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Batteries in multiple locations on an older RV, what are the added challenges of a 24V system?

liveaxle

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I currently live in a 5th wheel with no off-grid electrical capability other than 2 aging marine lead acid batteries (38ah@12v usable).

I want to start my upgrade with a massive battery system, that will (eventually) utilize 2 battery banks, a house inverter and 2 micro-inverters. The battery banks will be mounted (approx.) 25 feet apart, with most of the charging infrastructure on one end. I am leaning toward a 24V 200AH server rack battery near my primary inverter and 24V 100AH (likely in the form of 2x100ah12v) 25 feet away behind my fireplace. I would like to go with a higher voltage to allow lower current between the 2 banks, but I want to sanity check the challenges I am looking at for using 24V batteries.

The challenges I am expecting with the higher voltages are:

Needing a 24V to 12V DC-DC to power the existing loads in the system.

Needing a 12V to 12V DC-DC to charge the batteries from my truck when towing (DC-DC will be required to protect my alternator anyway, regardless of voltage)

Needing a 24V AC-DC charger to charge from shore power. (Will need a new charger anyway for LiFePO batteries)


For those who are using 24V+ batteries on existing 12V RVs, am I missing anything with this list of challenges?
 
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I currently live in a 5th wheel with no off-grid electrical capability other than 2 aging marine lead acid batteries (38ah@12v usable).

I want to start my upgrade with a massive battery system, that will (eventually) utilize 2 battery banks, a house inverter and 2 micro-inverters. The battery banks will be mounted (approx.) 25 feet apart, with most of the charging infrastructure on one end. I am leaning toward a 24V 400AH server rack battery near my primary inverter and 24V 100AH (likely in the form of 2x100ah12v) 25 feet away behind my fireplace. I would like to go with a higher voltage to allow lower current between the 2 banks, but I want to sanity check the challenges I am looking at for using 24V batteries.

The challenges I am expecting with the higher voltages are:

Needing a 24V to 12V DC-DC to power the existing loads in the system.

Needing a 12V to 12V DC-DC to charge the batteries from my truck when towing (DC-DC will be required to protect my alternator anyway, regardless of voltage)

Needing a 24V AC-DC charger to charge from shore power. (Will need a new charger anyway for LiFePO batteries)


For those who are using 24V+ batteries on existing 12V RVs, am I missing anything with this list of challenges?
You need to find out what the loads are from your levelers and slide outs. Often there is to much start ups amperage required for a simple converter to operate these devices. Sometimes people opt to leave their existing 12v system in tact and simply invert to 120 and convert back to 12 or some other method of having a battery to absorb the extreme amps required to spin up “large” electric motors under load.
 
My levelers are manual and my slides are hydraulic.

I am trying to get specs on my pump (its out of production, I have reached out the manufacturer) and find out if it can run on 24V.

Modern 12V pumps pull 40-80 amps.
 
One of the reasons for going 24V instead of 48V is the hope that I can run the pump on 24V or find a 24V replacement.
 
I don't know what you have for a factory power/load center but I have a WFCO 8955 in my trailer. The garbage converter/charger pulls right out and a Victron Orion 24/12/70 converter fits perfectly in it's place. Very easy replacement. Powers all my house 12v DC including the slide, which pulls about 30 amps with power to spare. And it's a regulated voltage too, no sagging.

MZig4bXl.jpg
 
If you do go 24 volt, skip the 12 volt batteries in series and get a battery that is 24 volt. You'll have fewer problems that way.

If you get an inverter/charger then you can ditch the AC-DC converter.

I don't understand the need for two battery banks. Can you explain that in more depth?
 
I hardly call that battery massive. OK maybe it is compared to the existing.
How large of inverter? Can't imagine needing over 2000 watts and works fine on 12 volts and could simplify a lot of up-down issues.
 
My levelers are manual and my slides are hydraulic.

I am trying to get specs on my pump (its out of production, I have reached out the manufacturer) and find out if it can run on 24V.

Modern 12V pumps pull 40-80 amps.
I ran into this video a month or so ago. It’s a rather elaborate 48v system and the fellow used three 48v to 12v Orion converters in parallel and apparently was still unable to overcome the surge of his hydraulic motor for the slides and ended up using a separate battery to do what he wanted. The part where he explained that is roughly 6 minutes into the video.
 
My levelers are manual and my slides are hydraulic.

I am trying to get specs on my pump (its out of production, I have reached out the manufacturer) and find out if it can run on 24V.

Modern 12V pumps pull 40-80 amps.
I have been living in boats and RVs for 25 years… what kind of 12v pumps are you using that pull 40 to 80 amps…what are they pumping… even a macerator toilet pump doest pull that much juice….
I have 4 name brand 12 volt pumps onboard now .. they all draw about 5 to 7 amps at typical 3 to 5 gpm of discharge.. …large 12 v bilge pumps (3000 gph) pull about 15 amps….I must be must be missing somthing..
 
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I have been living in boats and RVs for 25 years… what kind of 12v pumps are you using that pull 40 to 80 amps…what are they pumping… even a macerator toilet pump doest pull that much juice….
I have 4 name brand 12 volt pumps onboard now .. they all draw about 5 to 7 amps at typical 3 to 5 gpm of discharge.. …large 12 v bilge pumps (3000 gph) pull about 15 amps….I must be must be missing somthing..
I had understood that he was referring to hydraulic pumps. The ones used for slide outs and levelers on an rv.
 
Just put a clamp meter on the current battery bank and run the slide in/out.
That will give you a good idea of what you need to accommodate and what size BMS you will need for the load.
LCA doesn't care if it's a sudden peak load, but a BMS sees those same sharp loads as short.
 
I had understood that he was referring to hydraulic pumps. The ones used for slide outs and levelers on an rv.
I hope so… haaa. I racked my brain over that one…thought it was a typo. I do have 2 14 ft slides on my present rv and a landing gear jack that will draw pretty good amperage .levelers are manual ... thanks for the clarification…jim.
 
I put a 24 volt system in our 2007 Triple E fifth wheel. I used the Victron 24/12/70 dc to dc conveter for my 12v needs. It powers my big slide better then when i'm on shore power. It isn't hydraulic though. I am super happy with the 24v system. I only power one leg of the A/C panel when on inverter though.
 
I don't know what you have for a factory power/load center but I have a WFCO 8955 in my trailer. The garbage converter/charger pulls right out and a Victron Orion 24/12/70 converter fits perfectly in it's place. Very easy replacement. Powers all my house 12v DC including the slide, which pulls about 30 amps with power to spare. And it's a regulated voltage too, no sagging.

MZig4bXl.jpg
I also went with a 24/12-70a converter. Slides working great. Overall performance is better than the WFCO. Consider the 12/24-15 Orion charger. Install the charger under the hood and then run 6awg to the RV’s 24v battery bank ?? 60a circuit resettable breaker @12v. 30a midi fuse on 24v run near battery bank.
 
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