into darkness.
I could add something as simple as a relay circuit to disconnect the battery if battery voltage runs low, or, sound an alarm, but, this is getting much too involved...
I just want something that acts more or less like it wasn’t even there when the battery / source is at 13 volts or less, and drops the voltage to the load to 13 volts when the source (car charge system and battery) is greater than 13 volts. The zener regulator does that, but very inefficiently and requires big components to have much current capacity. The zener-transistor regulator MAY be ok as voltage drops, certainly with better current capacity than the zener regulator (which is really merely a voltage limiter), and the linear regulator I just don’t know.
*Different app, but I’ve discovered that a sharp decline at the end of a battery’s discharge cycle can be a serious disadvantage in many cases. A case in point is a smoke detector or a moisture detector (often used to tell you your sump pump has failed), usually powered off a 9v alkaline battery. Try to use a rechargeable battery and usually the battery is quickly “too low” and the low battery alarm sounds. (My “9 volt” [actually more like 8 volt] rechargeable lithium batteries work great with good “life” in many devices, but, not in smoke detectors.) Try to use the new rechargeable batteries with tiny boost converters in them to provide a stable / regulated 9 volt supply, and the battery voltage falls off a cliff toward the end of the discharge cycle. Instead of being away a couple days and coming back to a low battery alarm that may well have been chirping intermittently as designed since 2 minutes after you drove off, you come back to silence. Maybe that fire happens the next day, but the alarm never alerts you because the low battery alarm only sounded briefly while you were gone, and then IT died too. So poor resident dies too, clueless until too late. (Sounds like Biden voters, eh?)
That’s why smoke detector instructions always say to only use alkaline batteries — they have a “soft” gradual “death”.