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Old 05-15-2018, 03:58 PM   #1
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Isata3 - outlets on inverter

Our Isata3 has a 1000W inverter, 2 coach batteries, and 2 solar panels. It runs the TVs fine w/o shore power and I was told I could run my CPAP machine off the inverter too. But the only outlets that run off the inverter seem to be the ones behind the TVs. Is there a way to connect at least one of the outlets near the bed to the inverter? OK, there's always a way if you have enough money, but is it a realistic thing to attempt?
TIA
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Old 05-15-2018, 04:07 PM   #2
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You could.... I don't know if it would run a CPAP machine though. How many amps does your CPAP draw?

A 1000W inverter will only create 8.3 amps at 120v. You won't be able to run a microwave or a vacuum with that.

Also, if you draw that much power at night, your batteries may not last long.
Assuming you have two 85 amp/hr batteries (I don't know what batteries you have), for a total of 170 amp/hrs, if you were only drawing 600W from your inverter (5 amps at 120), that's 50 amp/hrs at 12v. Your batteries would be dead after 3.4 hours. That's without calculating efficiency losses.

Somebody feel free to check my math please....


EDIT:

So I looked up how much power a CPAP draws. At 10cm of water, a CPAP draws about 2.5 amps from 120v.

That's 300 watts.

300W/12v = 25 amp/hrs

170 amp/hrs / 25 = 6.8 hours.

This means your batteries will be stone cold dead after 6.8 hours, not taking losses into account. AND you're only supposed to drain batteries down to ~50% to avoid damaging them. PLUS you've got to recharge them the next day.
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Old 05-15-2018, 04:37 PM   #3
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Think you have your voltages confused. CPAP power supply plate rating is 90 watts from its 24 volt power supply. The biggest part of that draw is generally the humidifier and I turn mine off most of the time and it probably draws maybe 40 watts, which is a little over 3 amps at 12 volts. 8 hours would be 24 AH. Even a single deep cycle 12 volt battery will have at least 100 AH minimum so the CPAP would take you down to 76% percent SOC, not a terrible situation.

Should be no problem adding a more convenient outlet as long as you can get to the Romex feed and add it to the inverter. You could add an additional transfer switch ($50) and the entire breaker that feeds the more convenient outlet. This won't give you more power but a more convenient location to plug in your supply.
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Old 05-15-2018, 06:57 PM   #4
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Thanks for the replies. My machine has a 80w 12vdc power supply. The pressure varies (autopap) but it sounds like it will be no problem. I just have some work to do. I can use extension cords in the meantime.
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Old 05-16-2018, 12:33 PM   #5
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Quote:
Originally Posted by crick616 View Post
Our Isata3 has a 1000W inverter, 2 coach batteries, and 2 solar panels. It runs the TVs fine w/o shore power and I was told I could run my CPAP machine off the inverter too. But the only outlets that run off the inverter seem to be the ones behind the TVs. Is there a way to connect at least one of the outlets near the bed to the inverter? OK, there's always a way if you have enough money, but is it a realistic thing to attempt?
TIA
Long ago I checked my outlets to see which ones were live under inverter power and put a stick on letter I on them. The ones behind the TV's are live as well as the one over the sink, bathroom and the one outside for the tv. Also the one in the long storage by the outdoor shower. Maybe a short extension cord from the bathroom outlet would work. The stock batteries are 100AH each. You could also do an upgrade to Lithium Batteries that are 100AH and can be drawn down to zero SOC without harming them and that gives you about three times the available power.
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Old 05-16-2018, 07:48 PM   #6
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Well, if it's 12v...

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Originally Posted by crick616 View Post
Thanks for the replies. My machine has a 80w 12vdc power supply. The pressure varies (autopap) but it sounds like it will be no problem. I just have some work to do. I can use extension cords in the meantime.
Well, if it's 12v, why run it off the inverter? Run 12v to it, directly from the battery/converter (with a fuse, of course) and plug directly into the CPAP. Better yet, it would be easy to tap off one of the bedroom lights at the fixture, or at the light switch if both 12v and ground are present.

Larry
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Old 05-16-2018, 11:18 PM   #7
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Well, if it's 12v, why run it off the inverter? Run 12v to it, directly from the battery/converter (with a fuse, of course) and plug directly into the CPAP. Better yet, it would be easy to tap off one of the bedroom lights at the fixture, or at the light switch if both 12v and ground are present.

Larry
X2

My motor home has a USB outlet under the mattress on both sides. I bought a 12 volt power cord for the CPAP and tapped into the USB to power a 12 volt outlet on my side of the bed.

Bob Fraser
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Old 05-17-2018, 09:20 AM   #8
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X2

My motor home has a USB outlet under the mattress on both sides. I bought a 12 volt power cord for the CPAP and tapped into the USB to power a 12 volt outlet on my side of the bed.

Bob Fraser
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USB Outlets are designed to be very low power, just be careful they can handle it.
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Old 05-18-2018, 01:06 PM   #9
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USB Outlets are designed to be very low power, just be careful they can handle it.
I was not suggesting powering from the USB outlet but rather connecting to the 12 Volt wires powering the USB. Every 12 volt circut in my RV is protected by a 15 amp fuse and the wiring appears to be 14 gauge. USB outlets are generally 5 volts DC at 1 to 4.1 amps which could not power a 12 VDC CPAP. Sorry if my wording was confusing.
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Old 05-18-2018, 01:15 PM   #10
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Originally Posted by sailski View Post
I was not suggesting powering from the USB outlet but rather connecting to the 12 Volt wires powering the USB. Every 12 volt circut in my RV is protected by a 15 amp fuse and the wiring appears to be 14 gauge. USB outlets are generally 5 volts DC at 1 to 4.1 amps which could not power a 12 VDC CPAP. Sorry if my wording was confusing.
I figured that was what you meant but wanted to clarify for those Electrically Challenged. 14G is indeed good to 15A for runs up to about 10 feet. That is a very good suggestion as the USB Outlets are probably always hot.
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Old 05-18-2018, 01:43 PM   #11
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Here is just what you need!

Quote:
Originally Posted by sailski View Post
I was not suggesting powering from the USB outlet but rather connecting to the 12 Volt wires powering the USB. Every 12 volt circut in my RV is protected by a 15 amp fuse and the wiring appears to be 14 gauge. USB outlets are generally 5 volts DC at 1 to 4.1 amps which could not power a 12 VDC CPAP. Sorry if my wording was confusing.
Here's a great 12v surface-mount outlet for just $2.00. Just drill a hole in the wall near USB outlet and tap in.

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Old 05-18-2018, 01:47 PM   #12
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I'd defer to Cavie...

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Originally Posted by mlmay12 View Post
I figured that was what you meant but wanted to clarify for those Electrically Challenged. 14G is indeed good to 15A for runs up to about 10 feet. That is a very good suggestion as the USB Outlets are probably always hot.
I'd defer to Cavie on this one, but my understanding is that you can wire all the 15A circuits in a house with AWG 14 wire. I would figure that could be up to 50 feet end-to-end and two stories on top of that.

Where did the "10 feet" figure come from?

Larry
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Old 05-18-2018, 03:59 PM   #13
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I'd defer to Cavie on this one, but my understanding is that you can wire all the 15A circuits in a house with AWG 14 wire. I would figure that could be up to 50 feet end-to-end and two stories on top of that.

Where did the "10 feet" figure come from?

Larry
There's a million Wire Gauge Charts and Calculators out there. You probably would be OK for a longer branch if the wire is not in a bundle but it depends on the application, space, temperature, protections and other details. Here is one chart.

12 Volt Wiring: Wire Gauge to Amps | Offroaders.com
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Old 05-29-2018, 11:28 AM   #14
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Running CPAP on batteries witht inverter

Getting back to the original post, we've been using the camper for a couple of weeks with several boondocking experiences and this is what I've learned so far. There is plenty of battery capacity... while boondocking we watched a movie (DVD) and used normal lighting thru the evening. Then ran CPAP all night with humidifier and still had ~2/3 battery left in the morning. Of course, the sun had been up for an hour or so and the solar panels were already recharging things when I got up so I don't know for sure how much the batteries were drained. But it appears that all is good. Thanks for all the comments.
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Old 06-04-2018, 05:59 AM   #15
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"the sun had been up for an hour or so and the solar panels were already recharging things when I got up so I don't know for sure how much the batteries were drained."

The simple but not cheap solution is to install a SOC meter.

This gives a state of charge reading , like a gas gaufe.

It measures the amps out and back in, and keeps track , and is perhaps 10X as accurate as just looking at voltage..

With solar its easy to be fooled because the voltahe read is the charging voltage , not the battery resting state.

Here is one meter ,

Trimetric TM-2030-RV Battery Monitor System

https://www.solar-electric.com › ... › Meters & Monitoring › Battery Monitoring

Trimetric TM-2030-RV Battery Monitor System. ... Bogart Engineering SC-2030 12/24 Volts Solar Charge Controller. $127.00. Description; Additional Information ...
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