24v battery inverter with 110/12v output

[jvbutter01]

In my TT, I am adding 2 - 12v lifPo batteries in series for 24v. I will have a 24v inverter mounted close to the batteries to supply the 110v for the power center. I can't have just 24v in the trailer. I have many motors that use 12v. Is there a device to easily step down 24v to a 12v output for power station. Keep in mind, the batteries/inverter is in front of trailer and 20ft to the rear is the 110v/12v power station. I do see there are many 24v to 12v converters. I worry about the amount of distance if I keep this 24v-12v converter in front.

would the best bet have 24v batt / inverter in front, sending 110v to the rear power center. at the power center, mount a 110v to 12v converter for the 12v motor needs?

Keeping 12v from start to finish will require upgrade in the main DC cable's from front to the rear, as well as increased hazard of pushing 150a front to rear. 150a max current for my 3000w inverter planned install.

idea of 24v to 12 came from will to use a 24v to 12 conv at the rear power center

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[Samsonite801]

24v can tolerate longer runs and smaller cable than 12v would (you still should use a gauge calculator whenever sizing for any cable run):

Voltage Drop Calculator

This free voltage drop calculator estimates the voltage drop of an electrical circuit based on the wire size, distance, and anticipated load current.

www.calculator.net

You could do a big dc-dc converter like this example:

https://www.amazon.com/Victron-Orion-12-70A-DC-DC-Converter/dp/B01BF5BQLA

Or multiple smaller buck converters like these examples:
20a:

Amazon.com: uxcell Voltage Buck Converter Regulator DC 24V to DC 12V 20A 240W Waterproof Power Transformer : Electronics

Amazon.com: uxcell Voltage Buck Converter Regulator DC 24V to DC 12V 20A 240W Waterproof Power Transformer : Electronics

www.amazon.com

40a:

https://www.amazon.com/uxcell-Converter-Regulator-Transformer-Waterproof/dp/B01LYK6G2Y/ref=psdc_10967761_t1_B01N63G8D2

Or I suppose if you wanted to get really fancy, you could add in a separate 12v battery and use a DC-DC battery charger like this:

https://www.amazon.com/Victron-Energy-Orion-Tr-Non-Isolated-Bluetooth/dp/B086L28Q43

Or a bigger one:

https://www.amazon.com/Renogy-Battery-Batteries-Multi-stage-Charging/dp/B07Z4GSYC2/ref=sr_1_1?dchild=1&keywords=dc%2Bto%2Bdc%2B24v%2Bto%2B12v%2Bbattery%2Bcharger&qid=1605587739&sr=8-1&th=1

Or you could just keep all 12v and install big fat cables where needed (use the gauge calculator)... My 38ft motorhome has 12v everywhere from the factory (the Magnum 2800w inverter is about 10ft away), not sure what gauge it has but is super heavy gauge.

I recently installed an AIMS 2500w inverter for my friend's RV trailer and it needed a 25ft run which we calculated to use 3/0 awg cable and it cost $178
I just checked and they don't show that seller has that 25' Red/Black in 3/0 awg, but checking now, they have 2/0 (is one size smaller) for $146

https://www.amazon.com/gp/product/B00LIB6PF4/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&th=1

Looks like a lot of sellers are out of 3/0 welding cable right now...

Anyways yeah, food for thought, it's a matter of personal preference I guess. Me personally, I don't see a problem with keeping 12v on an RV where everything's made to run on 12v, just make sure I use big fat cable, and make sure all the connections are good, fuse protection, etc... But 24v fine too, if you don't mind making the changes to work around the 12v accessories.

 

[jvbutter01]

yes I did do the calculator that is how I found out my existing 6g would work for my 20ft run. Also the reason I am considering 24v system rather than 12 and 2/0 cables front to rear.

whoooo that's good sized at 70a... that is more than my power box now. Yes I see the 25a model. I think that is what I would use. Alot better unit that the cheap DC/DC converts I found. Yes like the uxcell.. that would do the work, but longevity? I dont mind paying a little more for better equipment. I don't want to be stuck out in boonies and cant get jacks up... No fun.

no no no... 1 battery system.
running new wires involves dropping the "weather package" covering under the trailer.. and for 30ft trailer, that's a lot of screws. so unless I have to, I will pass.

thx for you input

 

[Samsonite801]

Sure no prob at all, sounds great!

If you were a little worried about longevity on them, just buy a couple spares to carry onboard in your spare parts bin, until at least you know they are rock-solid (or else if they blow out every once in awhile hehe)...

 

[jvbutter01]

in a Travel trailer / RV, weight is always a concern. At home, I'm all about having spares - backup plan. On the road, we try to keep "extras" at home. Weight is our enemy.