Hi I’m a complete noob to PCB design but I’m needing an efficient(90%+) way to convert 48vdc to 12vdc.

My input is 48v(52.8v) solar batteries and my load is 12-15vdc at around 100 amps ~1500 or so watts.

 

big power costs $. Here's one:
https://safiery.com/product/scotty-ai-15kw-12-48v-canbus-bi-directional-dc-to-dc/

 

big power costs $. Here's one:
https://safiery.com/product/scotty-ai-15kw-12-48v-canbus-bi-directional-dc-to-dc/

That’s no fun tho! I want to make my own lol

 

That’s no fun tho! I want to make my own lol

Good luck with that. That sort of DC to DC power requires serious engineering design skills.
https://www.ti.com/tool/WEBENCH-CIRCUIT-DESIGNER
What power engineering have you done in the past?

 

No experience that’s why I’m asking for help…

 

OK, the TS could still build their own system, but purchase a 48:12 volt switcher supply, and assemble the rest. Please understand that the actual design of a switching mode power supply involves a lot more that just the circuit. In most switcher designs, every connection is also a circuit element that the resistance and reactance must be understood and considered.

 

Build a smaller version first. Maybe 10A or 5A. When you have that going then step up.

 

No experience that’s why I’m asking for help…

Have you ever designed a switching power supply or any power electronics? I'm only asking because those with No Experience often rush in where Where Angels Fear To Tread.

 

Your chances of success with no experience in power electronics will be vanishingly small. As mentioned you need to learn to crawl and walk before running a marathon.

The progression should go something like 5 watts, 50 watts, 500 watts, and 1.5 Kwatts. If you put yor nose to the grindstone and are succesful with the three predecessors, then you might have a fighting chance at your ultimate goal. You will not get there overnight and it might be 18-24 months before you do.

 

Build a smaller version first. Maybe 10A or 5A. When you have that going then step up.

Or parallel those circuits to a single output, right?

I have multiple of these 12v loads should I run 4 of them in series? Is there something I’m not thinking about using that configuration?

So 48v battery wired to 4x 12v loads in series?

 

Your chances of success with no experience in power electronics will be vanishingly small. As mentioned you need to learn to crawl and walk before running a marathon.

The progression should go something like 5 watts, 50 watts, 500 watts, and 1.5 Kwatts. If you put yor nose to the grindstone and are succesful with the three predecessors, then you might have a fighting chance at your ultimate goal. You will not get there overnight and it might be 18-24 months before you do.

24 months for what?…. I installed and manage a 100kw solar array… I seriously doubt designing a pcb to convert 48v to 12v is a 24 month project.

 

Ok you installed an manage a big solar array, as I have, but you didn't design any of the power electronics, as I didn't either. I just watched them burn and replaced them when they did. Power electronics at high efficiencies is an art.

Aiming at 1500W at 90%+ efficiency from a standing start - you are going to discover a lot that you don't know.

 

So 48v battery wired to 4x 12v loads in series?

It looks like you are charging 12V batteries. (12 to 15V) The simple thing is to stack up the batteries.
It looks like your panel is 48V and 25A.

What data do you have on the panel. There might be a voltage, current curve.
What batteries. Can they take 25A for hours?

 

24 months for what?…. I installed and manage a 100kw solar array… I seriously doubt designing a pcb to convert 48v to 12v is a 24 month project.

Sorry, but it doesn't work that way in the real world.

The reality is power electronics is an area of general electrical engineering and design that, at the circuit level, takes real education and experience, not hope.

https://engineeringonline.ucr.edu/blog/power-electronics-and-engineering/

 

It looks like you are charging 12V batteries. (12 to 15V) The simple thing is to stack up the batteries.
It looks like your panel is 48V and 25A.

What data do you have on the panel. There might be a voltage, current curve.
What batteries. Can they take 25A for hours?

They’re 48v 100Ah batteries with 1C discharge rating.

 

Sorry, but it doesn't work that way in the real world.

The reality is power electronics is an area of general electrical engineering and design that, at the circuit level, takes real education and experience, not hope.

https://engineeringonline.ucr.edu/blog/power-electronics-and-engineering/

I don’t need a diploma to do things. Don’t waste your life standing behind a piece of paper. If you want to learn/do something you will. A piece of paper isn’t going to tell me what I can and can’t do.

 

I have multiple of these 12v loads should I run 4 of them in series?

You have the panel and 48V batteries.
You just need to power 4 x 12V loads. 25A each.

If you series the 4 loads, the voltage across the loads will change. Is that OK?
You can make 4 independent 48V to 12V at 25A power supplies. The voltage will not change.

 

....designing a pcb....

I've just realised you keep talking about designing a PCB. Do you already have a circuit for a 1500W converter? If so then you have the hard part done, although even the physical design of PCB and enclosure are not simple if you haven't done it before.

 

So 48v battery wired to 4x 12v loads in series?

It would help answer if you described the loads.

If the loads are constant current (ie a simple behaviour profile similar to a resistor) then they can go in series. If the loads are varying in their power demand, then putting them in series will vary the proportion of the total voltage that each sees as their loads change.

 

I think the loads might be heating elements which is a very different thing. Most 12V heating elements could be run at 48V at 25% duty cycle. This could have regulation, so the duty cycle changes to keep the heat the same. This would take the inductor out and maybe the diode.