Setting up 12 Volt System for Best Dry Camping and CPAP Use

[ttondro]

We are brand new owners of a great Sundance 3000 MK. 4 nights so far! We have some specific questions related to batteries and dry camping and using my CPAP. I'll try to be specific!

1. We have one flooded 12 volt battery.
2. I was told to have a dedicated 12 volt line put into the bedroom so that I can plug in my CPAP "car charger".
3. We want to dry camp without a generator for as many as 5-6 nights. We can live without the microwave etc.and just use our LED lights and furnace occasionally to take off the chill.
4. We cannot charge our batteries when the rig is stowed and think that perhaps we should get AGM batteries. It was suggested that if we get a par of 12 volt and one fades, we can take it to a gas station to charge overnight. We would bring the batteries home to trickle charge between trips.

Are we on the right track? Which brand/seller of AGM batteries is recommended for price and quality? Any recommendations on chargers?

Thanks!
Tracy and Barbara, newbies.

 

[pegmikef]

A lot of folks use solar panels. I would use four Trojan 6 volt batteries because of the greater amperage. If you search this forum for solar panels you should find several threads discussing them and some installation examples and tips.

 

[porthole]

AGM batteries are pricey, so you do not want to start with improper charging. They require a different charge rate then standard flooded batteries.
You certainly don't want to take them out and run them down to any gas station for a charge.

Something to consider:
2 quality deep cycle batteries, 12 volt in parallel
2 quality golf cart 6 volt batteries in series
4 quality golf cart 6 volt batteries in a series - parallel setup
A sufficient solar panel array and controller to keep the batteries up.

Taking the batteries in an out and bringing home to charge will get old real fast.

A "trickle charger" is designed to maintain a charged battery at full charge, not charge a low battery.

You might want to reconsider a small inverter type generator like the Honda 1000 or 2000 "suitcase" generators.

 

[campcrew]

Our quick solution for our first dry camp was a jump starter that has a battery and a 12 volt outlet. Fully charged it ran a cpap all night. We used a Honda 2000 during the day when needed and recharged the jump starter at the same time. Very portable, and nice to have jump starter just in case.


Sent from my iPad using Tapatalk

 

[mbopp]

I don't have a CPAP machine, but I've heard there's a heater on them that draws a lot of power and you should turn it off when running on a battery.
Even if you switch to 2-six volt batteries I doubt you'll be able to go the 5-6 days you want. You MIGHT get 2 days out if your single 12V now, but 1 day may be more realistic.
Consider a generator or adding solar panels. I'm running 2-12V batteries and a Honda 2000i generator. We camp in some shaded areas so solar wouldn't work unless I had 100' of cable.
Add a master cutoff switch to your batter(ies) and disconnect them when in storage. Parasitic draws like the propane detector and radio will deplete a battery in a week or 2. I put a master on-off switch in the radio / DVD player to disconnect it totally when we dry camp. No need to go to AGM's.

 

[evolvingpowercat]

Suggest you put a battery voltage monitor into your TT. You will want to make sure you don't let your battery voltage drop below about 12 volts or you risk not being able to put in your slide out when its time to leave if you use too much of your stored battery energy. See below - if you want to make your batteries last you won't even let them get down that far voltage wise.

I have 200 Amp-hours (A-H) of 12 volts stored energy in my 2011 Heartland Edge. If the North Trail is like the Edge you can fit 2 group 24 100 A batteries side by side on the battery shelf and wire them in parallel (80 amp protective fuse suggested in the +12 volt connecting wire). Given you have a North Trail which is simliar to the Edge I don't think you are going to want to burn your pass-thru storage compartment with the 6 volt batteries, I suggest you just double up on 12 volt batteries.

1. For maximum battery life you want to drain batteries from 100% to 50% so you normally will not want to use more than 100 Amp-hours without replenishment. Worst case you can go from 100% to 20% which gives you 160 A-H. Going below 20% really shortens the battery life. Under light 12 volt load aproximately 12.6 is near 100% left, aproximately 12.3 volts is 50% left, and aproximately 12.0 is 20% left.

2. At a minimum you will use 20-A-H per day just running the 12 volt control boards for the Jensen stereo, refrigerator, water heater, and the propane detector. Other loads to factor in or lighting and 12 volt chargers for cell phones, etc. That is your base storage loss when dry camping.

--- loads you can control ---

3. Possible big load is the furnace, on a cold night the 12 volt powered furnace blower can use 40 A-H. Blower uses almost 10 amps when running.

4. Lighting with the OEM 10 watt bubs each bulb uses 1.2 A-H per hour it is on. You can cut this by a factor of 8X by changing the bulbs you use a lot to LED ones. Personally I left the bulbs I don't leave on more than a few minutes a day alone to save cost.

Bottom line: If you get a 80 watt solar panel and a solar charge controller you can replenish up to 40 A-H per day on a sunny day, less if cloudy. More solar panels = more replenishment eacy day. As mbopp suggested, having a small gasoline generator is the safe thing to do in case of camping without sun for a while.

----- If you need 120 volts AC when dry camping -----

If you add a 120 volt AC from 12 volt DC inverter to the setup then you can use a lot of battery storage in a big hurry. For example making a single pot of coffee with a 8 cup coffee maker will use 20 A-H of battery storage. Microwave would use 2 A-H per minute of cooking.

 

[Bohemian]

This is a medical concern. Get a generator, either built in or a small portable of sufficient size. Be safe. Be healthy.

 

[Jim.Allison]

Look at my list of solar below, youtube search learn a little about solar, you might be surprised at how inexpensively you can install a system that supports things like CPAP, TV, and general AC appliances. With a properly sized solar system and a properly sized inverter and if you put DC devices such as the CPAP on a DC line, rather than inverter power. My system looks good but is really not all that good, it was my first project. My inverter is too big my batts are just right and my panels and charger is just right. My system will run EVERYTHING in my rig EXCEPT air conditioning. If you want to run everything except microwave and air conditioning you can get away with half of what I have. Heck, I can get away with 1/3 less than what I have. Do a little research, its all at your fingertips and its not all that hard. I had a blast doing mine.

I personally do not believe the 6v in series is the best way to go, I believe that Trojan Renewable energy 12v batts are better, T1275s to be exact. Two T1275 would provide 300 amp hours of service at the 20 hour rate. Its more efficient to run the CPAP on DC than to invert it then transform it back to DC. With a 1500 watt system you can do most anything you want, all you need is capacity and the ability to recharge. message me If I can help. BTW most of my sourcing was through Amazon and Ebay, I bought nothing used, it was all new, I usually went straight to the sellers website once I found what I wanted on Amazon or Ebay. I rarely paid freight and I did not pay sales tax. Good luck

 

[recumbent615]

Not going to disagree with any of the suggestions above. A small Generator is a good thing to have and Solar if you are camping long term dry is also good. I do have a CPAP Machine and it does have a heater but it is as you know optional, especially in the summer when it is already humid. I would also look at the CPAP machine you have and see if you can run it directly off of 12 volts, Mine is a 12V system ( and I believe many are ) so when I plug it in at home it is converting 120V AC to 12V DC. Converting 12DV to 120V AC to 12V DC is not efficient no matter how you do the math. If your CPAP machine is 12V DC get an adapter and skip the Inverter...

Good Luck with what every you decide for a setup - but as others have said, if it needed for health and safety then get the generator.

(EDIT: I see that I was beaten to the direct 12V recommendation - just means I type slow, and great minds think alike )

Kevin

 

[recumbent615]

I found this on Cpap.com YouTube it may help some

 

[Jim.Allison]

I have been keeping up with this subject as you guys have been writing, I have the phillips remstar. I ordered the cigarette lighter adaptor for the machine yesterday, less than $20. I found it online at a CPAP mask and parts supplier. I'm going to install a DC line straight off the batteries into a permanent powerport installed in a wall near my bed. What this will do for me is allow me to turn off my inverter which uses a couple of amps to make the AC electricity that gets turned back into DC for the CPAP. The CPAP is the only reason that I use the inverter at night during the Spring summer or fall.

 

[Jim.Allison]

A good setup includes a generator, a solar system with batt and inverter as well. My batts can support the inverter and the CPAP overnight no problem, the inverter uses more power than the CPAP. A generator will use a significant amount of fuel but is a viable option, but introduces the dangerous condition of carbon monoxide poisoning which all RV generator manufacturers warn against, plus the associated noise that your camping neighbors do not appreciate and you have quiet time that you will have to contend with as well. So solar emerges at the most efficient way to power CPAP. BUT like you, I agree that converting batt to ac then back to dc is a waste.

A couple of days ago, i ordered the cigarette adaptor that will run my CPAP, I intend to install a port connecting it directly to the batt, increasing efficiency significantly. And eliminating any danger of carbon monoxide poisoning. I received it today and it appears to be a quality product and I think it will be a plus to my clean quiet solar power system. And I guarantee that my solar batts can run that CPAP with heater for 3 days non stop without bothering my neighbors.

Not going to disagree with any of the suggestions above. A small Generator is a good thing to have and Solar if you are camping long term dry is also good. I do have a CPAP Machine and it does have a heater but it is as you know optional, especially in the summer when it is already humid. I would also look at the CPAP machine you have and see if you can run it directly off of 12 volts, Mine is a 12V system ( and I believe many are ) so when I plug it in at home it is converting 120V AC to 12V DC. Converting 12DV to 120V AC to 12V DC is not efficient no matter how you do the math. If your CPAP machine is 12V DC get an adapter and skip the Inverter...

Good Luck with what every you decide for a setup - but as others have said, if it needed for health and safety then get the generator.

(EDIT: I see that I was beaten to the direct 12V recommendation - just means I type slow, and great minds think alike )

Kevin

 

[ICamel]

It sounds like the best option for the OP is solar. With that said, here is how I dealt with powering my CPAP and humidifier. I must use the humidifier as we don't get that much humidity here in Oregon. I have a Resmed CPAP and you must use 110V when using the humidifier. My solution was to install a dedicated Deep Cycle 12V battery underneath the bed and attach an inverter to the battery. I found that I could run the CPAP/Humidifier for 3 nights using this setup. Since I usually camp for up to 5 nights, I added a second Deep Cycle battery in parallel with the first. I can sleep for 5 nights without having to recharge these dedicated batteries. I park the 5r next to our house when not camping and have electric hookup, so I attached a 1.5v battery Charger/maintainer to these dedicated batteries. They are fully charged in less than a week. I know that the inverter is not the most efficient method, but it works best for me. I also have an 8A battery charger that I can power from a 2000W generator to recharge the batteries when needed. You just have to prop the bed up during the charging period to allow adequate ventilation. I have been doing this for over 7 years, and it works for me.

 

[Jim.Allison]

Yes you have a good set up even though you have to use the inverter. Well cared for batteries and a properly sized inverter will pull the load on that CPAP power hog. Problem is that each battery has a published 100% charged voltage. Many 12v batteries are 50% discharged at 12.4 volts. People cannot do what you are doing because their batts are empty before they even start. There is where the difference is. You are defeating it by having good batts and enough capacity as well.

It sounds like the best option for the OP is solar. With that said, here is how I dealt with powering my CPAP and humidifier. I must use the humidifier as we don't get that much humidity here in Oregon. I have a Resmed CPAP and you must use 110V when using the humidifier. My solution was to install a dedicated Deep Cycle 12V battery underneath the bed and attach an inverter to the battery. I found that I could run the CPAP/Humidifier for 3 nights using this setup. Since I usually camp for up to 5 nights, I added a second Deep Cycle battery in parallel with the first. I can sleep for 5 nights without having to recharge these dedicated batteries. I park the 5r next to our house when not camping and have electric hookup, so I attached a 1.5v battery Charger/maintainer to these dedicated batteries. They are fully charged in less than a week. I know that the inverter is not the most efficient method, but it works best for me. I also have an 8A battery charger that I can power from a 2000W generator to recharge the batteries when needed. You just have to prop the bed up during the charging period to allow adequate ventilation. I have been doing this for over 7 years, and it works for me.

 

[porthole]

Just how much power does a CPAP draw?
I'm guessing at least 5 watts. Many inverters will not switch on with a less then 5 watt draw.

I don't use one, but from the sound of it, they all operate on 12 volts DC and come with what is needed to to use household AC. Do they manufacturers offer direct 12 volt DC hook ups?

 

[recumbent615]

Just how much power does a CPAP draw?
I'm guessing at least 5 watts. Many inverters will not switch on with a less then 5 watt draw.

I don't use one, but from the sound of it, they all operate on 12 volts DC and come with what is needed to to use household AC. Do they manufacturers offer direct 12 volt DC hook ups?

Duane,

Not all CPAP machines will Run on 12VDC some run on 24 VDC ( but there are 12 to 24V converters) Still there are some units that have integrated power supplies and only take 120V AC... But I believe that all of the current units on the market use external supplies and run on one or the other DC power level. But as was stated earlier in this thread - the humidifier draws a lot of current where as the standard draw fro a CPAP machine without is very little. . For instance my Unit is rated at 120VA (Watts) @ 24 VDC resulting in a MAX draw with humidifier of 5A @ 24VDC or 10A at 12VDC assuming MAX draw as a constant that would result in my 125AH Batteries providing only 12.5 hours of power.

without the Humidifier that equation is much different, Max Draw is only 75VA providing for a 6.3 Amp Draw @ 12 VDC ( MAX ) or Nearly 20hours ( again at MAX usage )

Typical values are better for my unit:

80VA or ~7A @ 12VDC with the Humidifier 17 hours @ 125AH
20VA or 1.7A @ 12VDC Without.. nearly 74 hours @ 125AH..


Ofcourse all of these numbers are based on my paticular unit and are only used to show that usage with a humidifier requires supplemental power to keep the batteries charged even when running directly off DC power for more than a few days...

Kevin -

 

[ICamel]

To expand on what Kevin has indicated, the electrical draw also depends on the output air pressure setting of the CPAP machine. The higher the output pressure, the more electrical current draw.
Without a humidifier my CPAP draws 1.13A at 6cmH2O while the draw is 2.12A at 20cmH2O
With the humidifier the amperage use is 3.86A at 6cmH2O and 4.85A at 20cmH2O
Most durable equipment manufacturers have this information published.

 

[Jim.Allison]

This weekend I had several projects, among the projects was to install a DC power port in the bedroom so I can run my CPAP with heater directly off my battery, rather than invert for a transformer that subsequently converted back to 12v DC.

Last month I sent off for a DC cord for the CPAP, Its a quality item and comes with several glass fuses that fit inside the plug. The fuse recommended for my Philips respironics CPAP with heater was 5 DC amps.

I have been putting off this project because I could not figure out how I was going to fish the wire down to the batts. I decided to look beneath the bed to see if there was a hole that I could use to fish a wire to the basement. It was there I discovered that there was a bundle of wires for the lights above the bed. I tested the voltage and pulled the proper fuse from the DC panel, once I identified it I check to see what all was on that DC circuit. There was nothing except the two lights. So I tied in to the positive and negative of the bundles and marked "DC outlet" on the fuse label in the box. I plugged it in and it works fine along with all the light on the circuit as well. The inverter internal power demand is almost as much as what I can run the CPAP on all night.

So check under your bed and see if you have some DC under there and wire a DC power port, do away with the transformer if you can. Just eliminating this one thing, will have me charged up early in the day.