Another RV thread

[mmmmmdonuts]

I have upgraded my travel trailer to a larger 38' travel trailer (2x ACs now) with a 50 amp service vs the 30 amp service I had in the past.

In my old TT I had a manual transfer switch, 2x 12V batteries lithium, a 3KW inverter and a spare 12V battery charger that charged the lithium ion battery. I also had a DCDC 12V charger from my truck to the trailer.

Recently I picked up 2 more batteries and 5 solar 295W solar panels that I hope to use to alleviate the use for generators. I also already have a 50A transfer switch ready to go.

My question is has to do with the best way to integrate solar and how I should do things. Looking at the solar controllers independently I would need 3 of these Victron MPPT at $180 a pop. Basically for $560 I am pretty close to getting a growatt or some other 24v or 48v all in one inverter that is way more powerful than what I have. Should I reconfigure the system for 24V or 48V instead? Possibly upgrade to a 5kw inverter?

Basically since I have no 240V loads currently just wire it in with the transfer switch? Or put in a separate breaker box to take only one of the legs to the AIO? It would be a whole lot simpler to wire in my opinion.

24V or 48V as well? 48V has way more options but 24V allows me to operate with a battery failure. I could also keep the 12V battery that the RV already has or use a step down converter.

Thanks in advance. Thoughts?

 

[justinm001]

Why not get a larger mppt or 2?

 

[mmmmmdonuts]

Why not get a larger mppt or 2?

The price above 50/60amp MPPT gets very expensive quickly into the $400+ range. Basically it looks like I will be at $500+ already and the AIO allow higher voltages. Basically 12V at 1500W is a lot of current.

 

[time2roll]

This system deserves to be at 24/48 volts.

 

[12vDC]

Do the 48V AIO with a stepdown. Would seem simpler for the solar as well.

Which battery(s) are you planning to use?

Do you have a diagram to share? If not, it should help you determine what is easiest and/or better for the long run.

 

[eXodus]

24V or 48V as well? 48V has way more options but 24V allows me to operate with a battery failure. I could also keep the 12V battery that the RV already has or use a step down converter.

I have a 24V system - this voltage is slowly dying, not many new products are coming out.

These days I would go 48V. You didn't say what batteries you are using? And it is very likely in the long run that you are going to have more batteries then you have today.

 

[mmmmmdonuts]

Sorry for the quick hand drawing. Basically what I currently would have is you substitute the AIO with separate chargers and inverter and MPPT connecting to the battery bank. Right now my batteries are 4x TimeUSB 100AH 12V batteries. Not sure how well they will do in series charge but I would balance them before hand accordingly to the instructions and over the winter I take the batteries in and would charge them individually. Still contemplating if series makes the most sense or parallel since I do a lot of camping in the woods with partial sunshine.

 

[chrisski]

If the constant load is 2000 watts or less, I would go with 24 volts. Greater, 48 volts. Really depends on running one or two high wattage items.


Personally, I prefer the 24 volts because of the accessories available and already installed equipment. Dual 12/24 LEDs, QC, power supply for my tire minder, available quality 50 amp+ DC to DC step down converters, choice of 15 amp 120 AC to 24 VDC step converters, rating of equipment already in my trailer, and a couple other things. Many items I already had were not rated above 24 volts: fuses, 3 X MPPTs, switches, etc.

If you’re just running one high wattage AC load at once, 24 VDC is fine. If you turn on two ACs, or one AC and the water heater, then this will push the needs up to 48 VDC,

 

[eXodus]

The Growatt (or all AIO) have a integrated transfer switch. I put the Inverter before the RVs subpanel.

The cord external to the RV goes directly into the AIO. This is my system from 2 years ago, just a few minor changes - have a 30A breaker for the panels and LFP for the 12V side as well now.

 

[mmmmmdonuts]

So the one difference is I got be able to hand a 240V input or a 120V input. That is why I was debating on putting the transfer switch in. As far as power is concerned I probably am about 1 AC based on the battery just due to the simple fact I think I will kill the battery too quickly otherwise. I do in fact have 2 ACs in the trailer though. I try and get away with fans whenever I can vs AC and just suffer overnight. I am in the northeast so in general it isn't as bad as it would be south and west. I do like the fact of the ability to use a lot of my stuff I already have for 24V vs 48V but it is mainly fuses or small circuit breakers. I would need a new DC to DC regardless. I also like the redundant factor built in to the 24V system. I do worry about the 3KW starting my AC though.

 

[justinm001]

Easystart on the acs will help with the low power. Victron makes a 2x120 which does both 120 and 240v inputs. You also can just use 1 leg of the 50a it's still 6kw (4800w over 3 hrs) this seems ideal with Victron inverters as they have assist so you get the 4800w plus 3000w to start and run acs, microwave and such then when you dip under 4800w it recharges batteries. But 50a breakers at CGs seem to blow well below 50a, below 40 I've noticed.

You have 2 acs you can use the front one during the day then the back one at night. Use them both with the genny to cool down then just the 1 in the room you're in to keep it cool. I have 6 ACs and we routinely switch from front to middle to back. #4 is vented in the bedroom, bathroom and front so we use that when sleeping as it's silent and still powerful enough to keep it cool. Depending on how yours is ducted it might make sense to run ac on one then just fan on 2nd.

 

[mmmmmdonuts]

Thank you for all the advice. I need to do more research on this too on the AIO.

I just wanted to make sure it makes sense from a cost perspective to look at an AIO with MPPT vs just getting two or three separate controllers. It seems like the consensus is a yes.

Any thoughts on what to do with he other hardware I have other than sell it?

 

[chrisski]

do worry about the 3KW starting my AC though.

My 3 kW Samlex PST 24 volt inverter with an Easy Start turns on a 15 k BTU unit with no issues. I installed the easy start prior to the 3 kW upgrade, so I don’t even know if the inverter needed that or not.

So the one difference is I got be able to hand a 240V input or a 120V input.

Do you use 240 volt power in an RV? Although possible, this is extremely rare.

The 240 volt input for the RV is is split phase power, two 120 volt legs. Each of the 120 volt legs goes to a seperate leg and never combines to 240 volts.

In my case, I saw no need for the 240 volts. A 3 kW inverter is a little less power than a 30 amp RV hookup, which is a single 30 amp leg that gets jumpered and sent to both legs of the RVs circuit breaker box.

Also in my case, I opted not to install a transfer switch and if I use shore power, or hook a generator up, I disconnect the Inverter plug from the shore power jack and hook up shore power. For the RV plug, I wired a 50 amp RV plug by jumper ing the two phases together.

 

[chrisski]

I just wanted to make sure it makes sense from a cost perspective to look at an AIO

I opted not to do the AIO in part because they tend to charge through the charger or MPPT, not both.

With seperate components, on a cloudy day, I plug in the generator or plug in the shore power, and that charges the battery, and whatever power the sun can provide, that hekps charge the batteries.

With that method, just need to be sure AC-> DC converter charging + Solar Charging does not exceed limits of wiring and fuses.

 

[eXodus]

I opted not to do the AIO in part because they tend to charge through the charger or MPPT, not both.

nope, my Growatt charges from the Charger and MPPT at the same time.

It can not invert and charge at the same time. It uses the same circuit in reverse.

When you are on the grid/generator charging - all appliances run from the grid/generator.

When you use the batteries - you can not charge from the grid only from the MPPT.

 

[eXodus]

Easystart on the acs will help with the low power.

my 3000W AIO does fine with my single A/C and a hard-start kit.

These days I would upgrade to 48V or 120V Inverter A/C unit.

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[chrisski]

nope, my Growatt charges from the Charger and MPPT at the same time.

I recommend reading the manual of the units to install. Works for you. Does not work for me.

An Outback Radian will not use full input from the MPPT and the charger at the same time. My Victron MPPTs and the Aims AC to DC converter will.

 

[Dooug]

Going to 48 volts forces a high voltage series string for solar. This can be challenging for some RVs due to panel placement and shading issues. if you park in big open areas and have an easy roof to mount panels then it should work. In the pacific northwest this could be a challenge...arizona not so much.

24 volt bridges the gap well and supports easier down conversion to 12 volts. Its a shame there is not more 24v stuff coming out. Truck campers suit this need well with minimal roof space.

 

[justinm001]

my 3000W AIO does fine with my single A/C and a hard-start kit.

These days I would upgrade to 48V or 120V Inverter A/C unit.

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my 3000W AIO does fine with my single A/C and a hard-start kit.

These days I would upgrade to 48V or 120V Inverter A/C unit.

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Note: Smartphone connectivity is only available on the free blow variant. Unprecedented 2 year Replacement Warranty Why Choose us ECO-COOL is built for any extreme climate condition SLEEK AERODYNAMIC DESIGN ECO-COOL is everything you want in an AC system when making that buying decision for...

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Wow first inverter type I've seen thats standard mount. I haven't seen a 48v that does 15k btu.

The LRA on my 15k Dometic is like 57amps. I think the 13k is 52a and idk the furrion 15.5k but they say they have a soft start yet struggles with my 5000w inverter, the voltage drops on 12v side with 4/0 wiring. No issues whatsoever running 3+ acs at same time on my 48v system

 

[chrisski]

No issues whatsoever running 3+ acs at same time on my 48v system

How many watts from the inverter and also batteries does running 3 ACs pull?

For me and the 24 volt 3000 watt Samlex inverter, starts fine,

My 15 k BTU pulls 1400 watts from the inverter but with inverter losses, close to 1700 watts from the battery.

Two ACs would pull 3400 watts continuous from the batteries, and that is 48 volt territory.