How to increase power for my cpap use.

Kristi33

I have a 2018 320 S Boondock Lite.  I generally do dry camping with SOFT. I have a 100 w solar panel on top that trickles power to the wet battery. I have a power adapter to plug in my cpap.  It works well for 1 1/2 nights and then the battery is dead. I am frugal with the power,  don't use the tv, usually lanterns, just the fridge.

I need advise as what to do? ie increase the power via another battery (I don't know where it would fit in the box), add a similar type and size with my battery, 6a Lithium battery, solar power, generator, suitcase?  I'd appreciate any ideas My head is spinning. 

VictoriaP

Is your CPAP adapter 110v or 12v?
Do you absolutely have to use the humidifier on it, or can you go without for a few nights?
Current 12v battery group size and available amp hours (both should be on the battery label)?
Running the fridge on battery or propane?

I researched this one for my late husband some time back. Most CPAPs do have a 12v cable available and use far less power that way. The humidifier portion usually increases the power draw, so 12v and no humidifier is the most efficient. So that’s the first thing to address.

The group 24 lead acid deep cycle battery that most dealers provide has at most 70 amp hours, only half of which is actually available. The fridge is NOT efficient at all on battery, so that definitely should be run on propane. Even then, your capacity is pretty low in terms of available power. Simplest battery upgrade on a Boondock is to move to a 100ah or greater group 27 or 31 battery, possibly an AGM type as they are theoretically more tolerant of deep cycling than a traditional lead acid. It will fit in the tub, and buy you a bit more time without recharging.

Next would be how best to recharge. Solar is great IF you are able to get the panels into full sun. That’s extremely dependent on where you are camping, though. Anything but full sun and you may not be getting much from them. A suitcase setup with decent length cables would allow you to park in the shade while potentially putting the panels in a sunnier spot. Or you may want a gas or propane generator, run for a couple of hours to top off the battery. Or, look at a Goal Zero Yeti (or equivalent), either to charge the battery or to directly power the CPAP.

Head spinning even more now? 😁

Sharon_is_SAM

What is SOFT?

rkj__

Dual 6V golf cart batteries will fit in the front tub with some rearranging. This will significantly increase your battery capacity.  A search of this forum for “golf cart” should bring u plenty of results. 

Depending how long you want to camp, and how much you can keep you solar panels in the sun, you might need a generator to recharge your battery bank. 

pthomas745

How are you monitoring your battery?  What do you mean by "dead?"  What is the wattage of your CPAP?

sranderle

I am a CPAP user and just switched to Lithium batteries after burning through a pair of 6v golf cart batteries (225 Ah) in 2 years.  The GC batteries simply will not hold a charge anymore.

While using the GC batteries prior to this year, I would run my CPAP on a 12v adapter specific to my unit.  However, I created a bunch of extra draw by running the humidifier and heated hose.  I had no way to know what my actual consumption was, just that overnight, we were down to 50% state of charge (SOC) or less.  The only other electrical draws would be the Fantastic Fan, and the fridge vent fans.

This year, I began using the CPAP without the humidifier and heated hose settings on, but still with water in the humidifier tank.  This seems to be working well.  We tried this twice before switching to lithium, and it didn't help with our dead batteries.  I also upgraded out Fantastic Fan.  On a warm night, we also add a 12v box fan, which I'm sure is not very efficient.

After I switched to a pair of LifeBlue Battery 125 Ah lithium batteries, I was able to see what one night of consumption really was.  So I dry camped in my driveway, running the ceiling fan at 50%, the box fan, the fridge vent fans, and my CPAP using my new dry setup.  After one night, my SOC had gone from 99% to 69% on one battery, while the other battery remained on standby.  The second night, the standby battery went from 99% to 70% SOC while the first battery went on standby.  If I convert this to Ah, one night's consumption for my scenario was around 37Ah.  When dry camping, we do not use any of the trailer's lights.  Instead, we use a Streamlight Siege lantern.

We will be going out this coming weekend to actually camp, and I do not plan on charging the batteries beforehand.  Once done for the weekend, I will then charge the battery bank back up and get an idea of how long it will take when SOC is around 40%.  It took 1 hour to charge each battery when I received them at a 75% SOC.  Charging time is one of the benefits to lithium batteries.  Over that last several years, we have always had to run a generator for several hours (2-6+) to get life back into our battery bank.  I'm looking forward to not having to do this every day.  I should also get some charge while towing.  

Oh, we do not have solar.  We bought a generator instead, since we like to camp in the forest.  

And now the downside to our solution.  Lithium batteries are expensive.  But for us, it was worth the investment for the ease of charging, greater discharge range, and full use of the Ah in the battery bank.  They will move with us when/if we switch RVs.

I hope this helps.

klenger

A generator may be the most direct and inexpensive solution.  Run it once a day and your problem is solved.

rkj__

klenger said:

A generator may be the most direct and inexpensive solution.  Run it once a day and your problem is solved.

If pulling 37 Ah per day or comparable, I’d still recommend a larger battery, in addition to the generator. 

Bayliss

@Kristi33, for whatever it is worth, I use a dedicated CPAP battery pack (made by Medistrom.)  I do not use the dehumidifier on my CPAP, so this battery pack usually gets me through two nights.  I recharge it using a generator when boondocking.  Although I have not yet had the need for it, I believe you can purchase a 12V cord with a cigarette lighter type adapter to recharge the battery pack while driving your vehicle (or from a similar charging outlet in your camper.)  I like the Medistrom, because it has an alarm that sounds if the available power is dangerously low.  Although I never use it, it includes a small flashlight.

Cbusguy

I have been on CPAP for about 20 years now and have tent camped for most of them.     Here is my advice from personal experience.

My setup is a philips respironics autopap I purchased the 12 volt power cord, cigarette lighter, to use while camping,.  I use a 12 volt 65 amp hour Duracell agm battery and have not run out of power over 4 night trips

1. Do not use your humidifier or heated tubing.  In helping other scoutmasters out I have seen these draw as much as 12 amps at 12 volts...

2. Do not use an inverter, to much loss in the conversion when you are trying to save power. Seen someone do that and exhaust a 100 amp hour battery over night.

3. How well does your mask fit?   Lots of leaks use more battery.

Are you running your refrigerator on 12 volt power?  Switching to propane is a huge power savings

How many times have you completely exhausted your battery?

How do you charge it at home or while parked?

When you park your trailer, is it oriented  to get benefit from your solar.  In direct sun and not under a tree.

These trailers have some parasitic power drains the easiest to address is the Jensen tv.   Unplug it.


These sorts of issues aren't a one size fits all.  The simple fix is to throw money at it with goal zero solar generators for hundreds of dollars or lithium batterys for thousands of dollars

Michigan_Mike

Agree, never use the humidifier or heated hose when dry camping.  Prior to buying the 400 T@B we use an ARB frig to allow for low energy consumption and to conserve energy I normally unplug it at night and wake up to 35° and no issues.  100 watts of solar will be hard to keep up with things and I have a 200 watt Zamp portable panel that allows for quicker battery energy replenishment if sun conditions allow for it.  

And I agree with others above, a small, quiet generator will provide security and that needed power should you need it.  Nothing worse than experiencing a dead battery and that anxiety and desperation felt from within when miles from home, in a remote area, knowing your CPAP won’t work and that a rough night lies ahead of you! 

rcuomo

Here's what works for us when boondocking.  I use a Harbor Freight 400w inverter and an Interstate SRM-27 deep cycle RV battery rated at 600 CCA, 160 RC (66.7 AH).  It will usually last at least 3 days fully charged using a standard ResMed machine.  I top off the battery daily using a Renogy 100w suitcase.  In full sunlight it will fully charge the battery in 3-4 hours, often in 2-3 hours. I also use a 1000w Xantrex inverter to power the microwave using the same battery.

https://www.harborfreight.com/400-watt-continuous-800-watt-peak-power-inverter-66814.html

kybob

My wife and I both use CPAPs. We use a Yeti-Goal Zero 400 lithium battery to run our machines at night when we don't have an electric hookup. With an adapter, the Goal Zero can be recharged while traveling or with our solar suitcase, or with our Honda 1000 generator. I chose the Goal Zero battery over the CPAP specific battery because it can be used to power other things, not just CPAPs.http://goalzero.com/ Look under portable power. Good luck!