Questions regarding 48v work from home camper setup

[John Frum]

@JoeInNV does your 5th wheel have slides and/or jacks?

 

[JoeInNV]

@JoeInNV does your 5th wheel have slides and/or jacks?

Yes it has 2 slides and jacks

 

[John Frum]

Yes it has 2 slides and jacks

Are they fused at the dc distribution panel?
The dc distribution panel is the fused circuits to the right of the breakers in the combo panel.
Unfortunately they don't appear to be mapped.

 

[Tomthumb62]

Combining 2 batteries to make 24 volts nominal makes the batteries prone to voltage drift, its even worse with 48 volts.

How do you accommodate or balance this voltage drift? Or do you avoid it by not putting batteries in series to get 24v and just buy 24v batteries to begin with?

 

[John Frum]

How do you accommodate or balance this voltage drift? Or do you avoid it by not putting batteries in series to get 24v and just buy 24v batteries to begin with?

Ideally I prefer batteries at system voltage.
This is an option.

Battery Balancer - Victron Energy

Equalize the state of charge of two series connected 12V batteries using the Battery Balancer. Find a Victron Energy dealer near you.

www.victronenergy.com

 

[JoeInNV]

The panels can be put in series to make higher voltage strings.
Combining 2 batteries to make 24 volts nominal makes the batteries prone to voltage drift, its even worse with 48 volts.
I think you should be starting out with a 48 volt system.
That means 48 volt batteries and a 48 volt AIO.
Maybe even a 48 volt dc to dc converter for the RV.

Hmm, 48v AIO MPP LV6048 - $1,555
Will's recommended 48v SOK batteries are $1,789.99 each...how many of those would I need? Could I get away with just 1 to start out with? If I need more than one, I don't think I can afford a 48v setup right now.

 

[John Frum]

Hmm, 48v AIO MPP LV6048 - $1,555
Will's recommended 48v SOK batteries are $1,789.99 each...how many of those would I need? Could I get away with just 1 to start out with? If I need more than one, I don't think I can afford a 48v setup right now.

You could, but the self discharge rate of those inverters is really high.
You would use nearly half of your battery each day just have the inverter on.

 

[ianganderton]

Without doing a power audit you are going to waste a rack of cash on a system that won’t be fit for purpose

Part of the reason for doing a power audit is so a better understanding of what’s involved is gained. It’s the foundation for everythjng

If you find the power audit a bit challenging wait till you get further into it without this key foundation knowledge!!!! ?

Missing out key steps is the best way to waste cash AND end up with a system that doesn’t work as intended

 

[JoeInNV]

You could, but the self discharge rate of those inverters is really high.
You would use nearly half of your battery each day just have the inverter on.

Dang ok so you would recommend at least 2 to start?

Does one 48v battery have more storage capacity than one 12v battery?

 

[JoeInNV]

Without doing a power audit you are going to waste a rack of cash on a system that won’t be fit for purpose

Part of the reason for doing a power audit is so a better understanding of what’s involved is gained. It’s the foundation for everythjng

If you find the power audit a bit challenging wait till you get further into it without this key foundation knowledge!!!! ?

Missing out key steps is the best way to waste cash AND end up with a system that doesn’t work as intended

Thanks for this info Ian! Maybe if I explain my situation a little you might understand why I seem to want to charge ahead without worrying so much about the power audit. I'm currently in a month to month lease, and I pay 1k/month in rent. My work from home job is a contract role that's scheduled to end in May. After paying rent, I have about 2k in remaining income each month from my paychecks. I have a 10 acre parcel of land with a well already drilled, and I want to stop paying rent and move onto my land ASAP. So the way I figure it, I could stay in my rental for the winter and move onto my land in March, during which time I would save an additional 6-7k, and would pay an additional 4k in monthly rent. Or I could move onto my land at the end of November, not pay any more rent, and have about 3k in monthly income until my job ends in May. The way I'm looking at it, I only have about 6 months of certain income left...so I'd rather use 4k of that money toward solar improvements if my initial system falls short, rather than giving it to my landlord in rent.

 

[ianganderton]

Thanks for this info Ian! Maybe if I explain my situation a little you might understand why I seem to want to charge ahead without worrying so much about the power audit. I'm currently in a month to month lease, and I pay 1k/month in rent. My work from home job is a contract role that's scheduled to end in May. After paying rent, I have about 2k in remaining income each month from my paychecks. I have a 10 acre parcel of land with a well already drilled, and I want to stop paying rent and move onto my land ASAP. So the way I figure it, I could stay in my rental for the winter and move onto my land in March, during which time I would save an additional 6-7k, and would pay an additional 4k in monthly rent. Or I could move onto my land at the end of November, not pay any more rent, and have about 3k in monthly income until my job ends in May. The way I'm looking at it, I only have about 6 months of certain income left...so I'd rather use 4k of that money toward solar improvements if my initial system falls short, rather than giving it to my landlord in rent.

Understand but an audit is a way of saving money!! Doesn’t cost anything but a bit of time and gains/saves you loads

I can see from your answers and questing a already you would massively be if it from the process

But hey, your choice!

 

[JoeInNV]

Understand but an audit is a way of saving money!! Doesn’t cost anything but a bit of time and gains/saves you loads

I can see from your answers and questing a already you would massively be if it from the process

But hey, your choice!

As far as saving money, I think I'll save the most money by not paying any more rent ASAP. If the solar system I start with doesn't end up meeting my needs, I'm sure I'll be able to put it to use somewhere else on the property at some point. I appreciate your input, I realize what I'm asking may not be typical. But everyone has been very helpful so far and I truly appreciate everyone's time and consideration!

 

[ianganderton]

I realize what I'm asking may not be typical.

unfortunately it is quite typical, folks hate doing the planning but invariably live to regret it

 

[John Frum]

Dang ok so you would recommend at least 2 to start?

After having read more about your situation I will have to think about it more.

Does one 48v battery have more storage capacity than one 12v battery?

The best way to compare battery capacity across voltages is using watt hours.
watt hours = voltage * amp hours

The 48 volt sok battery is 100 amp hours.
51.2 volts * 100 amp hours is 5120 watt hours
12.8 volts * 100 amp hours is 1280 watt hours

A 12 volt battery has 4 cells in series each with a nominal voltage of 3.2 volts
A 24 volt battery has 8 cells in series each with a nominal voltage of 3.2 volts
A 48 volt battery has 16 cells in series each with a nominal voltage of 3.2 volts

 

[Nevadablue]

I would like to ask a few questions.
You said you have land and a well. Is there grid power to the well? If so, why not spend the winter living in the camper (lots of people do that) and learn more about your requirements for solar. The solar power isn’t required to live in and work from the camper.
What is your internet connection? Phone?
It seems a shame to hurry the solar install when it doesn’t seem necessary for you at this point in time. Learn more then do.

 

[JoeInNV]

After having read more about your situation I will have to think about it more.

The best way to compare battery capacity across voltages is using watt hours.
watt hours = voltage * amp hours

The 48 volt sok battery is 100 amp hours.
51.2 volts * 100 amp hours is 5120 watt hours
12.8 volts * 100 amp hours is 1280 watt hours

A 12 volt battery has 4 cells in series each with a nominal voltage of 3.2 volts
A 24 volt battery has 8 cells in series each with a nominal voltage of 3.2 volts
A 48 volt battery has 16 cells in series each with a nominal voltage of 3.2 volts

Thank you for explaining this so clearly!

So a 48v battery has four times as much "juice" as a 12v...but the 48v MPP eats half of it every day just being on, not even powering anything? Wow.

 

[JoeInNV]

I would like to ask a few questions.
You said you have land and a well. Is there grid power to the well? If so, why not spend the winter living in the camper (lots of people do that) and learn more about your requirements for solar. The solar power isn’t required to live in and work from the camper.
What is your internet connection? Phone?
It seems a shame to hurry the solar install when it doesn’t seem necessary for you at this point in time. Learn more then do.

Hey there fellow Nevadan,


No, no grid power at all to the parcel. Internet is a dish, it uses line of sight to a nearby mountain antenna.

I need to be able to continue my job, which requires internet. Rather than run a gas generator for 4 months, or rent for 4 more months, I wanted to get on my land and try a bare bones solar setup. To be able to do my job, I truly only need to power the internet dish and my laptop for 8-9 hours M-F. I agree having more time would be ideal, but that's why I think an all in one MPP box would be a perfect solution for my situation. Less for a beginner to mess up.

 

[Rednecktek]

Thank you for explaining this so clearly!

So a 48v battery has four times as much "juice" as a 12v...but the 48v MPP eats half of it every day just being on, not even powering anything? Wow.

Yeah, that's the big downside to AIO's. Because they have so many things going on inside and each internal piece is designed to be cheap rather than efficient, each piece uses a bit of standby current. A 3Kw AIO inverter is usually about 60-ish watts per hour to exist and be running. The 6048 version is really just two of their 3048 units (3000w, 48v = 3048 for naming convention) slapped together inside the same box. So, if each unit is pulling 60w an hour to exist, and you've got 2 units, that's 120w per hour just to feed the inverter. In a 24 hour day that's 120 * 24 = 2880 watt hours of battery to exist.

So there are three ways of dealing with this problem:

1: Use a smaller AIO that doesn't draw as much power and limit your usage, like just using the single 3048 for 60w/hr
2: Spend a fortune on Tier-1 Super efficient components that you assemble yourself to save standby power and skip the AIO
3: Spend more money on another battery

The EG4's are about $1500 right now and I think are the best bang for the buck rackmount batteries out there. That's 5Kwh of battery of which you'll lose about half to inverter standby, but you'd have to compare the $1500 for a second battery VS the cost of all the Tier-1 parts that might save you half your standby draw or less.

So here's an idea. Since you're looking at the MPP units anyways, start out with a 3048 alone and a single rackmount battery or two. Have your electrician friend install a 30a AND a 50a plug into the side of the container and either have him do the jumper thing or just get the off-the-shelf adapter. Then, in the future get another 3048 and the communications cable and install it right next to the existing one to give you that 50a 240v socket. Move the plug and be done with it. If you find you need more than the 30a per leg that gives you, you can always add more 3048's in parallel to increase your power availability, but I doubt you're going to need to if you're a bit wise about your power usage.

Or go for the gold and get a second battery and a 6048, park your container so you have a long side facing south, build a frame on top of the container and start loading it up with all the panels you can use up there. With a 40' container and careful panel choice you might be able to squeeze 4Kw worth up on the roof. It's a lot up front BUT that's super simple and should last many, many years of feeding a camper when you rent it out to the in-laws.

As to feeding the well pump, that's a whole 'nother can of worms. If it's shallow enough you might be able to feed it from the 6048 you've already got going OR you'll have to set up another smaller system designed to just feed the well pump. It can be done but it's not super cheap because most well pumps have HUGE startup draws and your Low Frequency inverters are pricy! I've looked at building a solar backup for my well pump and I think I can make something that will barely work for about $2000 as long as I don't need to run it for more than an hour a day or so. But then again, my pump is 300ft deep.

 

[John Frum]

Hey there fellow Nevadan,


No, no grid power at all to the parcel. Internet is a dish, it uses line of sight to a nearby mountain antenna.

I need to be able to continue my job, which requires internet. Rather than run a gas generator for 4 months, or rent for 4 more months, I wanted to get on my land and try a bare bones solar setup. To be able to do my job, I truly only need to power the internet dish and my laptop for 8-9 hours M-F. I agree having more time would be ideal, but that's why I think an all in one MPP box would be a perfect solution for my situation. Less for a beginner to mess up.

You also need to keep your fridge running.
You will need to cook as well.
Suggest propane for the latter.

 

[JoeInNV]

Yeah, that's the big downside to AIO's. Because they have so many things going on inside and each internal piece is designed to be cheap rather than efficient, each piece uses a bit of standby current. A 3Kw AIO inverter is usually about 60-ish watts per hour to exist and be running. The 6048 version is really just two of their 3048 units (3000w, 48v = 3048 for naming convention) slapped together inside the same box. So, if each unit is pulling 60w an hour to exist, and you've got 2 units, that's 120w per hour just to feed the inverter. In a 24 hour day that's 120 * 24 = 2880 watt hours of battery to exist.

So there are three ways of dealing with this problem:

1: Use a smaller AIO that doesn't draw as much power and limit your usage, like just using the single 3048 for 60w/hr
2: Spend a fortune on Tier-1 Super efficient components that you assemble yourself to save standby power and skip the AIO
3: Spend more money on another battery

The EG4's are about $1500 right now and I think are the best bang for the buck rackmount batteries out there. That's 5Kwh of battery of which you'll lose about half to inverter standby, but you'd have to compare the $1500 for a second battery VS the cost of all the Tier-1 parts that might save you half your standby draw or less.

So here's an idea. Since you're looking at the MPP units anyways, start out with a 3048 alone and a single rackmount battery or two. Have your electrician friend install a 30a AND a 50a plug into the side of the container and either have him do the jumper thing or just get the off-the-shelf adapter. Then, in the future get another 3048 and the communications cable and install it right next to the existing one to give you that 50a 240v socket. Move the plug and be done with it. If you find you need more than the 30a per leg that gives you, you can always add more 3048's in parallel to increase your power availability, but I doubt you're going to need to if you're a bit wise about your power usage.

I like the way you think dude