Electrical Questions....Refrigerator swap..burro - Fiberglass RV


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Old 08-23-2006, 02:34 PM   #1
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Name: Jim
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Hey

So I have tried to work with my Ice box......used frozen water bottles...and I dont think this is going to work for me...

I have seen a couple 3 way fridges...but at 500.00 plus installation....I am looking at 1/2 the cost of my Burro...

So I came across a Haier 1.8 fridge 59.00 it uses 115 volts/60hz cfc free and is quiet..

my question....

If i install this unit in place of my ice box...install an invertor...do you know which size would work the best?

can I drive with this unit connected and power the fridge with out compromising my rigs electrical?

How long will this power the fridge after its been disconnected form the rig and its on DC power only....single deep cycle battery

Is there a way to have this wired...run on dc when traveling..and switch to ac when plugged in to a ac equipted site...

looking how to best use my Burro and have a cold refrigerator

My only dc hook up in my burro are the two interior side lights..it looks like it had an electrical water pump that was replaced with a manuel unit...wires still there....

my AC unit is hard wired to the fused outlet

looking for options searching as well

Thanks

Jim
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Old 08-23-2006, 03:35 PM   #2
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Quote:
Hey
So I came across a Haier 1.8 fridge 59.00 it uses 115 volts/60hz cfc free and is quiet..
my question....

If i install this unit in place of my ice box...install an invertor...do you know which size would work the best?
[b]That depends on how much current the fridge draws. If your 110v fridge draws say 150 watts then maybe a 200 watt inverter would be plenty. The trouble with inverters is that they draw power even on standby and the bigger the inverter the more they draw on standby. They're also about 80-85% efficient that means a 15-20% loss of power on the translation. Smaller inverters lose less. Try to get by with the smallest inverter that will still run the fridge.

can I drive with this unit connected and power the fridge with out compromising my rigs electrical?
[b]Should work ok. I'm working on a similar install. My GE Fridge (4.3 cu ft) draws about 140 watts ... I also have a single group 27 deep cycle battery ... I'll let you know if it works. The tow vehicle charging system should give maybe 10 to 15 amps of power ... in theory that's enough. Maybe that's just wishing we'll see. The wiring seems a little light for that load and I don't know if the TV voltage regulator will see that demand and try to supply it.

How long will this power the fridge after its been disconnected form the rig and its on DC power only....single deep cycle battery
[b]Depends on the size of the battery but in keeping things simple ... a 100 amp hour battery should be able to give up 10 amps (120 watts) for about 3.5 to 4 hours (depending on temperatures) before getting to 50% charge which is the most you want to discharge the battery before recharging it. The bigger the battery bank the longer you can run. Two 100 amp hour batteries wired in parallel will more than double that time

Is there a way to have this wired...run on dc when traveling..and switch to ac when plugged in to a ac equipted site...
[b]Yes ... the simple solution is to plug the fridge into the inverter when traveling then unplug it and plug it into the site A/C power when parked ... the really cool solution is to have an inverter/charger with automatic transfer switch that handles that function for you plus recharging the battery and all wired into the house circuits. Mucho expensive though. About $300 bucks plus install.
Here's to keeping the beer cold.
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Old 08-23-2006, 03:57 PM   #3
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What Capt Ron said is quite true. However, my experience with inverters (Namely cheapie 'modified sine wave' type) is less than desirable for some applications including compressor motors. The AC wave produced by these inverters is not really a true sine wave but one that may cause your motor to overheat and activate its internal thermal circuit breaker and shut down till it cools off. This is what happened with mine. I eventually used a true sine wave inverter- more expensive but, at least, solved my problem. I am using a 10 year old dorm type fridge that still draws 1 amp at 120v but 10amps at 12v. This allows me enough time for my 3-4 hour travel to keep the fridge cold and then I will plug into AC at my destination. Your newer fridge may be more forgiving in using a modified inverter- only a test will tell.

Terry
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Old 08-23-2006, 05:33 PM   #4
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what invertor do you guys recommend....Brand?

Vector...monster..Radio shack?

I have some DC lines that are not being used...electric water pump removed...

so I plan on using these lines for a power invertor

I also was thinking about installing an additional ac outlet under the sink tied to the the Burro's only outlet....is this an option? if so, how many can be linked to the same line?

Thanks

Jim
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Old 08-23-2006, 07:09 PM   #5
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Quote:
what invertor do you guys recommend....Brand?

Vector...monster..Radio shack?
[b]
I wired up a 350 watt Vector today but it is modified sine wave ... so we'll see if it'll run the fridge ... testing is going on now ... the inverter seems to surge quite a lot and the battery voltage is all over the place ... I'll let it run for a couple of hours and then see if there's any cooling going on...if not then we'll have to get a true sine wave inverter

I have some DC lines that are not being used...electric water pump removed...
so I plan on using these lines for a power invertor
[b]
They may not be heavy enough. My 350 watt inverter specifies 10 awg up to 10 feet from the battery (that's the DC side wiring) You need to consult the manual for the inverter... input wattage exceeds output wattage by the inefficiency of the inverter. 150 watts out probably means 175 or more in ... at 12 volts that's a sizeable load which means big wires especially over a long run.

I also was thinking about installing an additional ac outlet under the sink tied to the the Burro's only outlet....is this an option? if so, how many can be linked to the same line?

[b]Yes, no limit I can think of ... except that a 15 amp circuit is still a 15 amp circuit... you can easily daisy chain outlets or outlets off of a GFCI outlet. One GFCI can protect all of the downstream outlets. I assume here that you're talking about the external A/C power feed from a campsite? ... also your A/C power feed should enter your RV directly to a circuit breaker. Branch ciruits should run from the breaker panel to the outlets or appliances... Probably 15 amp circuits if you're using the typical size 12 household type wiring. Be sure to keep the black and white wires on the correct terminals (white goes on the silver terminal)

Thanks

Jim
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Old 08-24-2006, 05:56 AM   #6
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OK Guys,

Sorry to report that the experiment failed ... as Terry predicted ... fridge won't run on the cheap inverter that I had left over from a boat project. (Vector 350 watt) The compressor heated up ... same symptom as an electric motor trying to run on too low a voltage ... probably due to the square sine wave thing. The cheap inverters also do not read correct voltage on an ordinary digital meter either ... about 30v too low ... manufacturer says it will read correctly on a better meter ... RMS type such as Fluke... well that's not the point ... if it won't read 110v on the cheap meter, the fridge and similar motors won't run on it either.

Back to the drawing board ... I found a pure sine wave inverter on the internet 300/500 watt for $150 ... if that works it'll still be cheaper than the $500 3 way fridge. Project for next year though.
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Old 08-24-2006, 07:32 AM   #7
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Quote:
OK Guys,

Sorry to report that the experiment failed ... as Terry predicted ... fridge won't run on the cheap inverter that I had left over from a boat project. (Vector 350 watt) The compressor heated up ... same symptom as an electric motor trying to run on too low a voltage ... probably due to the square sine wave thing. The cheap inverters also do not read correct voltage on an ordinary digital meter either ... about 30v too low ... manufacturer says it will read correctly on a better meter ... RMS type such as Fluke... well that's not the point ... if it won't read 110v on the cheap meter, the fridge and similar motors won't run on it either.

Back to the drawing board ... I found a pure sine wave inverter on the internet 300/500 watt for $150 ... if that works it'll still be cheaper than the $500 3 way fridge. Project for next year though.
Thanks for the update and report. Good info.
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Old 08-25-2006, 11:55 PM   #8
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So I contacted this company that sells sine wave inverters..

They informed me that i dont need a pure sine wave but a modified sine wave..

They asked what wattage my fridge put out.....I had to look up the conversion...

120 volt .8 amp 96 watts..... They are going to get back to me with an inverter
for it......

What do you think?
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Old 08-26-2006, 04:47 PM   #9
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Quote:
So I contacted this company that sells sine wave inverters..

They informed me that i dont need a pure sine wave but a modified sine wave..

They asked what wattage my fridge put out.....I had to look up the conversion...

120 volt .8 amp 96 watts..... They are going to get back to me with an inverter
for it......

What do you think?
Based on my experience it won't do.
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Old 08-26-2006, 08:19 PM   #10
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Quote:
So I contacted this company that sells sine wave inverters..

They informed me that i dont need a pure sine wave but a modified sine wave..

They asked what wattage my fridge put out.....I had to look up the conversion...

120 volt .8 amp 96 watts..... They are going to get back to me with an inverter
for it......

What do you think?
Hi Jim,

Capt Ron thoroughly tested his Vector 350 watt modified sine wave inverter. It was concluded that it would not work for his fridge. I tested both a Cobra 450 watt and a Jazz 300 watt modified sine wave inverter with a small fridge, too. Both overheated the compressor motor. Now if the place that you are dealing with would like to give you a written guarantee that it will work, or your money back (and maybe a written clause that they will replace your fridge if it burns up), I'd say go for it. However, never say never. It may work. You never know till you try.

I became quite curious as to why the modified causes the motor to overheat. Now, I'm no electrical engineer (but I play one on TV)!

Here is what I found:

The modified inverter does not output anything resembling a Sine Wave AC waveform(normal household Electricity). The peak voltage is lower than the peak voltage of the sine wave waveform. I captured this on an oscilloscope to illustrate:

Click image for larger version

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A normal Sine Wave looks like this:

Click image for larger version

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A motor likes to have a smoothly increasing and decreasing wave at AC (Alternating Current) 60Hz (cycles per second) in order to match the same increasing and decreasing magnetic field as it turns around. When using this 'modified' voltage, however, it's like switching DC (Direct Current- like directly from a battery) off and on 60 times a second in the motor. No wonder it overheats!

Modified sine wave inverters do have uses. I have used them with my Cell phone charger and to charge my laptop while on the road. A TV would be a good use for one (I have done this twice) and have used it to power a new low wattage box fan (with no overheating) This is why say that it may possibly work with a newer fridge. The compressor possibly may accept a slightly lower and distorted voltage.

Hope this helps,
Terry
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Old 08-27-2006, 01:40 PM   #11
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Name: Jim
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Well

i decided to not move my garage refridgerator into my Burro...I went to Target yesterday and bought a Chefmate Thermo Electric Refridgerator.... its a 1.7 size

I have never seen a unit like this...its not like those little 6 pack coolers....

Its only 70 watt draw at 110 volt/ 60 hz

Target gift card.... Total on sale price 60.00

It has a white led light that comes on when open the door....

After plugging it in I had it cool in about 1.5 hrs.....I then adjusted the thermostat down to 2

This Morning everything was nice and cool it runs almost silent There is no motor to cycle on and off

The unit has a drip tray underneathe that I am going to modify with the old ice box drain tube..so I can still use it as an Ice box in a pinch

I had a bear of a time modifying my fiberglass to place this unit inside.. I have to cut out somemore in a bit....

What are you guys using to cut holes in the fiberglass? I was using and older jig saw with a fiberglass blade... still took awhile to cut through....I made a plastic bubble out of painting tarp to collect all the dust and minimize the spread...

also wanted to know if anybody has any tips on a trim for the fridge... is there any
kits you can buy?

I plan on running a test with this unit with an invertor to see if this motorless unit will work just as well of fail like the rest...

I think I will have better results..I hope..
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Old 08-27-2006, 02:05 PM   #12
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Quote:
Well

i decided to not move my garage refridgerator into my Burro...I went to Target yesterday and bought a Chefmate Thermo Electric Refridgerator.... its a 1.7 size.....
Sounds like a sweet little unit- 1.7 is a good size for a thermo-electric unit! I'll have to check out Target and see it. I like the idea of the white LED for the inside light. Let us know how it works out!


I use a scroll saw (or Jig saw) using the straight (non angled) blade to cut fiberglass (on the inside cabinet). However it dulls the blade really fast and after about 1 foot, had to change it. It does cut without splintering and chipping. On the outside fiberglass, I used a standard 1.5" hole saw cutting from the outside inw ith a cordless drill. Did a pretty good job.

As far as trim goes, I really need to get some new door trim. Now that you have asked about trim, I would bet that it would do great on the fiberglass around the fridge. JC Whitney (www.jcwhitney.com) has a huge variety of trim styles, sizes and thickness in white, black, and even chrome.

Keeps us informed,
Terry
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Old 08-27-2006, 02:40 PM   #13
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Target has them on sale today for 55 just read the paper....
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Old 09-07-2006, 10:32 AM   #14
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More Testing ...

I just did another fridge/inverter test ...with the camper parked in the driveway. I used a Vector 1200 watt inverter wired directly to a group 27 deep cycle battery.

Surprise, surprise...! it seems to power the little fridge just fine despite the fact that it's a modified sine wave type (read cheap type) ... The compressor starts just fine and does heat up but then compressors heat up normally. After an hour or so, the fridge was cooling as it should be and the compressor was cycling on and off as I think it should be also.

I also checked battery voltage and I can't see the voltage dropping in an hour so I need some further testing on the road to prove just whether this work or not or for how long. I was also connecting the fridge to the inverter through a 50ft extension cord which probably doesn't help.

The next step is to wire it into the trailer ... that's a project as the battery cables and breaker need to be upgraded ... then I need to wire a short extension cord from the inverter to the fridge ... maybe 6ft ... behind the shower closet... then test it going down the road with alternator hooked up ...

I think it'll work ... maybe 1200 watts is overkill ... but it's what I had so that's what we'll use.

I now suspect that the label on the fridge is wrong ... it says 1.1 amps at 120v or about 130 watts ... the first experiment was using a 400 watt inverter with supposed surge capability to 550 watts... but that refused to start the fridge.

I'm guessing now that the fridge start up load is more on the order of 600-700 watts but that once it gets going, 130 watts will run it. Of course, everytime the compressor cycles, it needs start up current.

The experiments continue. I'm still considering a small portable genset but more for escaping hurricanes than camping use.
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