wiring *both* 24V and 12V appliances

[satanas]

Hi! I searched the forum and couldn't find this specific question posed ~ seems pretty obvious but here goes:
what if I have a 24V battery bank and would like to power *both* 12V and 24V appliances? I read that using 24V appliances wherever possible within a 24V system is preferred... so if I had a DC-DC 24V > 12V step down converter that feeds into a AC/DC fuse block distribution center where I connect all the wiring for my 120 AC & 12V appliances, would I then hookup the 24V appliances separately directly to the lynx distributor/battery bus bars?

major equipment for more clarification :
4x 200W 24V rich solar panels wired in series-parallel
6 SOK 100Ah aux batteries wired in series-parallel for 24V/300Ah
victron 150V/45A charge controller
victron lynx distributor
DC-DC 24V > 12V step down converter
Furrion AC/DC distribution panel
AIMS 3000w 24v inverter/charger? (haven't bought yet)

12V appliances:
compost toilet fan
2x maxxfans
puck lights

24V appliances:
fridge
water pump

thanks so much for bestowing me with your wisdom!

 

[rmaddy]

I have a similar setup. The basic idea is that you need a 12V fuse box (which is part of your AC/DC distribution panel) and a separate 24V fuse box. The 24V fuse box gets wired to the battery busbars like most things. The 12V fuse box is connected to the output of the 24->12V step-down converter. The converter is connected to the busbars. Proper fuses as needed.

It is more efficient to get as many 24V hookups as you can. I have a bunch of 12V LED puck lights. I put them on the 24V fuse box by wiring the lights in pairs connected in series. I've only used the lights in this setup briefly since I'm still building my trailer but so far they are working, even with a dimmer. At the moment I have three sets of puck lights in 2S1P, 2S2P, and 2S5P.

On my 24V fuse box I have the fridge, water pump, various LED lights, and the mobile router. On my 12V fuse box I have 2 Maxxair fans, composting toilet fan, Propex heater, propane detector, and 12V DC outlets.

Here's my schematic:

 

[satanas]

I have a similar setup. The basic idea is that you need a 12V fuse box (which is part of your AC/DC distribution panel) and a separate 24V fuse box. The 24V fuse box gets wired to the battery busbars like most things. The 12V fuse box is connected to the output of the 24->12V step-down converter. The converter is connected to the busbars. Proper fuses as needed.

It is more efficient to get as many 24V hookups as you can. I have a bunch of 12V LED puck lights. I put them on the 24V fuse box by wiring the lights in pairs connected in series. I've only used the lights in this setup briefly since I'm still building my trailer but so far they are working, even with a dimmer. At the moment I have three sets of puck lights in 2S1P, 2S2P, and 2S5P.

On my 24V fuse box I have the fridge, water pump, various LED lights, and the mobile router. On my 12V fuse box I have 2 Maxxair fans, composting toilet fan, Propex heater, propane detector, and 12V DC outlets.

Here's my schematic:

holy cow this is amazing! SUPER similar to my setup!
was this the fuse box you used for 24V? https://www.amazon.com/Blue-Sea-Sys...ywords=24V+DC+fuse+box&qid=1621642028&sr=8-30

 

[rmaddy]

That's exactly the same one I have. For planning, that Blue Sea fuse box needs ring connectors with #8 holes for the branch wiring and the two main negative and positive terminals need ring connectors with #10 holes.

 

[AndyRonLI]

I have a similar setup. The basic idea is that you need a 12V fuse box (which is part of your AC/DC distribution panel) and a separate 24V fuse box. The 24V fuse box gets wired to the battery busbars like most things. The 12V fuse box is connected to the output of the 24->12V step-down converter. The converter is connected to the busbars. Proper fuses as needed.

It is more efficient to get as many 24V hookups as you can. I have a bunch of 12V LED puck lights. I put them on the 24V fuse box by wiring the lights in pairs connected in series. I've only used the lights in this setup briefly since I'm still building my trailer but so far they are working, even with a dimmer. At the moment I have three sets of puck lights in 2S1P, 2S2P, and 2S5P.

On my 24V fuse box I have the fridge, water pump, various LED lights, and the mobile router. On my 12V fuse box I have 2 Maxxair fans, composting toilet fan, Propex heater, propane detector, and 12V DC outlets.

Here's my schematic:
View attachment 49942

Tiny bit confused by this schematic. I think you are showing a spot where the 12V and 24V DC cross as a junction, and you need a jump.
Maybe make the 12V DC lines dashed?
ANdy

 

[rmaddy]

Tiny bit confused by this schematic. I think you are showing a spot where the 12V and 24V DC cross as a junction, and you need a jump.
Maybe make the 12V DC lines dashed?
ANdy

Any lines that cross at a 90º angle are not connected in any way in real life. They just cross in the diagram.

 

[wmgeorge]

Any lines that cross at a 90º angle are not connected in any way in real life. They just cross in the diagram.

I am impressed beautiful job on the diagram and wiring. Are you a full time RVer?

 

[rmaddy]

I am impressed beautiful job on the diagram and wiring. Are you a full time RVer?

Thanks. Yes, been full time since August.

 

[brackstone]

I have a question about this, with a 24v system two 12v batteries in series, why can you not centre tap off the battery bank for the 12v appliances same as an auto transformer or what I see from laptop computers. Only issue i see is the balancing of the batteries but this should rebalance when fully charged

 

[rmaddy]

I have a question about this, with a 24v system two 12v batteries in series, why can you not centre tap off the battery bank for the 12v appliances same as an auto transformer or what I see from laptop computers. Only issue i see is the balancing of the batteries but this should rebalance when fully charged

The imbalance will cause battery issues over time. The battery connected to the 12V loads will get drained more. Now your two batteries have a different voltage. The 24V charge source will constantly undercharge the overused battery and overcharge the underused battery. The issue will get worse and worse. It's just a bad plan.

 

[brackstone]

The imbalance will cause battery issues over time. The battery connected to the 12V loads will get drained more. Now your two batteries have a different voltage. The 24V charge source will constantly undercharge the overused battery and overcharge the underused battery. The issue will get worse and worse. It's just a bad plan.

Ok I did wonder, only working on theory electron flow, but can see the issue

 

[Rednecktek]

Ok I did wonder, only working on theory electron flow, but can see the issue

Stupid reality, ruining all my great ideas!

 

[12VoltInstalls]

3000w 24v inverter/charger? (haven't bought yet)

24V appliances:
fridge
water pump

Is there a specific reason for a 3000W inverter? (I live full time on a 1000W currently)
There’s a plethora of decent 12V pumps which leaves the fridge.
I’m not chiding you but I see no reason to go 24V in your situation. In my opinion.
There’s several advantages to 24V but I’m not seeing where you get the advantages they offer.

 

[Rednecktek]

With a 3Kw inverter it seems that 24v is kind of a sweet spot in DC voltage. Still not flamethrower levels of amperage through the fuses and only having to physically find space for 2 batteries at a time rather than 4 if you want to add capacity. 3Kw is also a good chunk of overhead with enough room for future expandability like AirCon or the like.

On top of that, 24v RV and marine stuff require finding a specialty store and paying through the nose whereas finding 12v stuff is your local auto store. Availability is often a factor. Yes, a 24v fridge might be a super efficient use of your battery system, but when it dies or something goes wrong where do you drive to and grab a new one? Last I checked Amazon doesn't overnight ship to "Third fence pole on the left, dead-dirt road, Middle of Nowhere, Nebraska.

Much like the high overhead of an AIO unit, it often just becomes another factor you have to plan for.

 

[12VoltInstalls]

whereas finding 12v stuff is your

So much stuff 12V on Amazon identical to dealers and half to quarter the price.

 

[pollenface]

A 100w panel and 120ah AGM cover all my 12v needs, usually just keeping all my other random 12v batteries maintained. I found those 24v-12v converters unreliable.

I have a question about this, with a 24v system two 12v batteries in series, why can you not centre tap off the battery bank for the 12v appliances same as an auto transformer or what I see from laptop computers. Only issue i see is the balancing of the batteries but this should rebalance when fully charged

They won't rebalance unless you have a balancer or change them to parallel for a day.
I use 2x elcheapo Ha01 balancers but I note there is a victron one which looks much better

 

[pollenface]

Here's my schematic:

Forgive my curiosity but how do people on here make schematics? Do you get pictures of all the products and correlate them in ms paint?

 

[Rednecktek]

Forgive my curiosity but how do people on here make schematics? Do you get pictures of all the products and correlate them in ms paint?

That's what I do, although I have seen a beautiful design via cut & paste on occasion.

 

[rmaddy]

Forgive my curiosity but how do people on here make schematics? Do you get pictures of all the products and correlate them in ms paint?

For my diagram I found all of the pictures of my components. I then used GIMP (open source image editing software) to make backgrounds transparent, scale, and cleanup the pictures as needed. Use your favorite image editing software for this. I then used Inkscape (open source drawing program) to make the actual wiring diagram. it's not a paint program (do not use MS Paint). Each line, image, and text can be moved and changed as needed. Paste the images, add the lines, rearrange things until it all fits, add text and other details. It takes a while to get just right, but worth it.

 

[Samtrois]

Forgive my curiosity but how do people on here make schematics? Do you get pictures of all the products and correlate them in ms paint?

You're probably not as still interested, but maybe others are.
I've just started planning a similar 24v system and found edrawmax. I think it started as basic flow charts, but it does have electrical circuit stuff, and I think you can put pictures in (I'm just using shapes and text at the moment)