Powering AC unit built into travel trailer with solar?

[OregonMan]

Hi guys I am looking to get solar set up for my travel trailer. It's a 2018 model and has a fairly efficient air conditioning unit built in to the ceiling/roof. I've watched YouTube videos showing how to use solar panels and a power inverter to power a window air conditioner, but what about when the air conditioner is built into the roof of your trailer? My trailer has a "solar ready" 10amp Furrion plug but I doubt that'll be enough to power the AC unit? Is there an adapter I could use to plug the power inverter directly into the 30amp power port on the outside of the trailer that I use to plugin at campgrounds?

Thanks for any tips on powering this built-in AC unit using solar panels.

[Grit_dog]

pianotuna wrote:
Here is how someone has done this:

"Jim Peterson Don Rose -- Good point -- the "cool room" is an 8'x 10' stand-alone building with an 8' ceiling = 640 cubic feet of interior volume but a significant portion of that volume (?18%?) is taken up by two 250 gallon water tanks. Each tank measures about 3'6" by 4' and I'm guessing the height of the square IBC tanks is about 4'? The original plan was to slope the roof/ceiling down at the 15 degrees needed to maximize "winter" solar power yield *and* minimize interior volume at the same time . . . but that's *not* how it got built. ??

The A/C is a Midea U-shaped mini-split (8,000 BTU) which was powered by a Renogy 1,000 watt pure sine wave inverter. The larger Renogy 2,000 pure sine wave inverter has arrived and might even be installed by now. ?? We're up to 2,000 watts of solar panel and that will increase to 2,250 watts soon enough to offset the 33% loss of power we experienced on the super HOT summer days. This means we'll be massively over-paneled the rest of the year but these used solar panels we're using ($63 for 250 watts) keeps it cheap to over panel. ??

This potential for 188 amps of charge is controlled by three Renogy 100/40 charge controllers plus a 4th charge controller of comparable size (forgot the brand on that one ?? ). The inverter is fed from a bank of eight 6 volt deep cycle golf cart batteries. ?? We figure that any power yield above 160 amps will simply be "clipped" and essentially ignored as 160 amps will be w-a-y more than enough during the rest of the year (Sep thru May) when it's not so blazing hot there. 🙂 '

Good grief….

[Huntindog]

afidel wrote:

valhalla360 wrote:

time2roll wrote:

pianotuna wrote:

Gdetrailer wrote:
No matter what "batteries" you use, they all need to be recharged as soon as possible, Lithiums are not immune to this and are not an exception if you want to get the most life for the money you spend.

I thought this was their main claim to fame???

Don't panic. The statement is not true for any practical use.

Storage at 30% to 70% is less wear than being used. No charge asap is needed.

This is consistent with my understanding.
- Lead Acid (which includes AGM & Gel) are happiest sitting at 100% charge.
- Lithium are happies at a mid level of charge. Taking it to 100% for a short period to get all the capacity is OK but leaving it sitting at 100% for long periods is not ideal.

100% is ok if done slowly. For greater longevity you want to keep them between ~20 and 80% state of charge. If you keep them in this middle 60% range you can get 4-500% of the cycle count out of them.

Battle Born says to store theirs at 100%. Do not float them though. 100% then disconnect them.

[pianotuna]

Here is how someone has done this:

"Jim Peterson Don Rose -- Good point -- the "cool room" is an 8'x 10' stand-alone building with an 8' ceiling = 640 cubic feet of interior volume but a significant portion of that volume (?18%?) is taken up by two 250 gallon water tanks. Each tank measures about 3'6" by 4' and I'm guessing the height of the square IBC tanks is about 4'? The original plan was to slope the roof/ceiling down at the 15 degrees needed to maximize "winter" solar power yield *and* minimize interior volume at the same time . . . but that's *not* how it got built. ??

The A/C is a Midea U-shaped mini-split (8,000 BTU) which was powered by a Renogy 1,000 watt pure sine wave inverter. The larger Renogy 2,000 pure sine wave inverter has arrived and might even be installed by now. ?? We're up to 2,000 watts of solar panel and that will increase to 2,250 watts soon enough to offset the 33% loss of power we experienced on the super HOT summer days. This means we'll be massively over-paneled the rest of the year but these used solar panels we're using ($63 for 250 watts) keeps it cheap to over panel. ??

This potential for 188 amps of charge is controlled by three Renogy 100/40 charge controllers plus a 4th charge controller of comparable size (forgot the brand on that one ?? ). The inverter is fed from a bank of eight 6 volt deep cycle golf cart batteries. ?? We figure that any power yield above 160 amps will simply be "clipped" and essentially ignored as 160 amps will be w-a-y more than enough during the rest of the year (Sep thru May) when it's not so blazing hot there. 🙂 '

[msmith1_wa]

This might shed some light on what is needed.

[afidel]

valhalla360 wrote:

time2roll wrote:

pianotuna wrote:

Gdetrailer wrote:
No matter what "batteries" you use, they all need to be recharged as soon as possible, Lithiums are not immune to this and are not an exception if you want to get the most life for the money you spend.

I thought this was their main claim to fame???

Don't panic. The statement is not true for any practical use.

Storage at 30% to 70% is less wear than being used. No charge asap is needed.

This is consistent with my understanding.
- Lead Acid (which includes AGM & Gel) are happiest sitting at 100% charge.
- Lithium are happies at a mid level of charge. Taking it to 100% for a short period to get all the capacity is OK but leaving it sitting at 100% for long periods is not ideal.

100% is ok if done slowly. For greater longevity you want to keep them between ~20 and 80% state of charge. If you keep them in this middle 60% range you can get 4-500% of the cycle count out of them.

[valhalla360]

time2roll wrote:

pianotuna wrote:

Gdetrailer wrote:
No matter what "batteries" you use, they all need to be recharged as soon as possible, Lithiums are not immune to this and are not an exception if you want to get the most life for the money you spend.

I thought this was their main claim to fame???

Don't panic. The statement is not true for any practical use.

Storage at 30% to 70% is less wear than being used. No charge asap is needed.

This is consistent with my understanding.
- Lead Acid (which includes AGM & Gel) are happiest sitting at 100% charge.
- Lithium are happies at a mid level of charge. Taking it to 100% for a short period to get all the capacity is OK but leaving it sitting at 100% for long periods is not ideal.

[time2roll]

pianotuna wrote:

Gdetrailer wrote:
No matter what "batteries" you use, they all need to be recharged as soon as possible, Lithiums are not immune to this and are not an exception if you want to get the most life for the money you spend.

I thought this was their main claim to fame???

Don't panic. The statement is not true for any practical use.

Storage at 30% to 70% is less wear than being used. No charge asap is needed.

[Itinerant1]

Gdetrailer wrote:

pianotuna wrote:

Gdetrailer wrote:
No matter what "batteries" you use, they all need to be recharged as soon as possible, Lithiums are not immune to this and are not an exception if you want to get the most life for the money you spend.

I thought this was there main claim to fame???

Lithiums do a much better job than FLA, AGM or gel, but they are not 100% immune to some degradation if you continually allow them to sit in a partial discharge.

Some of the claim to fame is the not to charge to 100% in order to store them. Reality is you don't really control the charge, the BMS does that. Allow them to store at too low of a charge and you take a chance the BMS will disconnect (BMS has low voltage disconnect built in and most BMS once that is tripped are not able to be reconnected) and now you have an expensive door stop. The Lithium battery pack will have a bit more capacity built in, often about 10% more capacity, but you typically cannot use that capacity due to BMS. The BMS stops you from charging or discharging more than 90% of the battery, good quality BMS will prevent you from using more that extra capacity. Basically that extra capacity is reserved for the BMS and also not allow battery to fall out of normal and stable state of charge range.

I have had some small Lithium batteries swell after being stored in a partial discharge state (inactive for 6 months or more and were not charged until the BMS stopped charging before storing).

The bms is the safe guard for the battery or more likely the cells within the battery.

A properly setup system has the charging device set to stop charging before the bms needs to interact. That's like saying my emergency brakes stop my truck no need to use the brake pedal while operating the truck.

LVD is also part of the bms which does protect the cells/ battery what quality battery manufacturer doesn't allow charging to wake the bms up when it meets their parameters?

Why buy a lfp battery if you're just going to store it, stay with dead lead and buy another cheap replacement when you kill it.

Small lithium batteries are not large lfp batteries, while your experience in lithium maybe useful my 6.5+ years seems to differ slightly using lfp setup fulltime everyday.

[spoon059]

Huntindog wrote:
I have three 15K ACs. In Phoenix AZ, I would not want any less cooling capacity.

What mini split setup would I need?

Pretty sure you are mocking me ( 😉 ) but I've talked to a couple people that have mini-splits in an RV, my parents have one in a multi-room addition they added to their house and I've read and watched a bunch of videos on them. The mini-splits are vastly more efficient than the roof top AC units in RVs. They aren't trying to blow cold air through inefficient and hot ceiling vent systems, they use a moving fan head to blow air throughout a space.

If your camper is big enough, or if you close doors, you may find that 2 mini-splits would work wonders in your camper. Looking at the cost of adding a second rooftop AC to a trailer (about $1200 MSRP), you can buy a DIY mini-split for about half that price.

From what I've experienced and read, the mini-split cools the space MUCH more efficiently, much more quickly, much more inexpensively and much more quietly.

Or, if you are happy with your 3 rooftop AC units, fantastic for you. Personnally I know that I can cool (and heat... its a heat pump) better, for less money, be more comfortable, hold a steady temperature, get much better dehumidification and do it for less money (initially and in energy used throughout its life time) using a mini-split than using rooftop ACs and propane furnace.

[Huntindog]

I have three 15K ACs. In Phoenix AZ, I would not want any less cooling capacity.

What mini split setup would I need?

[afidel]

All the calculations seem to be expecting to cool the whole RV, my plan is to use an inverter based 48V unit just for the bedroom, if it's above 80 when I'm going to go to bed start the AC 2 hours before and cool down the bedroom. With 2-3kW of solar panels and 10-15kWh of batteries this should be easy. It'll be about $12-15k with solar charge controller, Victron inverter, smart shunt, and misc parts.

[Gdetrailer]

pianotuna wrote:

Gdetrailer wrote:
No matter what "batteries" you use, they all need to be recharged as soon as possible, Lithiums are not immune to this and are not an exception if you want to get the most life for the money you spend.

I thought this was there main claim to fame???

Lithiums do a much better job than FLA, AGM or gel, but they are not 100% immune to some degradation if you continually allow them to sit in a partial discharge.

Some of the claim to fame is the not to charge to 100% in order to store them. Reality is you don't really control the charge, the BMS does that. Allow them to store at too low of a charge and you take a chance the BMS will disconnect (BMS has low voltage disconnect built in and most BMS once that is tripped are not able to be reconnected) and now you have an expensive door stop. The Lithium battery pack will have a bit more capacity built in, often about 10% more capacity, but you typically cannot use that capacity due to BMS. The BMS stops you from charging or discharging more than 90% of the battery, good quality BMS will prevent you from using more that extra capacity. Basically that extra capacity is reserved for the BMS and also not allow battery to fall out of normal and stable state of charge range.

I have had some small Lithium batteries swell after being stored in a partial discharge state (inactive for 6 months or more and were not charged until the BMS stopped charging before storing).

[pianotuna]

Gdetrailer wrote:
No matter what "batteries" you use, they all need to be recharged as soon as possible, Lithiums are not immune to this and are not an exception if you want to get the most life for the money you spend.

I thought this was their main claim to fame???

[valhalla360]

spoon059 wrote:
Couple of thoughts... I suggested a mini-split which would draw significantly less than 21 amps or 1000 watts. From what I am reading a 12K mini-split pulls about 4 amps at maximum draw and throttles down substantially from there. I've seen plenty of Youtube videos of people running mini-splits off 8 panel solar systems with larger battery banks. Its doable, likely for about the cost of a typical onboard generator.

I simply don't want to pay those prices to make it silent, so I'm leaning back towards a $1200 Honda 2200 for the occasional dispersed camping.

But, it is absolutely possible with a reasonable solar array and not nearly as expensive as your model.

The difference with inverter based mini-split units is they can adjust the draw to the output desired.

So if for a given rig at a given temp, it takes an average of 7500btu to achieve the desired temp:
- A 15k btu mini-split will draw power enough to put out 7500btu but run continuously.
- A 15k old style roof mount will draw power enough to put out 15k btu but run around 50% of the time.

Net effect is you need roughly the same amount of stored energy. Mini-split units might be a slightly more efficient but not a chance it's going to put out the same cooling btu at a 1/3 the power consumption.