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Old 09-20-2019, 02:50 PM   #1
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2017 Interstate Grand Tour Ext
Marco Island , Florida
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Watt and amp draw of a dometic fridge and freezer in 2017 AI?

We are boondocking with a 400 watt solar system and a 400 amp hour lithium ion battery. We are getting between 200 and 300 watts off the solar during the day but it doesn’t seem to be keeping up with the only power draw in the van.

This is our first time using the system and had the impression we would be able to power the fridge and a few other items for several days.

Any thoughts or direction to resources?

Thanks in advance.
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Old 09-20-2019, 04:35 PM   #2
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Power Measurements From an Airstream Safari 25

Using a Clamp on ammeter and measuring the AC amps and voltage I determined the following power consumption for each of my appliances running on AC. I started with nothing on then computed the increase in power consumption as I turned on each appliance one by one. You are consuming a little power even with nothing on because of LP gas detectors, control panels and whatever else you have in your unit that cannot be turned off.

When you are boondocking, you will not have the power converter on. We always run our fridge on propane when we have no AC.

The lamps in this unit were incandescent. LED lamps will draw much less.


Appliance Status Incremental Wattage
Power converter ON 428
DC Fridge (Dometic) On (gas) 32
AC Fridge On (AC) 294
BR fan On 97
Fantastic Fan Fan Low 78
Fantastic Fan Fan Medium 101
Fantastic Fan Fan High 125
Fantastic Fan Fan Off 0
Lamp One Lamp 94
Lamp Two Lamps 158
Air con (Dometic Penguin) Fan 282
Air Con Fan & Compressor 1350
Furnace Fan On 334
FUrnace Standby 3
Monitor Panel On 7
Pump On 150
Gas H20 Heater On 20
Radio ON 49
Radio Standby 24
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Old 09-23-2019, 09:01 AM   #3
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Incredibly helpful

Thanks so much for the information.
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Old 09-23-2019, 09:12 AM   #4
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Quote:
Originally Posted by wildwilly. View Post
We are boondocking with a 400 watt solar system and a 400 amp hour lithium ion battery. We are getting between 200 and 300 watts off the solar during the day but it doesn’t seem to be keeping up with the only power draw in the van.

This is our first time using the system and had the impression we would be able to power the fridge and a few other items for several days.

Any thoughts or direction to resources?

Thanks in advance.

Wow, I'm impressed with your solar set up and lithium battery capacities. Even if your solar cannot keep up with drains, you should not be significantly depleting your battery. Your impression is correct. You should have several days (or more) of battery capacity assuming your solar is making the contribution you stated. You should have at least 5000 watt hours in your fully charged lithium batteries, of which you can use 80-90%.

My guess is something else is interfering with your solar charging process or you have an unknown energy hog lurking some where. Do you have an accurate SOC (state of charge) meter wired to your system so you can track input & output? Did you upgrade your inverter charger to one that has a lithium compatible setting and is it configured correctly? Same for your solar controller.
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Old 09-23-2019, 09:22 AM   #5
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Originally Posted by Jim J View Post
Using a Clamp on ammeter and measuring the AC amps and voltage I determined the following power consumption for each of my appliances running on AC. I started with nothing on then computed the increase in power consumption as I turned on each appliance one by one. You are consuming a little power even with nothing on because of LP gas detectors, control panels and whatever else you have in your unit that cannot be turned off.

When you are boondocking, you will not have the power converter on. We always run our fridge on propane when we have no AC.

The lamps in this unit were incandescent. LED lamps will draw much less.


Appliance Status Incremental Wattage
Power converter ON 428
DC Fridge (Dometic) On (gas) 32
AC Fridge On (AC) 294
BR fan On 97
Fantastic Fan Fan Low 78
Fantastic Fan Fan Medium 101
Fantastic Fan Fan High 125
Fantastic Fan Fan Off 0
Lamp One Lamp 94
Lamp Two Lamps 158
Air con (Dometic Penguin) Fan 282
Air Con Fan & Compressor 1350
Furnace Fan On 334
FUrnace Standby 3
Monitor Panel On 7
Pump On 150
Gas H20 Heater On 20
Radio ON 49
Radio Standby 24

Jim J. Good info. He has a newer Interstate GT which has a compressor fridge/freezer. But it is a large one and reportedly consumes much more that my little 3.1cf compressor Novacool. Still, his robust battery/solar set up should be doing better for him.

Hopefully, his inverter/charger is more efficient that the figures you show. My concern is whether he upgraded his charging components (battery and solar) to lithium-compatible ones.
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Old 09-23-2019, 11:02 AM   #6
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Hi

There are a number of different fridges out there.

The old style 120V / Propane gizmo will pull about 1A off of 12V when running either on propane or on 120V. It will pull around 3A off of 120V when on shore power while it's trying to cool.

There is a "three way" version of the same ammonia based fridge. It will try to run off 12V as it's heat source. Most reports put the drain around 15 to 20A off of the 12V line. Needless to say, that will nuke a typical battery pretty quickly.

In addition to all that ammonia based stuff, there are indeed compressor based fridges out there. Best guess is that they will pull in the 3 to 4 A range off of 12V. A lot depends on their size so it's only a guess. Even a 4A load is pretty significant in terms of what it does to your batteries.

=====

200 or so watts out of a 400W setup is not all that uncommon. A lot depends on how much overcast there is and how much shade you are in. What is more significant is how many watt hours or amp hours you get in a day. Something in the 500WH range is ok for a shaded site. You can get up around 2,000 WH under ideal conditions. Something like a BMV-712 is very useful for keeping track of this data.

If you are peaking at about 200W and getting 4 "equivalent peak hours" during the day, that comes out to about 800 WH. Converted back to amp hours that is 60AH. A 1A fridge drain will take out 24 AH of that. If you have a control system on the vehicle (Firefly ....) it also will pull about 1A. Between the two, they will use up what the solar is putting in.

Bob
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Old 09-23-2019, 11:26 AM   #7
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Op has a 2017 Interstate class b with large compressor fridge with separate freezer. Plus, if he has not updated to lithium compatible solar controller and inverter/charger, they may not be topping out his 400ah lithium batteries.
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Old 09-23-2019, 07:50 PM   #8
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Take a look at the Files Section on the FB Group. https://www.facebook.com/groups/Airs...erstate/files/

Look at the Boondocking file and you can get all the power draws for a 2016. Something is odd with the OPs consumption. With reasonable sunlight, I have no issues running for a couple days on 320 AH AGM and 300 watt solar.
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Old 09-23-2019, 08:28 PM   #9
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In my experience, solar will typically produce between one times panel wattage and four times panel wattage in watt hours each day when not under tree canopy. For 400W, that would be between 400Wh and 1.6kWh of production per day. 400Wh when under overcast skies, 1.6kWh with clear skies and a depleted battery bank or large load. That means you should typically get between 30AH and 120AH of battery charging each day without significant tree canopy. I don't know how many Amp Hours your refrigerator uses per day or what your other battery usage is per day. Therefore, I can't tell you how long your battery will last.

I had 400W of solar on my last Airstream. I ran my refrigerator on propane and rarely ever needed to charge my batteries with anything but solar. I could run two fantastic fans all day, and all other lights and water pump as needed. I could run my furnace on propane all night, fantastic fans all day, pumps and lights, and even watch several hours of TV with the inverter and still replace the power used each day with my 400W of solar. So I believe the refrigerator is the source of your problems. How many Amps does the refrigerator use each day? Is it possible to run the refrigerator on propane?

I have a DC refrigerator on my new Airstream Globetrotter 27'. I have 600W of solar on the roof. I haven't figured out if I can run that DC refrigerator over 24 hours and produce enough solar to recharge the batteries, but initial tests do not look promising. DC refrigerators consume many Amps while running. Mine is rated to use 14A, but seems to only use 10A after it is cold. It does cycle on-and-off once its cold which then takes less battery. I've learned I can run it all day with minimal solar input on my 230AH battery. I haven't used it enough to really know if I can use it on DC overnight after a sunny day. I know I can't run it on DC for more than 10 hours on a cloudy day.

I wish I could help you more. I thought I'd share what I know from 250 days of using 400W of solar with my previous Airstream (no DC refrigerator) and ten days of experience with my new Airstream with 600W of solar and a DC refrigerator.
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Old 09-23-2019, 10:27 PM   #10
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I have a 2017 AI with 300 watts flat mounted solar and 240 AH of AGM batteries and a good solar charger (not the AI SunExplorer junk). I use only the large 12 Volt fridge in fridge mode. After a typical California sunny day I can run the fridge all day and night and still have 12.5 Volts in the morning. The fridge takes 5 amps.

The panels produce up to 15 amps in total.
~15A x ~14V = ~210 watts so about 70% efficient.

I have the propane switch in the off position (it uses 0.7amps) and use just 1 or 2 LED lights in the evening. In the morning I can use the propane heater (electric fan) and bathroom fan as needed. The voltage will drop to ~12.4 but recover once I turn off the heater and fan. This is all before the sun comes up.

An AGM battery will be 50% depleted at something like 12.2volts or maybe less. (It is hard to get a good definition of what the voltage is for 50% depletion.)

With your lithium setup you should have capability far in excess of what I described above.
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Old 09-24-2019, 05:52 AM   #11
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Quote:
Originally Posted by CorkWins View Post
I have a 2017 AI with 300 watts flat mounted solar and 240 AH of AGM batteries and a good solar charger (not the AI SunExplorer junk). I use only the large 12 Volt fridge in fridge mode. After a typical California sunny day I can run the fridge all day and night and still have 12.5 Volts in the morning. The fridge takes 5 amps.

The panels produce up to 15 amps in total.
~15A x ~14V = ~210 watts so about 70% efficient.

I have the propane switch in the off position (it uses 0.7amps) and use just 1 or 2 LED lights in the evening. In the morning I can use the propane heater (electric fan) and bathroom fan as needed. The voltage will drop to ~12.4 but recover once I turn off the heater and fan. This is all before the sun comes up.

An AGM battery will be 50% depleted at something like 12.2volts or maybe less. (It is hard to get a good definition of what the voltage is for 50% depletion.)

With your lithium setup you should have capability far in excess of what I described above.
With this information, I believe you can run your refrigerator on DC 24/7 with your 400W of solar under average solar conditions. Given the refrigerator uses 5A while running, and assuming it runs 50% of the time; that's 60AH per day. Then adjust your other usage based on solar conditions, being frugal on overcast days and with significant tree canopy, the solar should be able to catch up on sunny days with insignificant tree canopy. Then its up to you to park in campsites that get ample sunshine on the panels.

An Iphone App that I use to choose campsites and orient my Airstream is called "Lumos". It overlays the sun's path each day over a camera picture on your phone. Here is an example of how I use Lumos. In this example, I was in an extremely tree-filled location, a very full campground, and had little choice for getting a good solar location. The campsite had electric hookup so I wasn't too concerned if I could not maintain the batteries with only solar. But this site did provide 500WH to 700WH of solar production from my 600W array - the low side of my above estimates and just enough to maintain the batteries without using the refrigerator on DC. http://www.airforums.com/forums/f448...ml#post2291314
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Old 09-24-2019, 07:08 AM   #12
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Originally Posted by wildwilly. View Post
We are boondocking with a 400 watt solar system and a 400 amp hour lithium ion battery. We are getting between 200 and 300 watts off the solar during the day but it doesn’t seem to be keeping up with the only power draw in the van.

This is our first time using the system and had the impression we would be able to power the fridge and a few other items for several days.

Any thoughts or direction to resources?

Thanks in advance.
Have you looked in the AS owners manual etc. briefcase which came with your unit? There should be a section in the owner's manual with the fridge specs at the back IMO. Or a separate pamphlet etc. from the mfg. which gives detailed specs.

Standard "phantom loads" which may also apply? Propane detector, sub-woofer, stereo, fridge warming strip around door, etc..

https://www.google.com/search?q=batt...com&gws_rd=ssl

Also check for hidden lights in storage areas which may have been left on.

Good luck,

Peter
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Old 09-24-2019, 08:00 AM   #13
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Mystery Amp Draw

Great input from all. I plan on taking the coach to a specialist to help me track the issue down. I suspect it may have something to do with an incident earlier in the trip. The propane system was inoperative and we took it to a repair facility in Marble Falls, Texas. They spent all day trouble shooting the issue which they claimed was not a simple solenoid issue but a wiring issue to the solenoid. The propane system now works but the main disconnect switch does not shut down the coach and the inverter is constantly on which I believe is a significant draw.

Very frustrating on the road with trusting repair issues to an unknown shop! We have had numerous other issues on this trip which I will chronicle on a separate thread.
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Old 09-24-2019, 10:46 AM   #14
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Originally Posted by wildwilly. View Post
Great input from all. I plan on taking the coach to a specialist to help me track the issue down. I suspect it may have something to do with an incident earlier in the trip. The propane system was inoperative and we took it to a repair facility in Marble Falls, Texas. They spent all day trouble shooting the issue which they claimed was not a simple solenoid issue but a wiring issue to the solenoid. The propane system now works but the main disconnect switch does not shut down the coach and the inverter is constantly on which I believe is a significant draw.

Very frustrating on the road with trusting repair issues to an unknown shop! We have had numerous other issues on this trip which I will chronicle on a separate thread.
WILDWILLY - yes, the inverter is a significant load if it is ON. It is even a significant parasitic drain of about 0.4A (400mA) when just in standby. Managing parasitic loads is important to enable running refrigerator with your setup.

You said you have 400AH of lithium batteries. This is not a stock Airstream system so many of us may not be able to help you with your custom electrical system. Who did your battery upgrade?

I have 400W solar system with BlueSky MPPT controller feeding 440AH AGM battery system. I can run the refrigerator and other items without problems as long as I get reasonable sunshine. I'm very careful to keep inverter OFF when not needed.

Good luck,
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Old 09-25-2019, 09:22 AM   #15
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Originally Posted by wildwilly. View Post
Great input from all. I plan on taking the coach to a specialist to help me track the issue down. I suspect it may have something to do with an incident earlier in the trip. The propane system was inoperative and we took it to a repair facility in Marble Falls, Texas. They spent all day trouble shooting the issue which they claimed was not a simple solenoid issue but a wiring issue to the solenoid. The propane system now works but the main disconnect switch does not shut down the coach and the inverter is constantly on which I believe is a significant draw.

Very frustrating on the road with trusting repair issues to an unknown shop! We have had numerous other issues on this trip which I will chronicle on a separate thread.
Hi

If you had the 400AH of lithium installed by somebody, I would get them involved with any strange electrical issues .....

Bob
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