Sorry for the long post in advanced. Newbie here. I'm attempting to plan a split phase 50amp rv build. The rv runs off mostly 12vdc with 50a split phase shore power. I plan on using 2 victron inverters and equipment to power new system. The question I have is running it on 12v or 24v or 48v (can you run 2 inverters on 12v)? As of right now my 12v loads are constant 50 to 60 amps with a need for a surge to about 150a when running the jacks and slides, for only a few minutes. On the ac side I would like to be able to run 2 13k airconditioners and various other things. The problem I'm having is if I use the higher voltages I have to convert back to 12v at 160amps or have a separate 12v battery with separate charging of about 70amps to cover my loads which adds complexity, inefficiency and money. I understand cable sizing for using higher voltage but converting back and forth voltage is also a problem. Also which inverters should I use multiplus2 2x120 3000va or a multiplu 2 5000va if using 48v? Thankyou for your input.
Rv solar design questions?
- Thread starter stevbross
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Either go 12v or 48v.
When an air conditioner has a Micro aire EZ start it will run off a Victron 12/3000 inverter. The problem is how long…
I have a 544ah 12v lithium battery and can run the air conditioner for about one hour - then I either need to stop or start the generator. (On a full battery to start with and some solar - that will leave me enough power to get through the night). So you will need a massive battery bank to run them for any length of time.
If you go with 12v - look at the Multiplus II 12/3000 2x120v - (unless you have something that is 240v). You would put two in parallel. Then if you are not needing both air conditioners, you have the option of changing the configuration and turning the second one off to save watts.
Good Luck
When an air conditioner has a Micro aire EZ start it will run off a Victron 12/3000 inverter. The problem is how long…
I have a 544ah 12v lithium battery and can run the air conditioner for about one hour - then I either need to stop or start the generator. (On a full battery to start with and some solar - that will leave me enough power to get through the night). So you will need a massive battery bank to run them for any length of time.
If you go with 12v - look at the Multiplus II 12/3000 2x120v - (unless you have something that is 240v). You would put two in parallel. Then if you are not needing both air conditioners, you have the option of changing the configuration and turning the second one off to save watts.
Good Luck
You tell us what you are wanting to do, but very little about the RV itself, and how you plan to use it. You say right now your current 12V loads are a constant 50-60 amps, I have to wonder why? I have a 28 ft Class A motorhome, (which I suspect is smaller than your RV as you say you have 3 air conditioners), in my case the leveling jacks are powered by the 12V engine starting batteries, not the house battery, and my typical 12V load not counting the inverter is more in the neighborhood of 20-25 amps, with my highest amp draw appliance being the Suburban SF42F furnace at around 10 amps, followed by the control circuits for me air conditioner, refrigerator and water heater totaling around another 4 amps, various LED lights at all on at once perhaps another 10 amps, water pump is about 8 amps, but it is not constant load, about all that is left are USB charging ports, which may be another 5-10 amps max if all were in use and maxed out at once.
sunshine_eggo
Happy Breffast!
If you are doing a DIY install, when you configure the inverters in split phase, you must disable "switch as group" to be able to pass through and charge with 120V (30A) shore power. It is also important that you supply ONLY one inverter with the 120VAC power. Default behavior with 50A RV on 30A shore is to jump L1 to L2 to provide 120VAC to both halves of the 50A panel. A custom 30-50A adapter that only connects to L1 would work.
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I have not seen such jumping as you describe in 50A RV panels, only in 30 to 50 amp RV adapter power cords, or in RV transfer switches to allow a 120V generator to provide power to both sides of a 50A RV breaker panel, while providing 120/240 split phase to the panel when plugged into a 50 amp RV outlet.
sunshine_eggo
Happy Breffast!
I was speaking in the context of 120VAC, but I've edited for clarity.
justinm001
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Why do you want 2 inverters? Do you have 240v loads? 2 ACs running will be close to the 3kva where you'll have plenty of room with 5kva or twin 3kva. Either you'd still need easystarts and would stagger start them.
Mp2x120 is a special inverter, it'll pull 50a/240v and pump out the 240v when hooked to shore then both 120v when inverting. If you have a generator the Quattros are the best, although you need 2 if you want to pull all the power from shore but 50a 120v is 6kw and if you have 5kw inverter you have quite a bunch of power.
48v is ideal and you can just convert 48/12 with 1 or more orions (only 400w) although 24/12 can do 70-85a. You're not going to run the slides and jacks at same time but even then a couple orions will do it.
Mp2x120 is a special inverter, it'll pull 50a/240v and pump out the 240v when hooked to shore then both 120v when inverting. If you have a generator the Quattros are the best, although you need 2 if you want to pull all the power from shore but 50a 120v is 6kw and if you have 5kw inverter you have quite a bunch of power.
48v is ideal and you can just convert 48/12 with 1 or more orions (only 400w) although 24/12 can do 70-85a. You're not going to run the slides and jacks at same time but even then a couple orions will do it.
justinm001
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This is spot on, although I've found a 15 to 50a adapter which doesn't have the issue and works perfectly.... using it now actually. Still looking for a 30 to 50 (ss2-50r) which isn't jumped. Don't want to mess up a sealed cable.
Although I don't really see the point in op putting in split phase over parallel if only 3k inverters since it only allows 3kva on each leg so running both acs (one on each) he can't run the microwave or another large load, but if parallel he'd have 6kva and can all of it.
I have a 5th wheel with 3 13k airconditioners the load is estimated for winter camping where you would have furnace, tank heaters, battery heaters, fridge and lights. In the future I may put In a 240v mini split but it is not a fore gone decision. If using the multiplus it should just be a programing change to operate in parallel or split phase when the time comes for that change. I do plan on building in stages though. I have installed a victron shunt and a cerbo for monitoring already, and came up with the ballpark values estimating the tank heaters since it was not cold enough for them to operate. The hydraulic pump for the slides and jacks takes a lot of power hence the 150a at the time of use. I plan on building my own battery and adding a large solar system but just trying to figure out the right voltage. With a 12v system I don't need any conversion just larger wires, 24v system i would need to convert back to 12 for dc loads and still use same size wire as 12v, with 48v smaller wires but converting back to 12v a lot harder.
justinm001
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Yes just a programming change using the mk2 cable to switch to split phase. Although I'd assume rewiring is needed.
Pumping 3kw at 12v is 250a which is right at the 4/0 limit and if you have 2 of them that means 2 4/0 wires and terminals that can handle them. Building a battery to handle 500a draw is going to be rough. And this isn't including the surge of ACs even with easy starts.
I have a 5kw quattro on my 12v system and with 4/0 cabling and lynx shunt/block I still needed to lower my shut off voltage because it would trip the AC when easy start would try to run. With my twin quattros 5k 48v in split phase I haven't had any issues and it's programmed to run 4 additional acs without easy starts
Pumping 3kw at 12v is 250a which is right at the 4/0 limit and if you have 2 of them that means 2 4/0 wires and terminals that can handle them. Building a battery to handle 500a draw is going to be rough. And this isn't including the surge of ACs even with easy starts.
I have a 5kw quattro on my 12v system and with 4/0 cabling and lynx shunt/block I still needed to lower my shut off voltage because it would trip the AC when easy start would try to run. With my twin quattros 5k 48v in split phase I haven't had any issues and it's programmed to run 4 additional acs without easy starts
