Voltage Converter Location?

Jamr · May 25, 2022

I am doing a Inverter/Battery conversion and have a question about the location of the 24 to 12vdc step down converter.

My batteries are going to be in a 24vdc configuration and need a step down converter to power the trailers 12 volt systems,

The inverter and batteries are in a storage box in the front of the trailer and the 110 breaker/12 fuse box is located about 2/3rd of the way down the trailer (20' distance from each other). There are already two 6 gauge wires ran to and from each of these locations for the old battery charging system. I want to utilize these wires for the 12volt supply to the fuse panel from the 24vdc batteries which means I will need to step down the 24vdc to 12vdc for this 12vdc supply to the fuse panel.

My original thought was to put the step down converter at the batter location which will then step down the voltage to 12vdc for its travel to the fuse box about 20 feet away.
Then I thought that it might be better to leave the voltage at 24vdc at the battery end and put the step down converter at the fuse panel where it will be converted to 12vdc inches away from the fuse panel input to reduce voltage loss for that 20'
I am removing the old batter charger at the fuse panel location so I have a perfect well ventilated area for the step down converter.

Any thoughts?

I see two 40amp fuses as my main input fuses on the 12vdc side so I am assuming I need a 40amp step down converter to power everything. Is this correct?

If so, I am looking at this converter (24-12 40amp version). Anyone tried this device? Thoughts?

Thanks for your time and advice.

GlennWest · May 25, 2022

Do you have hydraulic jacks or slide outs? If so you will need a lot more than 40 amp.

Jamr · May 25, 2022

36 minutes ago, GlennWest said:

Do you have hydraulic jacks or slide outs? If so you will need a lot more than 40 amp.

Yes. I have one slide out and two electric stabilizers, and one electric hitch lift.
I guess they draw more than 40 amps?

Do you have any idea how I find out how much they draw?

Thanks for the help.

GlennWest · May 26, 2022

Is the slide out hydraulic or electric? Most hydraulic systems on auto reset relays. Not run thru fuse panel. If all electric, it should be on fuse panel.

GlennWest · May 26, 2022

I have a 48v system. Have a 48/70 amp converter. Lights in camper will go out when slides are being used. Mine are hydraulic.

Jamr · May 26, 2022

The slideout is electric. It is fused with a 15amp fuse. Maybe this is just for the slide relay?

I will attempt to get help tomorrow reading the battery lead with my meter to see how many amps are being pulled when the slide is being used.

GlennWest · May 26, 2022

Ignore my post then. Hydraulic systems are power hungry and that why I brought this up. If you are all electric and gas the 40 amp should work as long as that covers your load. Have you considered the Victron unit? Just goggle Victron DC/DC converter. The unit you linked does 12v. The Victron does 13+ and is adjustable. Some of you load may perform better. Also step down converters tend to loose some volts near top of output. Factory converters output 13 volts. Batteries charged up are 13 volts. My advise is stay 13 volts.

https://www.amazon.com/Victron-Energy-Orion-12-40A-Converter/dp/B073PFD2GJ/ref=pd_aw_lpo_1?pd_rd_i=B073PFD2GJ&psc=1

Edited May 26, 2022 by GlennWest

Jamr · May 26, 2022

Yea, all my other stuff is Victron. I was trying to save some $$ with the original unit I posted. I might as well stay with the same manufacture. Which leaves only one question now. How big?
The 40 or 70 amp version. I will try to do some tests today to figure out my draw.

Anyone else know how to test this?

Getting back to that. I realized after posting that I have a 12vdc electric hitch lift at the front of the trailer which is grabbing power at the front end which means I will have to mount the step down converter at the front end with the inverter and batteries.

Thanks again for anyone's help.

Chad Heiser · May 27, 2022

You will have several 12 volt draws that do not run through the 12 volt power panel. These are typically jacks, slides and every once in a while some other random piece of equipment or lighting. The converter should be right after your 24 volt batteries and connect all of your OEM 12 volt battery connections after it (usually with a set of bus bars).

The Victron 24 to 12 volt converters are pretty good. I would recommend the 70 amp version to be on the safe side. I know of some larger rigs that require two 70 amp converters in parallel to run the large draw items.

Out of curiosity, what made you go with a 24 volt system?

Jamr · May 28, 2022

Yes, I picked up a 70A a few days ago and it is already delivered.

I did test my slides amp usage at 18A when being used.

The reasons I went with a 24v system versus a 12v system is,
1. Lower Amperage
Lower materials cost for wire and fuses.

2. Future Battery Upgrades
I am figuring on 4 SOK 200A batteries but am only using 2 at the present time thus leading to even more amperage thus refer back to #1.

3. Future Solar Panel Scalability
Higher limits on solar input. (I read this somewhere but I am having trouble finding this in the specs anywhere.)

4. Weight
Weight is also an issue in my rig so I wanted to cut as much as I could with the extra bulky wire.

I realize you are a 12v proponent.

Thanks for the help.

Chad Heiser · May 29, 2022

There is nothing wrong with a 24 volt system and in some circumstances they do offer advantages. It just requires additional equipment to get back to 12 volt for all the OEM systems.