Setting up a new 24v system in a 12v RV and are new to this-- need info

[John Frum]

Here is a preliminary textual representation of your system topology.
Its human readable.
The legend block explains all the atoms in the dc_domain block.
It doesn't include a dc2dc converter or shunt.

 

[HJEngland]

Hi, thanks for the tips.

I did a power audit and I'm good in that respect.

I was looking get information/advice on two things:

A recommendation for a good step down converter- My system is 24v and the rv is 12v.

A possible wiring diagram to include a step down converter.

If you have any info on that I would greatly appreciate it!

 

[John Frum]

This is what I suggest for the positive busbar

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This is what I suggest for the negative busbar.

Amazon.com : MidNite Solar Busbar MNTBB-B : Solar Panels : Patio, Lawn & Garden

Amazon.com : MidNite Solar Busbar MNTBB-B : Solar Panels : Patio, Lawn & Garden

www.amazon.com

 

[HJEngland]

Here is a preliminary textual representation of your system topology.
Its human readable.
The legend block explains all the atoms in the dc_domain block.
It doesn't include a dc2dc converter or shunt.

I appreciate you taking the time to do this for me.

 

[John Frum]

updated topo to include dc2dc_converter

 

[John Frum]

I did this really fast on 1 cup of coffee.
Will double check it tonight for errors.

 

[John Frum]

This is the dc2dc converter I suggest.
The 70 amp one.

Orion DC-DC Converters Non-isolated, High power - Victron Energy

Eliminate the need for a high current switch in the input wiring with the remote on/off connector on the Orion DC-DC Converter. Find a dealer near you.

www.victronenergy.com

 

[John Frum]

This is the surge protector

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We have not specified a solar charge controller and we don't know the string configurations or string voltages so this is tentative.

 

[John Frum]

Because this is a stationary setup you can use THHN wire within the trailer which is cheaper and easier to source than high quality welding cable.

 

[HJEngland]

updated topo to include dc2dc_converter

thank you again! I appreciate all your help.

 

[chrisski]

This is the dc2dc converter I suggest.
The 70 amp one.

Orion DC-DC Converters Non-isolated, High power - Victron Energy

Eliminate the need for a high current switch in the input wiring with the remote on/off connector on the Orion DC-DC Converter. Find a dealer near you.

www.victronenergy.com

@HJEngland I have that converter. I like it. My max DC loads are a few seconds at 50 amps 12 volt and 12 amps 12 volts for hours on end.

It pulls enough power where it sparks when connected to power. To prevent sparking, I’ve tied my three sparking devices (3000 watt inverter, DC to DC Converter, and AC to DC converter) to a precharge resistor. No more spark. Prior to adding the resistor, the spark would happen inside the BLUE SEA 350 amp switch and I’d see it through the thick plastic casing. My RV is not stationary and I cycle power on and off dozens of times a year.

 

[John Frum]

@HJEngland I have that converter. I like it. My max DC loads are a few seconds at 50 amps 12 volt and 12 amps 12 volts for hours on end.

It pulls enough power where it sparks when connected to power. To prevent sparking, I’ve tied my three sparking devices (3000 watt inverter, DC to DC Converter, and AC to DC converter) to a precharge resistor. No more spark. Prior to adding the resistor, the spark would happen inside the BLUE SEA 350 amp switch and I’d see it through the thick plastic casing. My RV is not stationary and I cycle power on and off dozens of times a year.

Just to keep the topology flatter I will add a pre-charge resistor to the inverter_charger circuit.
Since this is a stationary always on setup for dc2dc converter I think its suffficient to just use a handheld resistor when connecting the converter.

 

[John Frum]

Updated topo
separate ground busbar
removed pv surge protection because the earth reference may or may not exist.
Added disconnect switch with pre-charge resistor.

 

[John Frum]

Here is some doco on pre-charge switches.

Inverter Disconnect Switch with Precharge

To get the paper, click on the orange button at the top of this page. This circuit is designed as a disconnect switch that allows the user to pre-charge the inverter capacitors before turning the switch completely on. 26 June 2020 update: At...

diysolarforum.com

 

[John Frum]

Just to keep the topology flatter I will add a pre-charge resistor to the inverter_charger circuit.
Since this is a stationary always on setup for dc2dc converter I think its suffficient to just use a handheld resistor when connecting the converter.

@chrisski does your converter spark if their is nothing connected downstream?

 

[chrisski]

@chrisski does your converter spark if their is nothing connected downstream?

Yes, with nothing at all connected to the 12 volt side. Whenever the 24 VDC circuit is made hot, it does spark. I contacted AIMS about this and who replied a little sparking is natural.

This does not spark nearly as much like a 3000 watt inverter, but sparked nonetheless so I included it on the pre-charge circuit.

 

[John Frum]

I contacted AIMS about this and who replied a little sparking is natural.

You mean Victron right?

 

[chrisski]

You mean Victron right?

I meant Victron.