Crown Bus conversion Battery backup

[Rawlings]

Okay guys, we have begun our build and I have setup our 30amp panel. I am starting to draw out plans. Initially we didn't want to invest in a battery system since we don't have the funds to pull enough solar energy to charge it. But now we are figuring out refrigerators. We are not going to be living in the bus full time but we will take it out for 1-2 months at a time each year and trips in between. We want a fridge that is at least 7CU Ft. I have seen many that are Gas, 120, and 12 volt. I am sort of shying away from gas fridge just because that will require drilling holes on the side of the bus or top for ventilation. We will be going to camps with 30/50amp service but we do want to be off grid some days. What sort of battery backup do I need to setup to keep a fridge alive for at least a few days (2-3 days)until I can plug in and charge batteries back up or how much solar panels would I need to keep them topped off so that a fridge this size can run indefinitely.

We are planning to do a Pioneer Mini Split AC. We don't use many appliances at once, we don't sit in the bus for hours and watch tv or any of that. We have laptops that last 5-7 hours and hotpots that run almost 10 hours on battery power so the only things I am really concerned about are Fridge and having a few hours of AC a day.

Type of fridge wanted (this might be a little too big) (Someone in blog said 160 watts and 1.5amps for this fridge)
https://www.homedepot.com/p/Magic-Ch...00WE/302245066

Pioneer Mini Split (Watts 960 for cooling, 1120watts for heating)
https://www.pioneerminisplit.com/col...ystem-full-set

I am thinking 4 100amp hour batteries 12 volt that gives me 400amp hours

That gives me 4800 watts but discharge only to 40% that gives me 2880 watts.

Fridge 160watts 24/hr = 3840
AC system 5 hours = 5 hours = 4800 watts

Am I doing this math right? That means I would need 9000 watts in a day to keep fridge running all day and AC system allowed to run for 5 hours throughout the day.

Any input would be greatly appreciated again we are mostly concerned for AC, we don't plan to be inside bus other than during rain or nights we are big hikers and campers and would be out most day on hikes or outside.

Solar panels, could I do with 800 watts in solar panels, how long would that take to charge? Can Solar panels charge battery bank while batteries are being used by Inverter feeding AC panel.

[john61ct]

The term backup does not really fit, cycling the batteries are part of normal living off-grid. With aircon, you will also need a genset, ideally small and quiet like the Honda EU2200i, can be paired if needed.

Lots of solar will help reduce its runtime. As will very efficient 12/24V fridges, and only cooling a small well-insulated section with aircon.

A little solar is required to get a lead bank back to 100% Full, needed a few times per week for longevity.

Running even a small aircon off batteries need to add 100AH per hour desired, better to just start the gennie.

[Rawlings]

Originally Posted by john61ct

The term backup does not really fit, cycling the batteries are part of normal living off-grid. With aircon, you will also need a genset, ideally small and quiet like the Honda EU2200i, can be paired if needed.

Lots of solar will help reduce its runtime. As will very efficient 12/24V fridges, and only cooling a small well-insulated section with aircon.

A little solar is required to get a lead bank back to 100% Full, needed a few times per week for longevity.

Running even a small aircon off batteries need to add 100AH per hour desired, better to just start the gennie.

Sorry for the bad term. So are you saying it isn't really possible to run a fridge full time on batteries either 12v fridge or a 120v fridge being fed by an inverter tied to batteries?

The AC we would only need a few hours but we can toughen it out most of the time since we are used to camping tents and as we said we hike most of the days we are on trips.

I looked at getting those 6v golf cart batteries and tying them in series and parallel to make 12 volt system. If we are just keeping the fridge on all day a 160watt draw fridge would mean about total 3840 watts. Does this mean it can't be done with just batteries and some panels to keep them from discharging as quickly?

[john61ct]

Everything is Ah per day input vs consumption, watts ratings aren't so relevant.

An Ah counting meter on an appliance per 24 hours will tell the real story.

A fridge is fine, tiny fraction of what aircon demands. But if no genset, will want good efficiency, maybe 30-50 Ah per day, means a 200-400Ah bank, pretty small.

A bus has enough room for lots of solar, but enough for aircon is **huge**, and wouldn't it be nice to be able to park in the shade?

And tripling the battery bank gets bulky, heavy, pricey and will need replacing every few years.

Can be done, but IMO impractical compared to running a little gennie when you want aircon.

Also lets you add more solar incrementally rather than spending thousands on just that piece up front.

[Rawlings]

Originally Posted by john61ct

Everything is Ah per day input vs consumption, watts ratings aren't so relevant.

An Ah counting meter on an appliance per 24 hours will tell the real story.

A fridge is fine, tiny fraction of what aircon demands. But if no genset, will want good efficiency, maybe 30-50 Ah per day, means a 200-400Ah bank, pretty small.

A bus has enough room for lots of solar, but enough for aircon is **huge**, and wouldn't it be nice to be able to park in the shade?

And tripling the battery bank gets bulky, heavy, pricey and will need replacing every few years.

Can be done, but IMO impractical compared to running a little gennie when you want aircon.

Also lets you add more solar incrementally rather than spending thousands on just that piece up front.

I see, okay so what you recommend is a battery bank large enough to keep fridge on for a few hours and have only a couple solar panels to charge that bank. Meaning smaller investment up front which I can increase any time more is needed.

So I can get something like 3 pairs of 6v batteries and a few panels. Then keep a generator that isn't loud like a 2000 watt? Would that be sufficient to power the mini split and fridge? Any generator under $1,000 that isn't loud?

[weboughtabus]

Originally Posted by Rawlings

Then keep a generator that isn't loud like a 2000 watt? Would that be sufficient to power the mini split and fridge? Any generator under $1,000 that isn't loud?

I've been keeping an eye on these Champion Inverter Dual Fuel generators. We're already planning to carry propane, so if I were to add a generator, I'd either do a propane retrofit or a dual fuel like this one.

[Rawlings]

Originally Posted by weboughtabus

I've been keeping an eye on these Champion Inverter Dual Fuel generators. We're already planning to carry propane, so if I were to add a generator, I'd either do a propane retrofit or a dual fuel like this one.

Any idea how loud they are we have a generator already but its loud I turned it on at one of the campground and people looked at us weird the whole time :/

[Drew Bru]

Originally Posted by Rawlings

So I can get something like 3 pairs of 6v batteries and a few panels. Then keep a generator that isn't loud like a 2000 watt? Would that be sufficient to power the mini split and fridge? Any generator under $1,000 that isn't loud?

We've got 3 pairs of 6v golf cart batteries and they do a bang up job of keeping our 7.5cu ft. fridge running, even when I shut off the solar panels for a day. I can't speak to the mini split AC, but for a fridge it shouldn't be a problem if you've got some solar capacity and, especially, a generator on hand. If you're budget conscious, you might be able to get away with 4 batteries instead of 6, then add a couple more later on if you feel it necessary.

[john61ct]

No, fridge should run 24x7, just make it an efficient one.

2 pairs GCs at 12V 400+Ah should be fine, see how you go with say 600-800W of panels.

There are cheap inverter gennies, but long as they won't get stolen, IMO better to go Honda or Yamaha.

The aircon will need to be small, 8000btu? as efficient as possible not a cheapie, need a soft-start, and careful sizing, best to test before buying. Or go to two gennies.

[Rawlings]

Originally Posted by john61ct

No, fridge should run 24x7, just make it an efficient one.

2 pairs GCs at 12V 400+Ah should be fine, see how you go with say 600-800W of panels.

There are cheap inverter gennies, but long as they won't get stolen, IMO better to go Honda or Yamaha.

The aircon will need to be small, 8000btu? as efficient as possible not a cheapie, need a soft-start, and careful sizing, best to test before buying. Or go to two gennies.

Do you guys have any 7cu fridge you would recommend? Is the 160watt fridge I posted above too much?

[Rawlings]

Originally Posted by Drew Bru

We've got 3 pairs of 6v golf cart batteries and they do a bang up job of keeping our 7.5cu ft. fridge running, even when I shut off the solar panels for a day. I can't speak to the mini split AC, but for a fridge it shouldn't be a problem if you've got some solar capacity and, especially, a generator on hand. If you're budget conscious, you might be able to get away with 4 batteries instead of 6, then add a couple more later on if you feel it necessary.

Is your 7.5Cu ft fridge 12volt or 120volt? For simplification purposes I would rather run everything AC 120. I know I can make things a bit more efficient running 12v like lights etc but I don't want to be running too many different DC and AC circuits.

[Drew Bru]

Originally Posted by Rawlings

Do you guys have any 7cu fridge you would recommend? Is the 160watt fridge I posted above too much?

This is the one we got. Criterion brand....basically a no-name cheapy fridge. It was the right size for our bus though. I suspect the one you posted would be just as good, ours claims 250kWh a year and the one you posted claims 297.

[o1marc]

I bought this Magic Chef 10.1 in Black when it went on sale a month or so back. Think I gave $289 for mine. It uses .014kwh.





https://www.homedepot.com/p/Magic-Ch...00WE/302245066