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06-10-2019, 06:27 PM
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#1
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Member
Join Date: Apr 2018
Location: SnapRV.com
Posts: 37
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Running Tiny fridge off Inverter
Hi. I'm trying to run a tiny residential fridge off an inverter It's 1.3 amps. Wattage is not listed. I have tried a 600 watt and 1000watt pure sine wave inverter. I've got 8 guage supply wire from 4 - 6 volt batteries. About 20 feet in length. The inverters shut off after some time. I've tried running them with a fan running. Didn't help. Do I need a better inverter? What do you recommend? Thanks
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06-10-2019, 08:27 PM
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#2
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Senior Member
Join Date: Aug 2001
Location: North America somewhere
Posts: 30,903
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Ohm's Law-voltage (actual) X Amps= 156 watts. This is running watts, startup watts will be as much as 3x higher.
As to 12V wire size, use this online calculator to your advantage: https://www.engineeringtoolbox.com/a...uge-d_730.html
Now to my opinion, I can't imagine the 1000W inverter being insufficient to run that frig., have you measured actual amp draw of that frig with an amp-meter? If that frig is older, it might be the problem.
__________________
2000 Winnebago Ultimate Freedom USQ40JD , ISC 8.3 Cummins 350, Spartan MM Chassis. USA IN 1SG 11B5MX,Infantry retired;Good Sam Life member,FMCA. " My fellow Americans, ask not what your country can do for you, ask what you can do for your country. John F. Kennedy
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06-10-2019, 11:13 PM
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#3
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Senior Member
Join Date: Jul 2014
Posts: 35,419
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A 1000 watt inverter will run the fridge and a 600 may also, but not with 20 feet of 8 gauge wiring.
Move the inverter close to the batteries, use a minimum of 6 ft of 2 gauge cables, and then use a 120 volt extension cord to the fridge.
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06-11-2019, 04:28 AM
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#4
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Senior Member
Join Date: May 2019
Posts: 2,392
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Ditto what Twinboat said.
The inverter should be as close to the batteries as possible. The DC side of the wiring requires much heavier gauge than the AC side. That 8-ga wiring is likely acting as a throttle on the amount of power the inverter can output.
__________________
Richard
1994 Excella 25-ft (Gertie)
1999 Suburban LS 2500 w/7.4L V8
1974 GMC 4108a - Custom Coach Land Cruiser
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06-11-2019, 04:51 AM
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#5
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Registered User
Ford Super Duty Owner
Join Date: Nov 2014
Location: NW Ohio
Posts: 7,114
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Quote:
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Hi. I'm trying to run a tiny residential fridge off an inverter It's 1.3 amps. Wattage is not listed. I have tried a 600 watt and 1000watt pure sine wave inverter. I've got 8 guage supply wire from 4 - 6 volt batteries. About 20 feet in length. The inverters shut off after some time. I've tried running them with a fan running. Didn't help. Do I need a better inverter? What do you recommend? Thanks
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I have an AIMS 1200 watt inverter, same problem.. The inverter doesn't seem to have enough umph to start the compressor.. I even tried a hard start kit on the compressor, still no good. I'm in the process of upgrading to a 2000 watt inverter.
In my case, the inverter is supplied by 4 ft long #6 cables, more than enough power to the inverter.. The 1200 watt inverter should handle it, but it doesn't...
I've been busy on other projects so will get back on this over the weekend.
Pure Sine Wave inverter install – 1999 Southwind 35S
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06-11-2019, 04:52 AM
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#6
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Senior Member
Thor Owners Club Ford Super Duty Owner
Join Date: Jul 2011
Posts: 3,795
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I agree with twinboat. Excessive length of undersized DC cable. I learned the hard way also. Keep the DC cables short and fat and make up for the distance with the AC side.
I have a 10 cuft residential that sips power at 1.4 amps of 120VAC. Not a problem running it but my 2000 PSW inverter with 10' of four gauge DC wire would fault out on the start surge. I now have four feet of 0 gauge supplying DC wire and 10' of 14 gauge wire for AC power distribution and everything performs as expected.
__________________
2006 Hurricane 31D built on a 2006 Ford F53
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06-11-2019, 04:59 AM
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#7
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Senior Member
Join Date: Jul 2014
Posts: 35,419
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Quote:
Originally Posted by Waiter21
I have an AIMS 1200 watt inverter, same problem.. The inverter doesn't seem to have enough umph to start the compressor.. I even tried a hard start kit on the compressor, still no good. I'm in the process of upgrading to a 2000 watt inverter.
In my case, the inverter is supplied by 4 ft long #6 cables, more than enough power to the inverter.. The 1200 watt inverter should handle it, but it doesn't...
I've been busy on other projects so will get back on this over the weekend.
Pure Sine Wave inverter install – 1999 Southwind 35S
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You are undersized on your 12 volt cables. I'm sure your inverter instructions suggests at least 2 gauge cables.
Here is a screenshot of your Aims manual.
Minimum cables are 4 gauge, suggested 2 gauge. 
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06-11-2019, 05:06 AM
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#8
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Registered User
Ford Super Duty Owner
Join Date: Nov 2014
Location: NW Ohio
Posts: 7,114
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Quote:
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You are undersized on your 12 volt cables. I'm sure your inverter instructions suggests at least 2 gauge cables.
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I have some extra #6, I'll double up and see what happens..
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06-11-2019, 05:18 AM
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#9
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Senior Member
Ford Super Duty Owner
Join Date: Dec 2010
Posts: 1,799
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Yup...agree. You might be drawing 40 amps (3x running current) or more during startup. At 20 feet (40 feet round trip) #8 will drop over a volt, which will probably keep you from starting your compressor. Closer...bigger should do it.
__________________
Scott Brownstein
Palm Island, Florida
2015 Georgetown 335DS
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06-11-2019, 06:15 AM
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#10
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Senior Member
Join Date: Aug 2017
Posts: 2,102
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Quote:
Originally Posted by Waiter21
I have an AIMS 1200 watt inverter, same problem.. The inverter doesn't seem to have enough umph to start the compressor.. I even tried a hard start kit on the compressor, still no good. I'm in the process of upgrading to a 2000 watt inverter.
In my case, the inverter is supplied by 4 ft long #6 cables, more than enough power to the inverter.. The 1200 watt inverter should handle it, but it doesn't...
I've been busy on other projects so will get back on this over the weekend.
Pure Sine Wave inverter install – 1999 Southwind 35S
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The cable is too small. I would use minimum #2 cable. The compressor will require over 100 amps @ 12 volts briefly on start-up . Once running , #6 would easily handle the current.
__________________
1993 Tiffin Allegro Bay 32'
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06-11-2019, 06:26 AM
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#11
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Moderator Emeritus
Newmar Owners Club
Join Date: Apr 2014
Location: Southern Indiana
Posts: 19,417
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On my recent 1000w inverter install I went oversize on cables per the many recommendations on the site. Went with 1/0 cables 6' long and do not expect to have any problems. Along with that I replaced the 3/0 jumper to the main fuse for 2000w MSW Inverter with 4/0 as I was using same point for 2nd fuse on the 1000w PSW Inverter.
So far all has been working as intended.
__________________
Steve
2002 Newmar Mountain Aire 4095
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06-11-2019, 02:05 PM
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#12
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Member
Join Date: Apr 2018
Location: SnapRV.com
Posts: 37
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Ooops
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06-11-2019, 02:15 PM
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#13
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Moderator Emeritus
Newmar Owners Club
Join Date: Apr 2014
Location: Southern Indiana
Posts: 19,417
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40' of #2 still sounds small too me.
I would do as Twinboat suggested and move inverter closer use extension cord and see if you still have a problem.
__________________
Steve
2002 Newmar Mountain Aire 4095
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06-11-2019, 02:35 PM
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#14
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Senior Member
Join Date: Jul 2014
Posts: 35,419
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Quote:
Originally Posted by asgweb
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If your using 2 gauge cable, your still stretching it. I used 4 feet of 2 gauge cable on my 1000 watt inverter and its just marginal drawing 800 watts.
You say it shuts down in 10 minutes.
Monitor the volts at the battery until the inverter shuts down.
THEN monitor the voltage at the inverter until it shuts down. Not after but just before it shuts down.
That will tell you if the batteries are to weak to maintain at least 11.8 volts or the voltage is dropping below the inverter shutdown point due to voltage drop due to the long cable run..
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