Solar Backup for CPAP Machine.

System · July 2008

Hey guys (and gals). First time poster, I depend on a CPAP machine to breathe correctly while I sleep as I have obstructive sleep apnea. I am a avid outdoors person and would like a way to run my machine while on camping trips with no A/C power at the site. I would also like piece of mind in the event of a hurricane where power may be out for days. My unit only draws about 15 watts when i leave the humidity heater plate off. It requires A/C power. I currently have it plugged into a APC Smart700 sinewave UPS. Upon testing the UPS runs my machine for about 6 hours before konking out so its not a viable solution (Its a 5yr old UPS). My insurance company will re-imburse me up to $250 dollars for supplies for an emergency backup power source (Including solar applications) I am willing to put in up to 250 of my own money if i can come up with a portable solar solution. Any suggestions or more info needed to help me find a solution. (BTW Im somewhat versed in the field of electronics/ amps/ watts, ect, but not much on solar power systms)

Thanks --Josh

FreeBrrd · July 2008

Re: Solar Backup for CPAP Machine.

Need to know how long it needs to run? Just 8 hours while you sleep?

If you only need it to run 8 hours / day & you have about 5 average sun hours per day (what I have in California).

I'm a newby too, but this requires similar to what I need so this is what I've found with the best prices / output:

Kyocera 65 watts $350.00
Deka 8A22NF $149.21
Morningstar SS-10 10 Amp $50.16
#12 AWG, 2 Conductor 25' $16.00 (minimum lenth sold)
shipping $35
total $600.00

plus a few connectors, fuses, etc.

this is all from Arizona Wind & Sun because with a bunch of research, they have the best prices. They also have really good customer service. Any answers I haven't gotten here, I've been able to ask them and gotten really quick clear responses.

If you need it to run 16 hours, you need all the same stuff plus another 65 watt panel, two more panels if it needs to run 24 / 7.

I'm sure someone will let us know if I'm incorrect here

System2 · July 2008

Re: Solar Backup for CPAP Machine.

Over kill is lots of fun, but how often do you need the backup is the important thing. In my case I added a deep cell battery to my pickup/car, bought a 700 watt inverter and a long extension cord. Works fine for me.
My CPAC is in use an average of 7 hours a night, which is what you have to look at. Solar cells don't do well in moon light, but a high amp hour battery will keep you alive. A car electrical system, believe it or not, is not designed to charge batteries, just maintain the charge. But for short needs it will work fine. I ran my house for 5 days off the truck, but paid the price later.

Good luck:cool:

mike95490 · July 2008

Re: Solar Backup for CPAP Machine.

Because you will be toteing this around, I'd suggest an AGM battery, sealed, but a few minutes of overcharge, and you fry it. Set your charge controller accordingly.
15 Watts (seems awfull "light") for 6 hours is 90 Watt hours. @ 12V = 7.5 A hours [for all night] Just a little bit of drain on the battery. Too little, did I screw up ??
A MorningStar Sure Sine inverter will give you nice clean AC, at about the best efficency in the class.

Mike

System2 · July 2008

Re: Solar Backup for CPAP Machine.

I called the manufacturer of my CPAP and they offer a rechargable 12v NiCD
8ah battery pack designed to run the unit for 5-6 Hours a charge and be recharged using a cigarette lighter adapter, and covered fully by my insurance. I didnt have power for 9 days after hurricane Rita in '05, and running the vehicle for several hours to charge a battery may not be an option if gas is scarce after a storm. I also want solar since its quiet to run on, say a camping trip. If its not feasable I understand but I thought it might be a good alternative to a gas generator for my modest needs.

niel · July 2008

Re: Solar Backup for CPAP Machine.

5-6hrs isn't going to do you much good as it will run out of gas before you're done sleeping. if they offer access to a larger battery pack then go with it. if they do offer larger packs then get 2 as this could be charging one pack while the other is ready to use no matter if by solar or whatever power sources you'll have to charge it. if they have a provision for connecting external 12vdc then that makes it real easy to place a larger 12v battery and you can then set that up for proper recharging with either solar or a quality 120vac charger.
as to using the modsine inverters on something like this i'd advise against it as that would minimumly cause the drawing of more power than necessary and could shorten the life of the unit as it dissipates more power. 15w does seem mighty low and no matter what due to efficiency percentages you will need more than 15w anyway. if you must have a 120vac inverter to it then try to get a small sinewave inverter. they are much more costly, but far cheaper than having to replace your cpap machine.
a thought here, can the unit run while the battery is being charged? if it can you may have an answer to your small battery dilema through the auto adapter from a 12v battery that has more current available depending on the number of nimh cells in the battery pack.

System2 · July 2008

Re: Solar Backup for CPAP Machine.

For car camping I've used an 80ah deep cycle battery ($60 at Costco) which keeps my CPAP powered for over a week (at some risk of sulfation). I'll probably add a 40-60W solar panel next summer to keep it topped off.

If weight is a concern: BatteryGeek.com markets a 4lb, 220Wh Li-Ion battery pack for CPAP use. A bit pricey at $400, but the light weight means backpacking is an option.

Redford · July 2008

Re: Solar Backup for CPAP Machine.

I think it's batterygeek.net......the one you listed is a redirect to a bicycle racing site (batterygeek.com) FYI.

They have one Li pack that is 444wh of capacity which might be enough for a couple nights.

mike95490 · July 2008

Re: Solar Backup for CPAP Machine.

agt wrote: »

For car camping I've used an 80ah deep cycle battery ($60 at Costco) which keeps my CPAP powered for over a week (at some risk of sulfation). I'll probably add a 40-60W solar panel next summer to keep it topped off.

That should work, if your unit really only draws 15w

System2 · July 2008

Re: Solar Backup for CPAP Machine.

5-6 hours of CPAP a night is better than no CPAP. I double checked and with just the air pump running it draws 15-17 watts according to my UPS power monitor software. If i get 2of the the 8ah NiCd batts the manufacturer offers, how big of a PV panel would i need to recharge atleast one of them everyday everyday. Also my understanding has always been NiCd's can be discharged fully without damage (ie: like in the solar garden lights). Thanks again for you alls help. --Josh

BB. · July 2008

Re: Solar Backup for CPAP Machine.

It all depends... Assuming you are camping/want emergency backup for 9 month of the year around Louisiana... And you are using an Off-Grid system with battery backup, and an inverter to charge your NiCAD battery pack. Using this link with all set to default (except use derating of 0.52 to account for all of the losses), 20 watts * 8 hours per day, around Baton Rouge using this link (I have to use 1 kW worth of panels, because the program will not accept anything smaller--just multiply by a scaling factor to get the actual panel size required).

1kW of solar panels will generate 9 months of the year around 60kWhrs per month (or more) or 60/30=2kWhrs per day.

20 watts * 8 hour = 160 watt*hours

(160 watt*hours / 2,000 watt) * 1 kW of panels=0.08kW or 80 watts of solar panels...

This sort of assumes a pretty "lossy" system... You are charging lead acid batteries from solar and then running an inverter to charge your NiCads through their dedicated AC charger... If you can find a good charge controller to charge the NiCADs (what is their charging voltage perhaps a programmable SunSaver MPPT from MorningStar may work) directly from the solar panels--you might be able to reduce the panel size down to 50 watts or so...

Lastly, NiCads do discharge down to zero volts pretty well (should avoid making it a habit--if you can)... But what usually kills them--for example you have 12x 1volt batteries in a string... Each holds 10 amp*hours, except one weak cell which holds 9 amp*hours... As the pack is outputting voltage/current/energy--it humms along just fine at 12 volt output, and decaying to 11 volts--but that is 11x cells at 12 volts and one (weak cell) at 0 volts. And that battery is actually reversed charged by the other 11 cells. And that ruins the one cell--and ruins the whole pack (if you cannot replace the one bad cell).

With multi-cell rechargeable battery packs, it is very hard to tell from the out slowing falling due to all cells being discharged vs one cell being reversed charged... From what I understand, you can buy "matched" strings of cells battery packs that model R/C racing cars use--This helps avoid one cell being reversed charged as all cells have had their capacity measured individually before the cells have been assembled into a pack.

-Bill

niel · July 2008

Re: Solar Backup for CPAP Machine.

using the packs that only supply power for 6hrs i'd say don't bother with 2 of them unless they could be paralleled. it doesn't make sense to interupt one's sleep to switch battery packs to go back to sleep. that's akin to what hospitals do when they wake you to take a sleeping pill. if the leadacid battery will keep that cpap machine going, then go with it.
if going with a larger leadacid battery and you can't swing the costs of solar right away then by all means use a quality battery charger that runs off of utility power and add the pv and controller later. you may even wish to expand on this backups thing as in no power for you fridge or lights will exist either, but i realize that expansion won't be medically covered.

mike95490 · August 2008

Re: Solar Backup for CPAP Machine.

Spotted this today, looking for goodies for my CPAP. Problem is, they seem to be the ONLY vendor carrying this item, and I have no way to judge it, or who the actual mfg is.
islandwiderespiratory.com/150_watt_sine_wave_inverter.aspx
www.batterygeek.net/product_p/150_watt_sine_wave_inverter.htm
Supposed to be high enough quality to use with CPAP equipment

boB · August 2008

Re: Solar Backup for CPAP Machine.

I think it was a Samlex 300 Watt sine wave inverter that I used once for my CPAP on a camping trip.

This 150_watt inverter looks pretty cool too.

What I wanted to make or design I guess was a portable CPAP that
ran on running river water... Just sleep next to a river while hiking and
drop this water powered air pump in the water. You'd need a longer
air tube though but it would be fairly light weight and wouldn't need
to hike in a heavy battery.

boB

niel · August 2008

Re: Solar Backup for CPAP Machine.

i'd be a bit leary about it as they spec'ed 50hz at 110vac. it may be a misprint, but who knows as one can't just keep searching for the manufacturer as it implies they manufactured it. it may be better to contact the cpap machine's manufacturer and ask them what they recommend(that is if they ever even thought of this circumstance). as far as i'm concerned any of the sinewave inverter manufacturers dealt with here for solar should work with such equipment, but if only for that cpap machine then a low power rating should be employed that covers the power requirements of that machine. battery operation would be more ideal if it's practically feasable to use it on his machine.

niel · August 2008

Re: Solar Backup for CPAP Machine.

boB,
wasn't it difficult to carry the cpap and its battery through the woods? i don't know what brands or models you guys have, but my old respironics draws nearly an amp at 110vac. yes, boB, i have sleep apnea too as diagnosed in jan '07.

mike95490 · August 2008

Re: Solar Backup for CPAP Machine.

mike90045 wrote: »

Spotted this today, looking for goodies for my CPAP. Problem is, they seem to be the ONLY vendor carrying this item, and I have no way to judge it, or who the actual mfg is.
islandwiderespiratory.com/150_watt_sine_wave_inverter.aspx
batterygeek.net/product_p/150_watt_sine_wave_inverter.htm
Supposed to be high enough quality to use with CPAP equipment

_______________________

MOD-SINE wave:

from the vendor:
The 150 Watt Sine Wave Inverter with USB Charger Port has a Modified Sine wave. It's output frequency is 60Hz. They are in stock and we have had mostly positive feedback. The only bad was that some people were confused as to how to operate it (there is a pin on the bottom that opens up the input. Some have found it difficult to locate).
Should you have any further questions or need, do not hesitate to contact us.
Ed Heavey Island Wide Respiratory, Inc. Staten Island, New York 10314-3521

boB · August 2008

Re: Solar Backup for CPAP Machine.

niel wrote: »

boB,
wasn't it difficult to carry the cpap and its battery through the woods? i don't know what brands or models you guys have, but my old respironics draws nearly an amp at 110vac. yes, boB, i have sleep apnea too as diagnosed in jan '07.

Niel, this was not a hike on this camping trip. We were in a tent right next to a car at the Sol West energy fair in John Day Oregon.
But I think it would be neat to have a water powered unit. I think I have a Respironics too.

boB:D

niel · August 2008

Re: Solar Backup for CPAP Machine.

ok i understand now. it would be easier to pv power that than with water i would think. do they make very small hydro generators as i've never seen one that is small and portable, let alone a paddle-wheel design? the long air tube would be a problem for sure.

boB · August 2008

Re: Solar Backup for CPAP Machine.

I wasn't even thinking electric. Just hydro to pump the air.
Electricity is too "heavy" for hiking I think.

boB

niel · August 2008

Re: Solar Backup for CPAP Machine.

you won't need the cpap machine then if you're pushing air with the hydro, but some air pressure regulator would be needed or you may blow up like a balloon.

if the stream is not strong enough for the design that could be a problem as well as being near water every time.

mike95490 · May 2011

Re: Solar Backup for CPAP Machine.

wakening up this old thread for an update.

OK, I wussed out, and bought a commercial product! We have a small sleeping hut built on the ranch now, but no power in it yet. It's going to take a while to mount a panel, batteries, charge controller, wire up lights and such, and we arrive at nighttime, and no where to plug the CPAP in ! So I spent a couple days pricing out different ways to accomplish this, and settled on a portable jump start pack. Found a model with good reviews, and no air compressor (that often fails after 50 total minutes of use). Located one in stock at local autoparts store, and bought it, taking a chance it's been parked in a warehouse for a year, and then in the back room for 2 more years, resulting in a flat, sulfated battery. (fully half of the complaints at Amazon)

Other choice was to get a AGM battery, rig up a case, cigar jack outlet, charger and hope it still fits into the car.

Upon opening it up, and throwing a voltmeter on it, I was pleased to find it reading 12.85V on a warm afternoon. It's built-in indicator showed it was 4/5 charged - also good. I plugged it's wall wart (transformer, not switcher, 12V, .5A) in, and let it top it off for a couple hours, it came to quiescence at 13.37v, and I unplugged it. After an hour, it read 13.13V. Awesome! And the Respironics power cord appear to fit snugly into the lighter jack.

Using my kill-a-watt before I was shopping, I'd discovered that the CPAP consumed about 75 watt hours in a 6 hour run, and that for 2 nights, I'd consume about 12.5 ah of battery. The "450A packs" claim to have an 18AH AGM battery in them, but I figured, I may as well have a portable unit, than a hulk that will last me a month. And if I only ran it one night (6.25 AH consumed) and then recharged, it'd live a long lifetime. Well, the power brick for the CPAP is a pig. After running all night (6 hours) , the voltage in the AM, read 12.66v Whoo hooo! Internal battery indicator LEDs still showed 4/5 charge, way less drain than the power brick used (all my testing is done with humidifier OFF) so even though the brick read about 3 watts idle, it was using more with a light load.

So, this will recharge at my shop, and I think I'll get a plug in lamp timer, and set that for a 1 hour charge daily, to keep it topped off between visits. And since the shop is on solar power, now my CPAP is too!

Added benefit, the power pack has a LED lamp built in, and a USB power port, so I don't even need a cigar plug Y cord to charge my phone and PDA.

So, I've owned this less than 2 days, but I think it will do the job I need it to, and it's not DOA out of the box. It can also charge via a running car too, but I've not tried that yet, I think I can also feed it from a 3 stage charge controller set for AGM. And it can jump start the tractor too, if I need it.

And it was a lot less than the $$ soft side 14ah CPAP battery pack. I hope the AMA does not come after me!

Solar Backup for CPAP Machine.

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