Hello, this is my first post, My bus should use about 900 Amp hours per day, I am wondering suggestions for Inverters, Chargers and other electrical equipment. I want to go full time in my 7-Window Blue-Bird. I am thinking of a 3500-4000 Watt inverter, but I need it to not break the bank. I want to be able to plug in the bus also. Any suggestions will help!
What Inverter/Charger should I use?
- Thread starter FawnaFox
- Start date
Rucker
Senior Member
Welcome!
If you've already done the calculations that get you to that value of 900 it might be helpful to share the list. Your usage will probably have peak times, which determine how large an inverter is needed. What will be the peak usage times, and which devices?
By way of example if you are installing a minisplit for air conditioning, they typically need a minimum of 15-20 amps per hour at 120 volts, so 150-200 amps per hour at 12 volts dc into the inverter (which converts from 12 volts DC to 120 volts a/c). That would be approximately 2400 watts an hour just for the minisplit when in use.
So at peak times if something like a minisplit is running along with water pumps, fans, lights etc. you might be at 3600 watts per hour. For long life, you don't want to max out an inverter, best to keep the usage at some percentage of the inverter capacity, like 80% (you get to decide that percentage, I just use what comes to my mind as reasonable).
That would mean you'd need an inverter rated at about 4500 watts continuous. A quick check online shows the best fix would be a 5,000 watt inverter, using the above calculations.
Looking at that though it seems that if you are able to juggle peak usage you might be able to use a 3,000 watt inverter. That's where usage and strategy (and lifestyle) come into play. Do you really need 900 amps? Or are there changes you could make to your plans for full time that would allow for less usage...
Having said all of that, a 2,400 watt inverter is probably the smallest you could use; but every increment up from that requires heavier wires, fuses, connectors and the cost goes up by factors, not just proportionately. If a wire of a certain gauge costs a buck a foot, a wire twice as thick may cost more than double that: the bigger, the ever more costly.
This is just meant to give you a sense of how you might want to approach the design phase. Great to have you join and even better that you are asking the right questions!
If you've already done the calculations that get you to that value of 900 it might be helpful to share the list. Your usage will probably have peak times, which determine how large an inverter is needed. What will be the peak usage times, and which devices?
By way of example if you are installing a minisplit for air conditioning, they typically need a minimum of 15-20 amps per hour at 120 volts, so 150-200 amps per hour at 12 volts dc into the inverter (which converts from 12 volts DC to 120 volts a/c). That would be approximately 2400 watts an hour just for the minisplit when in use.
So at peak times if something like a minisplit is running along with water pumps, fans, lights etc. you might be at 3600 watts per hour. For long life, you don't want to max out an inverter, best to keep the usage at some percentage of the inverter capacity, like 80% (you get to decide that percentage, I just use what comes to my mind as reasonable).
That would mean you'd need an inverter rated at about 4500 watts continuous. A quick check online shows the best fix would be a 5,000 watt inverter, using the above calculations.
Looking at that though it seems that if you are able to juggle peak usage you might be able to use a 3,000 watt inverter. That's where usage and strategy (and lifestyle) come into play. Do you really need 900 amps? Or are there changes you could make to your plans for full time that would allow for less usage...
Having said all of that, a 2,400 watt inverter is probably the smallest you could use; but every increment up from that requires heavier wires, fuses, connectors and the cost goes up by factors, not just proportionately. If a wire of a certain gauge costs a buck a foot, a wire twice as thick may cost more than double that: the bigger, the ever more costly.
This is just meant to give you a sense of how you might want to approach the design phase. Great to have you join and even better that you are asking the right questions!
Slapdash
Senior Member
My wife and I used Victron components for most of our electrical needs after taking a masterclass on how to put it all together. It was definitely an eye-opener. We juuust finished it and it works great. We used the Victron MultiPlus II for the inverter/charger, and Victron DC to DC, BMS, Battery, solar charger, shunt, Cerbo, etc. I am not sure if I can put the links to the class and the monthly calls here per the rules, but feel free reach out if you want more info.
Rucker has some great info above, particularly with calculating the things you actually need and what will run over time, etc. Also some things like ACs and fridges and the like don't run all the time, just when they need to bring the temps back down/up, etc.
My setup includes shore power, solar, and alternator charging when the bus is running. We have a 5-window mini that's set up for 3-season, so a full size for full-time living is going to be a little different.
Either way, welcome to the asylum!
Rucker has some great info above, particularly with calculating the things you actually need and what will run over time, etc. Also some things like ACs and fridges and the like don't run all the time, just when they need to bring the temps back down/up, etc.
My setup includes shore power, solar, and alternator charging when the bus is running. We have a 5-window mini that's set up for 3-season, so a full size for full-time living is going to be a little different.
Either way, welcome to the asylum!
Thanks for the advice, I have found that I need a minimum of a 3000 watt inverter. My only remaining question is should I use a 120 volt or 240 volt charger?
Your standard RV power pedestal is going to be a 30 amp, 120v service. If you wanted to use 50 amp service (different type of plug), you could go to 240 if you had high power needs (multiple rooftop AC units, etc).
50 amp service is less common, but you can still use the 30 amp pedestals with an adapter plug.
Also, make sure you are purchasing the correct inverter for your planned battery bank (whether it is 12v, 24v, or 48v). They are built for a specific battery bank voltage.
50 amp service is less common, but you can still use the 30 amp pedestals with an adapter plug.
Also, make sure you are purchasing the correct inverter for your planned battery bank (whether it is 12v, 24v, or 48v). They are built for a specific battery bank voltage.
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Is there a charger you would recommend that can handle both 30Amp@120V and 50 Amp@240? I plan to use 3 or 4 batteries in a 12 volt configuration.
Are you wanting to buy an inverter/charge combo (like a Victron multiplus), or are you specifically asking about a standalone charger? To clarify, the 120v vs 240v consideration is one you need to be making for your inverter, so remove the charger from the equation when you are making a decision there based on your power needs for AC circuits.
The inverter/charger combo will provide your AC power regardless of if you are on shore power or running off of batteries. The charger part of the inverter/charger will only charge your battery bank while on shore power. If you are also going to have a solar array that you want to charge your batteries, you will additionally need an MPPT solar charge controller.
I think there are some offerings that do an all in one type thing (EG4) but I do not have experience with those. I use Victron.
The inverter/charger combo will provide your AC power regardless of if you are on shore power or running off of batteries. The charger part of the inverter/charger will only charge your battery bank while on shore power. If you are also going to have a solar array that you want to charge your batteries, you will additionally need an MPPT solar charge controller.
I think there are some offerings that do an all in one type thing (EG4) but I do not have experience with those. I use Victron.
I think the combo would be good, I don't plan on installing solar as I would rather have a full length roof deck. Basically I want to be able to charge with shore power and alternator power. I also will only be using 120 volt for the bus AC (I will have no 240 inside the bus). Will the multiplus also charge via the alternator? (I will be installing a more powerful alternator, as the current one is not powerful enough.)
Rucker
Senior Member
If your usage is 900 amps per day, your battery capacity needs to be greater. I'm guessing you know that.
Slapdash
Senior Member
Wish I could help there. I stuck with 120, just because I am familiar with 12V and 120, which I look at as 'car and house'. Once I hit 24/48 and 240, I lose consciousness. 
Yeah, this is also a good point in that there are minimum battery bank sizes required depending on inverter size and battery chemistry. How many you need will depend on the capacity (amp hours) of the particular type of 12v battery you are buying. Are these going to be lead-acid or LFP batteries? Lead-acid can only discharge about 50% of their capacity so it will take almost twice the number of lead-acid than LFP assuming they are rated for the same Ah.
Also, I highly recommend checking out this youtube channel. They are great for off-grid electrical knowledge.
EXPLORIST life Mobile Marine & Off-Grid Electrical
EXPLORIST.life’s mission is to provide the most complete and easily understandable mobile, marine, and off-grid electrical education for beginners, aspiring professionals, and professionals to gain actionable skills to design and install electrical systems for vans, RVs, skoolies, expeditions...
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heimlich
2003 International 3800 T444E
I installed an All-in-one. It was so loud I took it out and sent it back. If you have the inverter/charger/MPPT inside the but and you dislike this type of noise keep this in mind.
nikitis
1994 International 3800 - Thomas, T444E 165HP
If going with 12v battery bank, be sure your 3000 watt inverter is a 12v. Configuration.
Which one did you have? I’m currently looking at the Eg4 or growatt 3kw all in ones.
heimlich
2003 International 3800 T444E
I had the yellow 3kw EG4 but I've read they are all the same. I switched out everything for Victron. It's more expensive but I got rid of all the fan noises except for the inverter. That one only comes on when I run the minisplit.
Dang, good to know that’s exactly what I was going to get. Rethinking that now.
heimlich
2003 International 3800 T444E
You should easily be able to find everything that doesn't have a fan on it. The inverter is the hard one. There aren't many choices for ones without an internal fan.
fo4imtippin
Senior Member
I have a 12kpv. Fan doesn't turn on unless load or PV is above 6k. The 6000xp and yellow 3k have way smaller heatsinks and need the cooling.
heimlich
2003 International 3800 T444E
I plugged in the solar array to the 3k unit and the fan came on. I switch the power on from shore and another fan came on. I turned on an AC unit and another fan came on. All I did was turn these things on and the fans came on in the unit. I don't know how your larger unit works but this was my experience. Thankfully when I purchased the unit I asked Signature Solar if fans would come on and was told no. When the fans did come on they took the unit back.
Yeah I'm constantly putting fanless equipment into vans other than the victron inverter, but really liked the idea of an all in one.
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