Temporary Inverter power for a short trip

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Warboar

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Mar 26, 2019
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Folks I have a bit of a dilemma.  I am heading out next month on an Elk hunt in Colorado.  I had intended to get an inverter system set up this summer prior to the trip however my son had to have surgery and the bills pretty much sucked up a good deal of the money I had set aside for that. 

What I need to do is be able to have power to the outlets in the trailer so I can charge small electronic devices such as cell phone and handheld GPS units as well as run a CPAP machine.  I have two generators but would prefer not to run them since there will be others in our group who are tent camping and I really don't want to disturb them.  During the day I can throw the small generator on and charge the batteries or fire up the main generator if I need to run appliances. 

I have a 1500 Watt inverter that I would like to wire into the batteries and then run an extension cord with adapter to the shore power slot.  I would wire in an isolation switch to isolate the converter so it doesn't try and charge the batteries if there isn't a breaker already. 

Would this system work for the week I would be needing to use it?  I know it's not an ideal situation but it's what I can realistically work with in the short time I have.  Once I get back from the trip I would go ahead and wire in a permanent system when funds became available. 
 
How many batteries do you have. Does your rv have 12 volt outlets that you could plug in small inverters for charging the gps and phones etc. The cpap im not familiar with, but there are lots of threads concerning running them off inverters. The forum wont seem to let us add links tonight. Take a long extension cord for your generator so you can put it far away from the tenters. Lend them a radio for the night.
 
Sorry I forgot to add info on my system.  I have two Interstate 6V Golf Cart batteries. 

I honestly don't know about the CPAP machine as it belongs to my uncle.  I'll find out the information on how many amps it draws when he calls me back.  He has to have the machine since his sleep apnea is very bad.  I do have two small Goal Zero solar panels that can charge a cell phone fairly quickly and i'm sure it would charge the other gadgets just as quick but we will be hunting during the daylight hours and like I said I would prefer not to run the generators at night since the others will be in tents.  I know my little yamaha generator at idle is very quiet but even at idle out in the middle of nowhere you can hear it and it sounds louder than it would in town. 
 
Your system should work, but I wonder why you don't just plug CPAP and chargers directly into an extension cord from the inverter?  There seems to be no real need to tie it into the trailer outlets for those few items.

Those two 6v batteries should get you through a day & night ok, but what about Day #2? You are going to need quite a bit of generator time bring the batteries back near full charge each day.  I'm talking hours. Once the batteries come up to 70% or so, the rate at which they charge really slows down.

Remember that the CPAP is probably rated at 120v rather than 12v, so the amps have to be multiplied by 10x to get battery amps. Plus another 10% for inverter power loss.
 
Gary,
Thanks for the reply. I was thinking about the extension cord but my 5th wheel is 34? and my uncle will be on the back bunk bed. So I was thinking I would either have to bring the cord through an open window or some other means while the extension cord to the shore power plug would not require that. Also I could run my small generator during the daytime. With one gallon of gas it will run for almost 10 hours at 40% load and 7 at 3/4 load. That should work for recharging everything I think.
I will just keep the fridge on gas power so I don?t put anymore load on the inverter than needed.
My plan once the funds are available is to install a 300-400watt solar system with a better inverter and add a couple more batteries.
 
Gary RV_Wizard said:
Remember that the CPAP is probably rated at 120v rather than 12v, so the amps have to be multiplied by 10x to get battery amps. Plus another 10% for inverter power loss.
Click to expand...

Some are that way and some are 12 volt DC. Mine is 12 Volt DC and has one of those so called pucks in the cord. I purchased this particular brand/model so that I could just plug it into a 12 volt cigarette lighter outlet which is about 6' away from my machine.
 
Also what type of inverter do you have, is it a pure sine wave model, or a modified sine wave, if modified sine wave, I would suggest testing it with the CPAP to make sure the CPAP is happy about the modified sine wave output.
 
If all you need is a CPAP I would use a smaller inverter (say 300 watt or 2x the CPAP's need  but you can use the 1500.. I'd sneak an extension cord into the bedroom and that's all folks.  perhaps a fan if you need it and the CPAP.

Way easier than trying to feed the whole rig  and less load on the battery. With a pair of GC-2 you have about 1KWH of usable power So do not be wasting it.
 
Well now i'm back to square one.  Wish I could catch a break.  Just tried testing the inverter and it's not working.  So now I have to go and buy a new one. 

Any recommendations on an inexpensive  Inverter?
 
Odds are very high the CPAP uses a power supply to convert 120V to some lower DC voltage, maybe even 12V.  Find out what the details are and maybe you'll discover you don't need an inverter at all.  This website implies that 12V CPAP machines are not that uncommon.

https://www.cpap.com/cpap-faq/Power

Phones readily charge from 12V sources as well, no inverter needed.

Mark B.
Albuquerque, NM
 
Thanks Gary for the link.  I noticed several others on Amazon that were in my price range as well.  One of my friends suggested that I just use my small Yamaha generator as it shouldn't be at more than an idle if I leave the Fridge on Gas and keep the furnace down to a minimum temp.  He said his wall tent is pretty heavy fabric and he has run his Honda EU2000 which is similar to my Yamaha with no issues.  I do have a 90' 10ga extension cord that I could take along just incase it does get noisy. 
After the trip I will go ahead and spend the money needed to do it right the first time rather than buy twice. 

I appreciate everyone's advice and insight.
 
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