Odd inverter question

[GallenH]

Which brings me back to my original and second posts.
1. If an inverter would help alleviate the 12v issue, what size inverter would I need and how does it insert into the typical battery, converter, setup?

2. Is the insulation that I indicated in my second post adequate?

3. My fans are placed in the back at a level of the coils and are angling upward. The PW fridge compartment has a vent at the bottom and one at the top of the compartment. Above the fridge the compartment arcs to the upper vent. Would a better placement be behind the top vent with the area surrounding the fans blocked off so that the fans provide the only top vent/draw?

Thanks!

[booster]

Originally Posted by GallenH

Which brings me back to my original and second posts.
1. If an inverter would help alleviate the 12v issue, what size inverter would I need and how does it insert into the typical battery, converter, setup?

2. Is the insulation that I indicated in my second post adequate?

3. My fans are placed in the back at a level of the coils and are angling upward. The PW fridge compartment has a vent at the bottom and one at the top of the compartment. Above the fridge the compartment arcs to the upper vent. Would a better placement be behind the top vent with the area surrounding the fans blocked off so that the fans provide the only top vent/draw?

Thanks!

Middle fans blowing on the condenser work OK, but you need to seal the top vent from the bottom vent from the outside of the van to right up to the condenser to prevent hot air looping back into the fans. The goal is to have no air go in the bottom that does not go out the top, and goes across things that need to be cooled in the process.

[GallenH]

Booster: I've seen fans that go on the inside of the top vent. Some have the remaining area of the top vent sealed around the fan, I assume giving them the greatest draw power. The idea is that the air is drawn through the bottom vent and pushed out the top. Does this design make sense in avoiding the "looping" that has been mentioned?

[peteco]

Originally Posted by GallenH

Booster: I've seen fans that go on the inside of the top vent. Some have the remaining area of the top vent sealed around the fan, I assume giving them the greatest draw power. The idea is that the air is drawn through the bottom vent and pushed out the top. Does this design make sense in avoiding the "looping" that has been mentioned?

Here is another discussion on mods to improve fridge performance. The fan in the top vent, with the rest of the vent sealed around the fan, made the biggest difference in hot weather performance. It also enabled the 12v mode to hold temp while driving as the vent air can only come out the top vent as the fan pulls air into the bottom vent. I use foam pieces to block the top vents except for where the fan air exhausts. It is not pretty and someday I will come up with something that looks better.

http://www.classbforum.com/forums/f8...ance-8484.html

There are several other things I did, with the cumulative effect being that the fridge works OK now.

As you found, in moderate weather the fridge works fine. Last week we boondocked (no electric hookup) in 60-70-degree weather. I had turned off the fan (to conserve electricity) and removed the foam blockers from the top vent. For some reason the fridge control got stuck with the gas burner on 100% of the time, and the fridge temp dropped to 24-degrees.

[Hatteras Jim]

To help answer your question that you asked twice with no responses yet: In theory - To determine the size of inverter, you need to know how many amps of current that your refrigerator requires for running and start up. Once you know the maximum amperage draw (peak), multiply that by 120 (Power = Voltage x Current). For example, an appliance needing 10 amps would require a minimum 1200 Watt inverter. Now, the harder part comes with the wiring of the inverter to the battery side. A 1200 Watt inverter would require 100 amps of DC current to run it. 1200 Watts = 12 volts (battery now) x 100 amps of current. (The amount of current is a little lower when the vehicle is running since your voltage is now ~14.5 volts.) Your wiring has to be oversized a bit when running along the inside of your van because it loses amperage capacity due to excessive heat (Big wire needed). Along with that, your inverter needs cooled and your alternator needs to be sized to handle the additional load.



As you can see from a theoretical standpoint, 12 volts and an extra bag of ice might be easier. Hopefully, someone who has done this can inform you on the specifics of what they used and how it works.



My guess is that this is why the propane mode is used.


To other readers, If I am wrong, please correct; but, please don't bash me too hard...I'm almost seventy and my electrical knowledge is a little dated. Maybe there are new fangled devices that I am not aware of.

[peteco]

GallenH: as a follow-on to my refrigerator comments, I think the most cost effective approach is to improve the fridge performance. The inverter upgrade might not improve performance if you have ventilation issues while driving the vehicle , which I think all vehicles probably have to some degree.

[peteco]

Originally Posted by Hatteras Jim

As you can see from a theoretical standpoint, 12 volts and an extra bag of ice might be easier. Hopefully, someone who has done this can inform you on the specifics of what they used and how it works.
.

I keep a couple of cold packs in the freezer and sometimes transfer these to the fridge when on an extended drive or if sitting in the hot sun.

[GallenH]

peteco and Hatteras: Thanks for the information. Others have chimed in with the emphasis on ventilation as well. I think that the easiest approach might be:

1. Move my fans to the top vent shooting them outward. I might resize the fans (I was using small computer fans) and attach them directly to the inside of the vent.

2. The extra bag of ice is a good point and worth a try. I remain reluctant to run in propane mode while driving, even though others say it's fine and even though I've done it in the past.

Still one unanswered question. Should I have insulation along the side of the fridge? I mean virtually the entire side. Right now I have c.4" of soft insulation at the very back of the side. Should I seal the side so that no warm air comes in (i.e. via metal duct tape)?

[Bud]

Originally Posted by GallenH

Booster: I've seen fans that go on the inside of the top vent. Some have the remaining area of the top vent sealed around the fan, I assume giving them the greatest draw power. The idea is that the air is drawn through the bottom vent and pushed out the top. Does this design make sense in avoiding the "looping" that has been mentioned?

Galen, I've answered that:

"Fans are interesting and not understood sometimes. A fan will draw air from the path with least resistance which is from the sides! I can't see your fans, but it appears that they may be inside the refer compartment and not forcing air to enter from the outside. If not, there may be 'looping' of air in the compartment."

The idea is that the fan is blowing air ONLY from outside the van, in or out.

I was thinking that some electrical geek would answer your question about inverters which is not me. But since the geeks are missing here, a 300 watt inverter will easily power the refer. They are very inexpensive.

Google how to install an inverter in an rv. Keep in mind that you might want some power for an ac tv or satellite receiver or whatever going forward. Still, after installation, simple enough to change out the inverter and even wiring.

Bud

[Bud]

Originally Posted by Bud

Galen, I've answered that:

"Fans are interesting and not understood sometimes. A fan will draw air from the path with least resistance which is from the sides! I can't see your fans, but it appears that they may be inside the refer compartment and not forcing air to enter from the outside. If not, there may be 'looping' of air in the compartment."

The idea is that the fan is blowing air ONLY from outside the van, in or out.

I was thinking that some electrical geek would answer your question about inverters which is not me. But since the geeks are missing here, a 300 watt inverter will easily power the refer. They are very inexpensive.

Google how to install an inverter in an rv. Keep in mind that you might want some power for an ac tv or satellite receiver or whatever going forward. Still, after installation, simple enough to change out the inverter and even wiring.

Bud

Galen, forgot your refer is larger than mine, better make it a 400 water inverter for the refer.

[GallenH]

Thanks, Bud

[604eholston@charter.net]

Hey, GallenH, you have propane which cools better than battery or AC electricity. Use it to cool your fridge going down the road. I have a tape on the dash, says: "fridge on gas when going down the road". My previous Diesel pusher did it sutomatically.