Airstream New E1 Package — Generator-less

[Lt Keefer]

I marvel at how some people in the RV community think certain types of recreational vehicles can be good for the environment.

[Beau388]

Originally Posted by RACarvalho

you can make an AC that consumes only 1wh that doesn't mean it is usable.
228wh is 778 BTUs...
If you ever had a 5000 BTU AC you know what it can do (not much) so 778BTUs maybe good to keep your glove box cool ?

By the way 680 watts (12 volts) gets 6,824 btu on the RTX2000 so its EER is about 10. So not bad for a 3 phase A/C scroll compressor with integral inverter. Of course listing above $2,200 makes it of limited use (sorta like the X-15 Cummins diesel).

[DavidEM]

Originally Posted by RACarvalho

You should ask WHY they are not required (at this moment) to have pollution controls...

I don't think you will ever (well forever is a long time!) see emission controls on small IC engines. But some states are starting to ban outright devices that use small IC engines like California banning lawnmowers, leaf blowers, etc. That is a better way than trying to come up with ridiculous emission standards for small IC engines.

David

[Chance]

Originally Posted by RACarvalho

you can make an AC that consumes only 1wh that doesn't mean it is usable.
228wh is 778 BTUs...
If you ever had a 5000 BTU AC you know what it can do (not much) so 778BTUs maybe good to keep your glove box cool ?

You are converting electrical power to air conditioning cooling rate directly, but air conditioners “pump” much more energy than they consume. That’s where Coefficient Of Performance comes in, or for regular non-technical buyers the US government simplified it for them as Energy Efficiency Ratio, or the EER we see listed for comparison.

A typical 5,000 BTU/hr window unit today can have EER of 12, so pulls +/- 420 Watts of electricity at rated weather conditions. My measurements show that at night when it’s cooler, power requirements are even lower.

And if you are wondering, yes, a 5,000 BTU/hr air conditioner can cool a van at night with ease. With a much larger A/C, it will just cycle on and off more. My average cooling power at night is around 300 Watts, and my A/C is old (inefficient) and van is not insulated very well at all.


For what it’s worth (stating only to educate those who don’t know already), it is common in Europe to rate Air Conditioner cooling capacity in Watts instead of BTU/hr as we do in USA. Hence, a 2,000 Watt A/C has a cooling capacity of +/- 6,800 BTU/hr, which makes it a small A/C. With an EER of 12, it would only pull about 570 Watts of electricity. The difference between 2,000 Watts (cooling) and 570 Watts (electrical power) is due to COP.

I only mention this to show that a small well-insulated van doesn’t actually need a huge roof-top air conditioner running at full capacity 24 hours a day. The daily average is much less, which means large battery will last longer during much of the day. I would estimate that from 10 at night to 10 in morning, average cooling requirement is maybe +/- half of what it is at 3 ~ 4 PM on sunny summer afternoon. The concept of powering A/C from batteries isn’t as bleak as it sounds initially if applied and designed correctly. It will cost a lot though.

[16ACE27]

Originally Posted by Beau388

You might want to look at the Dometic RTX 2000 12 volt roof A/C. In econo mode it draws 228 watts of energy. If you have a 12,000 watt hour battery bank that is a couple days of continuous A/C usage with enough power left over to run the lights and cook top. After that you need to run the engine for a couple hours.

It's a 2000 watt 6800 BTU A/C. At 50% duty cycle you can figure 1000 watts per hour. So that's 12 hours on that 12,000 WH battery bank.

"ECO mode"? No info on what that means on their website, no info on how much cooling you get on "ECO Mode" but if 2000 watts gets you 6800 BTUs then 230 watts gets you 840 BTUs; not a lot of cooling.

[HMCSW]

Originally Posted by RACarvalho

They announce last week that California will have rolling brown and black outs beginning in the summer because of the increased demand on the electrical grid.

[Chateau_Nomad]

Originally Posted by HMCSW

They announce last week that California will have rolling brown and black outs beginning in the summer because of the increased demand on the electrical grid.

Just had damaging storms in Ohio last night. AEP announced today "planned rolling service disruptions" to ease stress on the grid... we're also experiencing the first real heat wave this year. Going to be an interesting summer of "shortages".

P.S. My dad bought two Montgomery Wards 5,000 BTU window units in 1968 for $99 ea. Cooled off the bedrooms at night like gangbusters! We just dealt with the daytime heat, but slept in comfort at night!

[Chance]

Originally Posted by 16ACE27

It's a 2000 watt 6800 BTU A/C. At 50% duty cycle you can figure 1000 watts per hour. So that's 12 hours on that 12,000 WH battery bank.

"ECO mode"? No info on what that means on their website, no info on how much cooling you get on "ECO Mode" but if 2000 watts gets you 6800 BTUs then 230 watts gets you 840 BTUs; not a lot of cooling.

As mentioned in post #24 above, 2,000 Watts is cooling capacity and NOT electrical power.

The Dometic RTX2000 is a truck parking cooler designed to draw very little power from truck batteries or auxiliary batteries, and documents state it can operate with as little as 180 Amp-hours. Of course it doesn’t say for how long at that lower level.

ECO mode limits power to 19 Amps, or 228 Watts, which should keep a truck cab cool at night. That could provide 3,000 BTU/hr or more if EER is above 15 which is very doable using present air conditioning technology.

Specifications list current draw at 12 Volts from 10 Amps to 58 Amps, which is 700 Watts maximum. That “maximum” should represent demand during start-up, and if not, during “BOOST” cooling mode where capacity is increased to a maximum for a short time.

This unit is variable speed and thus variable capacity, and like many residential mini-split air conditioners, it’s very possible “BOOST” cooling exceeds 6,800 BTU/hr cooling rate for the allowed 20 minutes before it reverts back to normal Auto cooling.

[Chance]

Originally Posted by Chateau_Nomad

....cut....

P.S. My dad bought two Montgomery Wards 5,000 BTU window units in 1968 for $99 ea. Cooled off the bedrooms at night like gangbusters! We just dealt with the daytime heat, but slept in comfort at night!

Window air conditioners are now available with dual inverter drive to increase efficiency. The smallest unit I’ve seen is 8,000 BTU/hr cooling capacity and has an EER of just over 15; which is pretty good.

So far manufacturers haven’t expanded dual inverter technology to the smaller 5,000 BTU/hr window units, so best EER is still around 12.2. That’s still not bad in that they would require under 400 Watts of electricity at night. The down size is that inverter technology and higher EER adds cost, size, and weight, so would make A/C harder to install in window. I digress though. Point is that this technology is needed badly as an option for RV air conditioning.

[Beau388]

Originally Posted by Chance

Window air conditioners are now available with dual inverter drive to increase efficiency. The smallest unit I’ve seen is 8,000 BTU/hr cooling capacity and has an EER of just over 15; which is pretty good.

So far manufacturers haven’t expanded dual inverter technology to the smaller 5,000 BTU/hr window units, so best EER is still around 12.2. That’s still not bad in that they would require under 400 Watts of electricity at night. The down size is that inverter technology and higher EER adds cost, size, and weight, so would make A/C harder to install in window. I digress though. Point is that this technology is needed badly as an option for RV air conditioning.

I think that is one of the reasons than Thor Industries bought Airxcel in 2021 (Coleman Mach, Surburban, etc). The lack of innovation in the RV products market is evident.

Most of us know at a 3 phase A/C electric motor is more efficient than a single phase AC or any DC motor. With variable frequency, 3 phase A/C motors become variable speed. Phase converters have been around since I was in college (1957). It is just the initial cost that keeps them from adoption. Same thing was true with scroll compressors. Now scroll compressors are ubiquitous in home A/C units and home refrigerator yet my 4 year Coleman Mach heat pump has a single speed, single phase piston compressor.

[16ACE27]

Originally Posted by Chance

As mentioned in post #24 above, 2,000 Watts is cooling capacity and NOT electrical power.

Who expresses cooling capacity in watts when the universal standard is BTUs?

[Chance]

Originally Posted by 16ACE27

Who expresses cooling capacity in watts when the universal standard is BTUs?

Europeans.


As far as I recall, they have done it that way for a long time, even before RV air conditioners. Kind of funny considering we use “British” thermal units and most of them don’t.

[Chance]

Originally Posted by Beau388

I think that is one of the reasons than Thor Industries bought Airxcel in 2021 (Coleman Mach, Surburban, etc). The lack of innovation in the RV products market is evident.

Most of us know at a 3 phase A/C electric motor is more efficient than a single phase AC or any DC motor. With variable frequency, 3 phase A/C motors become variable speed. Phase converters have been around since I was in college (1957). It is just the initial cost that keeps them from adoption. Same thing was true with scroll compressors. Now scroll compressors are ubiquitous in home A/C units and home refrigerator yet my 4 year Coleman Mach heat pump has a single speed, single phase piston compressor.

Agree 100%. As I mentioned before, improving energy efficiency of air conditioning for motorhomes like these Airstream E1 is as important or more so than just throwing more money at buying larger battery banks.

Since air conditioning essentially is what drives the required battery capacity (for given performance goal), it then follows that more money spent on insulation, dual pane windows, higher-efficiency DC air conditioners, etc. may save more in lithium battery cost and also in higher cost to charge battery in same time.

I know motorhomes the size of Axis can get by with a single 15,000 BTU/hr A/C, so a much smaller van may be able to cut that in half with better insulation, windows, etc. If a van can cool adequately with 7,500 BTU/hr or less, then it would only need 50% of battery and 50% of alternator capacity to charge in same amount of time.

I know you already know this, just trying to paint a picture for those who don’t have a good understanding of what an entire system involves. It’s not just larger batteries.


P.S. — Coleman has a 48 VDC air conditioner now. I wonder if they use it on these Airstream motorhomes so inverter wouldn’t be required for air conditioning.

[Bill Johnson]

Are you sure of the battery power 12.1 kWh?

[Bob Denman]

If they're using diesel o power so much stuff: have they increased the fuel tank capacity?
At about 25 gallons or so: it's a bit on the small side...

[Chance]

Originally Posted by Bill Johnson

Are you sure of the battery power 12.1 kWh?

Neither of those is a unit of “”power”. Problem starts there.

Specs for E1 package list useable energy storage as 12.1 KWh. That is energy, not power.

Amp-hours does not correctly define energy or power.

If we know the voltage, then Amp-hours can be converted to energy. In this case it would take about 950 Amp-hours at 12.8 VDC to get 12.1 kWh, which is what Volta specifications list for 4 battery modules. 3 is standard, but these motorhomes apparently have 4.

HOWEVER, Volta system works closer to 52 Volts, so 12.1 kWh is actually +/- 230 Amp-hours. That should confuse everyone.

[16ACE27]

Originally Posted by Chance

Neither of those is a unit of “”power”. Problem starts there.

Specs for E1 package list useable energy storage as 12.1 KWh. That is energy, not power.

Amp-hours does not correctly define energy or power.

If we know the voltage, then Amp-hours can be converted to energy. In this case it would take about 950 Amp-hours at 12.8 VDC to get 12.1 kWh, which is what Volta specifications list for 4 battery modules. 3 is standard, but these motorhomes apparently have 4.

HOWEVER, Volta system works closer to 52 Volts, so 12.1 kWh is actually +/- 230 Amp-hours. That should confuse everyone.

As you said, Amp-Hr by itself is a useless number. Amp-Hrs has to be expressed at a voltage: 100 Amp-Hrs at 12 VDC is not the same as 100 Amp-Hrs at 48 VDC.

[Chance]

Originally Posted by Bob Denman

If they're using diesel o power so much stuff: have they increased the fuel tank capacity?
At about 25 gallons or so: it's a bit on the small side...

Great question. The amount of energy in a gallon of diesel is very high, and can heat water or the inside of motorhome for a long time. Propane tanks store a lot less energy than what the Sprinter fuel tank does, so I wouldn’t worry too much about that in a “Touring” coach which isn’t meant to camp in winter for weeks at a time.

After a comment made by others, I did a quick estimate and determined that charging batteries using alternator in order to power air conditioner should be as efficient overall than using a typical 3.2 kW Onan diesel generator much of the time. If battery was charged while driving, I expect it would use less diesel overall. Either way, fuel shouldn’t be a problem if boondocking just a few days at a time.


P.S. — Sprinters need larger fuel tank, but for added driving range.

[Bill Johnson]

I didn't see the voltage I figured in the 12 volt range. why 52 volts it must cost a fortune. my 48 volt lithium for my golf cart costs enough. I did find it funny on the Airstream trailers it didn't show the battery pack. but it did say that a lead acid battery can only be discharged 50 percent but their lithium can be run down 100% with no ill effect, not from what I've been reading

[Chance]

Originally Posted by Bill Johnson

I didn't see the voltage I figured in the 12 volt range. why 52 volts it must cost a fortune. my 48 volt lithium for my golf cart costs enough. I did find it funny on the Airstream trailers it didn't show the battery pack. but it did say that a lead acid battery can only be discharged 50 percent but their lithium can be run down 100% with no ill effect, not from what I've been reading

Bill, Volta specs show “nominal voltage” at 51.5 Volts.

The useable capacity at 90% Depth of Discharge is 12,132 Wh.

Note Volta uses a different battery chemistry than typical RV batteries.

The higher voltage (51.5 versus 12.8) is strictly a way to reduce maximum required current so electrical cables don’t end up too large. As the system is designed and built more powerful, current could easily exceed 500 Amps if at ~ 12 Volts.

The higher Volta battery and inverter voltage should reduce current to about a quarter of what it would be otherwise.

Battery specs below:

https://1rm4pw3qup7umqlqkbggk81c-wpe...et_11-1-19.pdf