Where to connect DC/DC Buck Conveter

[Jeffrey207]

Hello everyone! I'm currently in the process of setting up a 24V solar system in my van. Given that I have devices requiring both 12V and 24V, my approach involves having separate fuse blocks—one for 24V connections and another for 12V connections. To power the devices requiring 12V, I'll be utilizing a DC/DC buck converter to step down the voltage from 24V to 12V. So my question is: since my battery will be linked to the 24V fuse block, where should I connect the buck converter? Would it be best to connect it directly to the 24V fuse block and subsequently to the 12V fuse block? Or, should I connect the buck converter directly to the battery instead of the 12V fuse block? I’m a beginner in this area and have been doing research into this setup throughout the past year. Any feedback would be greatly appreciated!!

 

[chrisski]

my question is: since my battery will be linked to the 24V fuse block, where should I connect the buck converter?

At a place that makes sense for your build.

For my build, I ran the 24 volts as close as practical to the 12 volt connection and put the converter there. For me, this is where the battery was already in, so the fuse block was down the line from there.

Amperage doubles when you go to 12 volts, so I did this to minimize voltage loss. I typically don't get above 10 amps, but using the heater but when I set the RV up, the leveling jacks take 500 watts.

 

[Jeffrey207]

Hey Chris, my main question is how do I connect all of these together. Would this work:

24V Battery > 24V fuse block > DC/DC buck converter > 12V fuse block.

Does the converter connect to both the 24V fuse block and the 12V fuse block?

 

[Jeffrey207]

Hey Chris! Appreciate your help on this. How did you wire in the converter in your system? Was it connected to both the 12v and 24v fuse block? Thanks!

 

[chrisski]

Hey Chris, my main question is how do I connect all of these together. Would this work:

24V Battery > 24V fuse block > DC/DC buck converter > 12V fuse block.

Does the converter connect to both the 24V fuse block and the 12V fuse block?

That is what I did to mine.

My fuse block was rated to 50 amps, so I put an additional 50 amp fuse block before it.

 

[chrisski]

Here is a pic from the RV build part II link in my signature block:

The 24 volt 50 amp fuse Fuse is installed by the main power busbar, and the 80 amp 12 volt fuse is installed ontop of the Orion. Both are ANL and are ABYC rated for main battery protect.

 

[chilly2]

That's a max of 640W. Do any of your 12v appliances surge?

 

[chrisski]

Hey Chris! Appreciate your help on this. How did you wire in the converter in your system? Was it connected to both the 12v and 24v fuse block? Thanks!

120 VAC Plug by the Main Circuit Panel-->Coverter 24 VDC-->8 Position Main Power BusBar-->24 Volt to 12 VOlt DC Converter-->Old battery 12 VDC connect.

 

[chrisski]

That's a max of 640W. Do any of your 12v appliances surge?

That's a hard question. No way to easily measure the "instant Surge" and even if you could, matching to the inverter or converter, you often have to buy large to be sure and hope it works.

When I bought this 12 volt 70 amp converter for the 12 volt 50 amp load, I knew that if it surged above the 70 amps, I could put more of the converters in parallel to handle the surge. Luckily, I did not need a second converter to handle the 50 amp 12 volt leveling jacks; the 70 amps 12 volts handled that.

 

[Zwy]

Hey Chris, my main question is how do I connect all of these together. Would this work:

24V Battery > 24V fuse block > DC/DC buck converter > 12V fuse block.

Does the converter connect to both the 24V fuse block and the 12V fuse block?

You need a fuse or breaker before the buck converter so it makes sense to pull power from the 24V fuse block if the buck converter is not high wattage. Once you get over 700W, it probably is best to use a DC rated breaker or T Class fuse. On my truck camper, the 24V fuse block is on one side of the camper close to the battery and the 24V to 12V converter is on the other side of the camper.

My buck converter is 720W, so the fuse/cable from the 24V block is 8AWG and runs about 12 feet long as it snakes over to the other side. After the buck converter is another fuse block which is all 12V. There is a circuit breaker between the buck converter 12V output and 12V fuse panel. 12V fuse panel is shown here.




And the buck converter is tucked in behind it. I used a busbar to connect the buck converter output to the breaker. Just remember the wire from the buck converter output will have twice the amps so you to size it appropriately. I went with a 720W buck converter as I plan on only pulling 1/2 the rated watts thru the buck converter. Too many overload Chinese made electronics and wonder why it failed. Mine has worked flawlessly and draws next to nothing at idle, I never turn it off even when the camper is stored for the winter.

 

[Jeffrey207]

@Zwy @chrisski Thank you both very much for your input. You both were extremely helpful!!! I get the gist of it now!