Inverter size

[4x4FF]

Hi all,

I just got my new residential fridge installed in my 5er. It is a whirlpool WRT111 and it is 10.7 cu ft. I love it so far. With the unit being at ambient temperature (and never having been ran I might add) I plugged it into a kill a watt meter for start up. After watching it for some time the absolute highest wattage I observed was 120 and that was briefly. Normally it ran between 80 and 90 watts while running. I know that the kill a watt isn't sensitive enough to show the peak wattage at compressor startup so that number may be a bit higher.

My question is what size inverter would you guys recommend?

Before we begin, I just want to say I would love to get a 5000 watt inverter and run with 8 6v batteries....but.....That can't happen right now. I have NO intention of boondocking. I only want the inverter to power the fridge while traveling and maybe during campground power outages. I will be running off of 2 6v interstate batteries. What size inverter can I get by with? I am looking at a Xantrex ProWatt in either the 600 or 1000 watt output. Money matters so if I can save $100 by going with the 600 that is fine with me. If you guys can recommend a good inverter other than the Xantrex in the $100 to $250 price range I am all ears. I just want a PSW inverter. I just want to make sure I have enough to power the fridge while I am on the road. I also purchased the Xantrex Transfer relay. What do you think or what other information can I provide?

Thanks,

Steve

[Racine96]

Mine came with 1,000 and works well.

[JTrac]

Check out www.donrowe.com. They have a 1000w KISAE pure sine wave for $189 this week. I bought one from them a couple of years ago to replace the factory installed msw. It runs our Samsung 19cf French door. It has worked flawlessly with our 2 6 volt batteries. Be sure to keep the run from the batteries to the inverter as short as possible and use the recommended wire size, which will be big stuff. Also, I got an automatic transfer switch as part of the package that automatically changes to the inverter when I unhook from shore power and vice versa. Mighty handy. I found them to be very helpful and knowledgeable when I called them. I think I saw the Xantrex 600 on sale also.

[Padlin]

Wet Coast wrote:
Hi all, something to consider is charging those suckers back up once they are drained. Drawing down 440 ah to 1/2 way is roughly 200 amps of charge to have to gain back.

Unless you were talking about your setup, the OP has 2 6v batteries at 220Ah, not 440.

[pianotuna]

Hi,

I would go with a 2k inverter as it allows more flexibility to run other items. It is awfully nice to be able to nuke a cup of coffee.

[Wet_Coast]

Hi all, something to consider is charging those suckers back up once they are drained. Drawing down 440 ah to 1/2 way is roughly 200 amps of charge to have to gain back.

I am experiencing this now as we run 2 CPAP machines among other small loads while boondocking. I have 4 6v 240 ah batteries. I figured a 20 amp Xantrex charger would suffice. Well 200 amps equates to 10 hours to recharge the batts to full on the gennie. That is unacceptable. I am now looking at at least a 40 amp charger. Unless my napkin math is off.

my .035

[hugemoth]

If this is a "frost free" refrigerator it will also have a heater that can draw quite a bit of current when the timer turns it on about once a day. Could be over 600 watts.

[Me_Again]

Installing an AMP Hour meter is a good helper to manage your battery bank.

http://www.solar-catalog.com/sys_mon.html

http://www.xantrex.com/power-products/power-accessories/linklite-battery-monitor.aspx

Chris

[Padlin]

Steve, using Fred's numbers, you'd get 1 day out of your batteries. It is recommended you not drop below roughly 50% of the rated battery capacity to prolong their life. So you have roughly 110 amps of usable power, subtract Fred's 115 amp daily draw and you are just under the 50% mark. You need a decent size generator, or solar and more batteries, or stick to CG's with hookups.

I have about the same batteries, solar, and a 3 way fridge that draws 14 amps. Best I can do is use the fridge on 12 volts while I travel where the TV provides 10 of the 14 amps the fridge needs. 2 batteries are just not enough to run a fridge for long.

[12thgenusa]

Golden_HVAC wrote:
No matter how much you conserve, you can not drop below about 35 AH on a typical RV battery draw.

I know you have quoted that 35 AH daily parasitic draw quite frequently, but I suspect that is somewhat higher than most folks. Most rigs now have 9 volt battery powered CO and smoke detectors. Each person should measure for themselves what their draw is. Mine is only 300mA or about 7 to 8 AH per 24 hour period.

The idle draw from my ProWatt 2000 if I let it run night and day would only be about 14 AH for a 24 hour period. I believe the ProWatt 600 would be slightly more than half that.

[4x4FF]

Golden_HVAC wrote:
Hi,

The 600 watt probably will handle the job just fine. The 1000 watt will consume more power to run the same load that running a smaller inverter near it's full rated load.

I found that out running my TV and satellite dish. When using my built in 1500 watt inverter, my total draw might be 8 amps, but changing to the 300 watt inverter will use a total of about 5.8 - 6 amps. It has much smaller transformer, and smaller capacitors, ect, so not nearly as much parasitic draw.

A pair of 6 volt batteries are the minimum with that load. Anything smaller, and the voltage will 'dip' to far when starting the compressor, and you might never recover, unless the engine is on, or you have a huge solar system that is putting out more than say 20 amps!

80 watt load - figure about 8 amps from the battery into the inverter into the load.

Your propane CO leak detectors team up to use about 1 amp per hour, or about 20 AH daily. No matter how much you conserve, you can not drop below about 35 AH on a typical RV battery draw. With your electric refrigerator, add about 80 amp hours daily, and you will be good. So yes you 'could' go boondocking, with about 3 solar panels - this place has 140 watt on sale for $229 recently.

SunElec.comp

Have fun camping!

Fred.

Thanks for the input. The info you provided is where I get a little fuzzy. The batteries I have are rated at about 220 AH. If I follow correctly I should be in the neighborhood of 2 full days just running the fridge and counting parasitic load. Is that correct??
I do eventually want to explore the solar route. I just have too many other projects in the works right now.

Steve

[Golden_HVAC]

Hi,

The 600 watt probably will handle the job just fine. The 1000 watt will consume more power to run the same load that running a smaller inverter near it's full rated load.

I found that out running my TV and satellite dish. When using my built in 1500 watt inverter, my total draw might be 8 amps, but changing to the 300 watt inverter will use a total of about 5.8 - 6 amps. It has much smaller transformer, and smaller capacitors, ect, so not nearly as much parasitic draw.

A pair of 6 volt batteries are the minimum with that load. Anything smaller, and the voltage will 'dip' to far when starting the compressor, and you might never recover, unless the engine is on, or you have a huge solar system that is putting out more than say 20 amps!

80 watt load - figure about 8 amps from the battery into the inverter into the load.

Your propane CO leak detectors team up to use about 1 amp per hour, or about 20 AH daily. No matter how much you conserve, you can not drop below about 35 AH on a typical RV battery draw. With your electric refrigerator, add about 80 amp hours daily, and you will be good. So yes you 'could' go boondocking, with about 3 solar panels - this place has 140 watt on sale for $229 recently.

SunElec.comp

Have fun camping!

Fred.