A deep cycle AGM battery is always going to be the best bang for the buck and they don't leak battery acid if you crack the case. If you don't need a humidifier, CPAP machines don't pull a heck of a lot of power. 1 amp at 12 volts is a pretty good rule of thumb to run the blower motor. If you use resistive heat to run the humidifier or heat the hose, it can easily be 5 or 6 amps at 12v. I see an 18 amp-hour ML18-12 AGM battery with free shipping for $34.99 on the large internet retailer's site. It weighs 11.9 pounds. I have the 35 amp-hour version of that battery but it weighs 25 pounds. Lithium is always going to be much lighter weight but you pay a lot for it.
Thanks much for the helpful advice.
I did not say much in the post about solar, but when I made the mistake Mongo noted, I bought Anker's solar panel, which I think should be adequate. As for an inverter I wasn't planning on using one if I could avoid it.
The battery in the canoe that is an interesting idea I had not thought about. There are two issues with that. One is weight. My canoe is a 1935 Old Town and weighs 110. You also want bow and stern perfectly balanced on portages, that way you can carry no hands on long portages.
That is a really good price. I have to admit the weight/price issue is probably up to each person. I have seen people portage lawn chairs and once even found a mattress on a camp site, so eight pounds isn't bad. It is about the weight of a three person tent.
On the other hand there is a part of me that goes back to the days when backpackers cut down toothbrushes to cut weight. Canoe campers can get away with more weight than backpackers, depending on the trip. But my aim was to try to build a thread for anyone doing wilderness tripping. Like I said before, if you get a few days in and your CPAP rig does not work there is not much you can do.
As for weight the law of compensation holds. You can always cut something else to accommodate the eight pounds.
It sounds like from what you said the battery would charge with a solar charger as per Sleepster's advice. Clearly I will need to do more research, but anything you want to add would be helpful.
Thanks to everyone for the help and, yes, my idea was to try to get all the info in one place so it could help others. I believe in giving back so I will try to do my best. At some point I will post a summary and then you folks can have at it so we have at least the start on a source. Then new people on the forum or people looking for advice can go on from there.
One idea: it seems the weight/price issue drives many of the discussions. So perhaps that is the way to organize it. You could have a matrix with one axis being weight and the other price.
I apologize if I was too critical.
06-20-2015, 05:08 AM
(This post was last modified: 06-20-2015, 05:17 AM by OMyMyOHellYes.)
Do a little research on the LiFePO4 SLA replacement batteries - not the starting batteries like the Shorai motorcycle batteries - but the newer deep cycle ones - some that I have seen that are getting better reviews are by by CTC or K2 Energy. They are supposed to have built in BMS (battery management system) controllers that help keep the cells balanced which can be a real issue with this technology. There are cheaper ones, but you know what they say about getting what you pay for ...
I had hoped to be able to buy and test one in this application, but due to an interruption in income, I have been unable to do so. So this is theoretical discussion on my part. But These things are lightweight.
BTW - - for those of you who are experimenting with ResMed, that 3 prong plug is available.
It's a KPPX-3P
INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.
Will look into the LifePo.
A couple of questions. What is the minimum ah rating on an SLA that is ok for CPAP? What is the ideal?
Second question concerns labeling...It appears SLA batteries that look to be identical from the same manufacturer are packaged as alarm batteries, scooter batteries, etc. depending on what they are packaged for the price changes. Any reason for this? I assume it does not matter for CPAP.
My idea is to cover SLAs by listing the minimal ah with price and weight, the preferred and the max.
Would do the same for LifePo.
Everyone wants it fast cheap and easy. Life seldom works that way. I paid a $grand out of pocket to get what I needed Fast. I did not like it but my health was paramount to me.
Your idea of a decision matrix is great and I hope you follow thru. I wish to return to living on a sailboat. Amps and to an extent weight are precious on a sailboat. I get it. At one time there was noise of a propane burning fuel cell for laptops. Something like that would have much better watt density than about any battery. Someone in a camper might have a small $100 genny or even a bicycle style generator. Pedal during breakfast and get ready for the next night
I use my PAP machine nightly and I feel great!
Updated: Philips Respironics System One (60 Series)
RemStar BiPAP Auto with Bi-FlexModel 760P -
Rise Time x3 Fixed Bi-Level EPAP 9.0 IPAP 11.5 (cmH2O)
06-20-2015, 09:55 AM
(This post was last modified: 06-20-2015, 09:58 AM by Oldguide.)
Your comment about charging technologies brings up the Power Pot. It is a cooking pot that also generates electricity. As far as I know they currently come with only USB connectors so they would not work for CPAP.
Here is what I have learned about LifePo4. It is being touted as the next big thing in solar battery storage.
Advantages over conventional lithium:
It last longer over the life of the battery--a lot longer.
It is safer: less prone to fires, overheating, damage from dropping it, etc.
Works with solar if it has battery system management. This is a must for this type of battery.
Disadvantages are that at least one vendor will not let you return it. On the other hand if you research K2 you will find it is probably sold by some local vendor. To find a vendor go to the manufacturer's web page or look for LifePo4 prices on a search.
BTW K2 is made in the U.S.
Here are some sample prices I found. Please do not treat them as definitive. Note the LifePo4 batteries are cheaper than the dedicated lithium batteries sold by CPAP vendors. They are comparable to the Bix and Anker batteries mentioned in an above post.
Note the LifePo4 batteries come just with terminals. No kits of DC tips. Battery Tender has a connection system but you pay extra for it. This may be a place for DIY folks if you know your wiring (inside of DC plug is hot, outside is neutral/ground.
So here are the prices:
12v. 10ah $159
OTHERS. BATTERY TENDER
12v. 10-14a $95 1.8lbs
12v 16-18ah $159 2.1lbs
12v 24ah $150 2.8 lbs
If anyone has different ranges/manufacturers jump in.
06-20-2015, 10:54 AM
(This post was last modified: 06-20-2015, 11:00 AM by Starrbelie.)
Thanks, Oldguide, for sharing what you have learned. I'm still not sure what set-up will be my best compromise. Some of the options weigh more than my yak and certainly cut into my weight capacity quite a bit! Others cut into my money capacity quite a bit, costing more than I paid for all my gear combined, yak, paddle, life jacket, and hammock! Thankfully, my OSA is mild so, for now, I'll just do without CPAP on my excursions.
I did see a place online that rents batteries for CPAP (Google "solar batteries for CPAP for rent"), that might be an option for you until you can sort out the best set-up for you.
Add a few more to the LifePo4 list:
Tenergy makes an interesting gizmo called the Sidekick which is rated at 13.6 ah. It is marketed as an emergency device for storms. Has a flashlight, spotlight, emergency light and will start your car. Has a slick little kit like a wallet that holds the device plus a bunch of tips, etc. Price: $109.
CTC has a 12v 10 ah for $129
I hear you. Unfortunately that option is not open to me. When they did my sleep study I had over 400 instances when I stopped breathing in four hours. The longest was between 20 and 30 seconds.
(06-20-2015, 06:34 AM)justMongo Wrote: BTW - - for those of you who are experimenting with ResMed, that 3 prong plug is available.
It's a KPPX-3P
Which pin is hot, and which is not, and what is the "signal" on the third pin? Is it a digital signal or just a little current that might be tricked by applicaiton of some juice running through a resistor or set of resistors to get a certain voltage that would allow the main stuff in (kind of like a radio repeater squelching incoming traffic unless the sender is also broad casting a PL tone)?