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    1. · Registered
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      1,128 Posts
      For all of the people promoting that:
      • They have a small AGM battery pack
      • Example single 100 amp-hr, 12 volt AGM house battery or even double this
      • Have it hooked up to an inverter and can run 1000 watt + loads without any problems
      • Please do a simple test where you actually run it at 1000 watts for 5 minutes
      • Not 500 watts - really 1000 watts of load
      • Please record the battery voltage every 15 seconds and see how long it stays above 12 volts

      If it goes below 12 volts, then in my mind it has failed to meet the needs of a van that also has a refrigerator or fuel heater because the majority of them will shut off.

      My guess is that a lot of people promoting this concept will come back and say "oh - you can only do that with the engine running".

      Now take it somewhere where it is actually cold outside and let it cold soak overnight and see what happens.

      Yeah...... My wife is from Missouri. Show me.
      So I did run this test and learned a few things:
      -my 1000w microwave is only running at about 800 watts. I am guessing this is due to the fact that Im using an $80 1200 watt max MSW inverter to run it. It still heats and runs fine and I boiled the cup of water in a few minutes. I didnt realize that it was running at reduced power until I did this test. This is the inverter: https://www.amazon.com/gp/product/B075ZPMJZH/ref=ppx_od_dt_b_asin_title_s00?ie=UTF8&psc=1

      -My voltage dropped to about 11.2 v after running the MWO (Microwave Oven) for a few minutes. At first glance and from @HarryN s posts this sounds like a major issue but while MWO was running I turned on my compressor fridge which draws 5 amps and my propex furnace which draws 2 amps and they all ran happily at the same time. So I looked up what the cutoff voltages actually are for these devices. I checked the manual for the isotherm fridge I have and it does not cut out until it gets down to 10.9 volts. I also have a webasto chest freezer, it doesnt shutoff until voltage drops to 11.1 volts and that is on the highest setting. The propex manual says it does not shut off until voltage drops below 10v. Manuals for reference below:

      Test was performed on a cold morning with overnite temps in the 20s and interior temp of the van in the mid 30s at the time of the test. Battery is a 100ah interstate AGM mounted under drivers seat on its side. Battery purchased and installed in 2017, it is 4 years old and has been used and abused in extreme temperatures during that time, primarily I use the van for skiing in Colorado, many, many camping trips with overnite temps below 0f.

      After 5 min of testing, battery SOC was about 92%, I turned on engine and got about 50 amps from alternator which quickly dropped to 40-30 amps. Screenshots from victron battery monitor below.

      My conclusions from the test:
      • @HarryN is right that voltage does drop below 12v with high amp draw from a smaller capacity system like mine (single 100ah AGM).
      • @HarryN is mistaken that a majority of fuel heaters or compressor fridges will turn off when voltage falls below 12v. Maybe there are 12v appliances that dont operate below 12v, curious to know what these are if they do not include compressor fridges/furnaces?
      • real world experience running fridge/furnace/MWO and other loads simultaneously is that the voltage drop is a non-issue for MY real world use. After 4 years of use I did not even notice voltage drop while simultaneously use MWO/Fridge/Furnace because I have never experienced a low voltage shutoff.

      Running all 3 devices (MWO, furnace, fridge):
      73615


      Charging immediately after test:
      73616
       
    2. · Registered
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      1,952 Posts
      So I did run this test and learned a few things:
      -my 1000w microwave is only running at about 800 watts. I am guessing this is due to the fact that Im using an $80 1200 watt max MSW inverter to run it. It still heats and runs fine and I boiled the cup of water in a few minutes. I didnt realize that it was running at reduced power until I did this test. This is the inverter: https://www.amazon.com/gp/product/B075ZPMJZH/ref=ppx_od_dt_b_asin_title_s00?ie=UTF8&psc=1

      -My voltage dropped to about 11.2 v after running the MWO (Microwave Oven) for a few minutes. At first glance and from @HarryN s posts this sounds like a major issue but while MWO was running I turned on my compressor fridge which draws 5 amps and my propex furnace which draws 2 amps and they all ran happily at the same time. So I looked up what the cutoff voltages actually are for these devices. I checked the manual for the isotherm fridge I have and it does not cut out until it gets down to 10.9 volts. I also have a webasto chest freezer, it doesnt shutoff until voltage drops to 11.1 volts and that is on the highest setting. The propex manual says it does not shut off until voltage drops below 10v. Manuals for reference below:

      Test was performed on a cold morning with overnite temps in the 20s and interior temp of the van in the mid 30s at the time of the test. Battery is a 100ah interstate AGM mounted under drivers seat on its side. Battery purchased and installed in 2017, it is 4 years old and has been used and abused in extreme temperatures during that time, primarily I use the van for skiing in Colorado, many, many camping trips with overnite temps below 0f.

      After 5 min of testing, battery SOC was about 92%, I turned on engine and got about 50 amps from alternator which quickly dropped to 40-30 amps. Screenshots from victron battery monitor below.

      My conclusions from the test:
      • @HarryN is right that voltage does drop below 12v with high amp draw from a smaller capacity system like mine (single 100ah AGM).
      • @HarryN is mistaken that a majority of fuel heaters or compressor fridges will turn off when voltage falls below 12v. Maybe there are 12v appliances that dont operate below 12v, curious to know what these are if they do not include compressor fridges/furnaces?
      • real world experience running fridge/furnace/MWO and other loads simultaneously is that the voltage drop is a non-issue for MY real world use. After 4 years of use I did not even notice voltage drop while simultaneously use MWO/Fridge/Furnace because I have never experienced a low voltage shutoff.

      Running all 3 devices (MWO, furnace, fridge):
      View attachment 73615

      Charging immediately after test:
      View attachment 73616
      Thanks for running the test.

      The espar heaters and a number of 12 volt refrigerators do in fact cut off at 12 volts.

      I don't have a list of which ones do / don't, but it is interesting that your propane heater is more resistant to this effect.

      Some simply will not re-start until the voltage has risen again above 13 (as in going into a re-charge cycle).

      It is a big issue when the battery voltage has gone low and the heaters will not start when it is cold.

      I have also had customer come in who had 12 volt refrigerators that will trip off and the van owners food has spoiled as a result.

      Your test is an interesting single data point though and I will keep it in mind. I still would not go down that path as a general rule for customer projects as I cannot predict exactly what appliances they will use.
       
    3. · Registered
      Van #2 2021 EXT
      Joined
      ·
      6,172 Posts
      So I did run this test and learned a few things:
      -my 1000w microwave is only running at about 800 watts. I am guessing this is due to the fact that Im using an $80 1200 watt max MSW inverter to run it. It still heats and runs fine and I boiled the cup of water in a few minutes. I didnt realize that it was running at reduced power until I did this test. This is the inverter: https://www.amazon.com/gp/product/B075ZPMJZH/ref=ppx_od_dt_b_asin_title_s00?ie=UTF8&psc=1

      -My voltage dropped to about 11.2 v after running the MWO (Microwave Oven) for a few minutes. At first glance and from @HarryN s posts this sounds like a major issue but while MWO was running I turned on my compressor fridge which draws 5 amps and my propex furnace which draws 2 amps and they all ran happily at the same time. So I looked up what the cutoff voltages actually are for these devices. I checked the manual for the isotherm fridge I have and it does not cut out until it gets down to 10.9 volts. I also have a webasto chest freezer, it doesnt shutoff until voltage drops to 11.1 volts and that is on the highest setting. The propex manual says it does not shut off until voltage drops below 10v. Manuals for reference below:

      Test was performed on a cold morning with overnite temps in the 20s and interior temp of the van in the mid 30s at the time of the test. Battery is a 100ah interstate AGM mounted under drivers seat on its side. Battery purchased and installed in 2017, it is 4 years old and has been used and abused in extreme temperatures during that time, primarily I use the van for skiing in Colorado, many, many camping trips with overnite temps below 0f.

      After 5 min of testing, battery SOC was about 92%, I turned on engine and got about 50 amps from alternator which quickly dropped to 40-30 amps. Screenshots from victron battery monitor below.

      My conclusions from the test:
      • @HarryN is right that voltage does drop below 12v with high amp draw from a smaller capacity system like mine (single 100ah AGM).
      • @HarryN is mistaken that a majority of fuel heaters or compressor fridges will turn off when voltage falls below 12v. Maybe there are 12v appliances that dont operate below 12v, curious to know what these are if they do not include compressor fridges/furnaces?
      • real world experience running fridge/furnace/MWO and other loads simultaneously is that the voltage drop is a non-issue for MY real world use. After 4 years of use I did not even notice voltage drop while simultaneously use MWO/Fridge/Furnace because I have never experienced a low voltage shutoff.

      Running all 3 devices (MWO, furnace, fridge):
      View attachment 73615

      Charging immediately after test:
      View attachment 73616
      Thank You @afox for performing this & posting the results/conclusions.

      We just go home from about a week in our van & I gotta say I really appreciate the Propex for the low electrical consumption it seems to use. We rarely use 120vac & have pretty efficient 12vdc appliances / led lights.

      I have a Chinese Diesel heater in my cabin (but not my BM 712 installed yet), but from using this diesel heater, it seems to be a heavier user of 12vdc then the Propex.

      I have already purchased a Propex HS2800 for my 2021 build - you know why !!
       
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