Hello Guest, Welcome to Apnea Board !
As a guest, you are limited to certain areas of the board and there are some features you can't use.
To post a message, you must create a free account using a valid email address.

or Create an Account


New Posts   Today's Posts

Running on LiIon Batteries?
#1
Anyone have a good idea about how much power a PR Systems One draws without the humidifier or a heated tube? I've got some nice 18v LiIon drill batteries and some friends who are Electrical Engineers, and was thinking about trying to make a portable power pack from them for camping instead of spending $300+ on a 3rd party premade pack.
Post Reply Post Reply
#2
More work than it's worth... and a waste of time, too. Typical tool packs are about 2AH... just enough for a short nap. Buy a $50 battery, do a direct connect that doesn't require finicky LiIon chargers, and have a night or two in reserve. Spend $75 and you'll get three to four nights. $400 will get a DIY nearly two weeks online - longer if you don't mind a bit more maintenance.
Post Reply Post Reply
#3
The PR System ONe Auto (560) draws about 0.3 amps for me at an average of 9cm pressure with no heated humidifier. I can get a week or more off of a 35 AH battery.

There are some newer LiFePO4 deep cycle batteries out there now that are 9-10 AH that are laughably light weight and are fit into the same size case as a 7 AH SLA battery. I would expect, at my pressures, of getting at least two nights out of them, conservatively. I would seriously consider those if I was going camping. Even better if you have a source to charge them in the day.

LiFePO4 is Lithium IRON Phosphate - not what you typically see as "Lithium Ion".

If you want a direct reference, send me a PM.

OMMOHY
Post Reply Post Reply


#4
Thanks OMyMyOHellYes.

I looked at the power supply, and it's rated at 60 watts (for both the humidifier and PAP unit.) That translates into 0.5 Amps. I'm guessing your draw numbers are right then, as the heater in the humidifier must be a fairly serious draw.

That means for a weekend camping trip I'd need at least 5AH (0.3A * 8hrs * 2 nights = 4.8AH), probably closer to the 10AH you state for safety. It seems that the battery pack ratings aren't straight forward though, so 10AH LiFePO4 battery pack may not actually have 10AH of energy in it, but provide an equivalent cranking power as a 10AH lead acid, which doesn't mean jack in my application.

If I can find a way to charge (solar panel?) it might be able to make a longer trip.
(06-03-2015, 02:36 PM)GWild Wrote: Buy a $50 battery, do a direct connect

A standard size battery isn't going to fit in my Kayak.
Post Reply Post Reply
#5
I just looked at one of these in a 100AH capacity. Only $1,000.00. If the sales/marketing claim is true, 2000 80% cycles at 100A, they'd be pretty amazing. Still looking for a real spec sheet though... until I see that info, everything else is smoke and mirrors.

Wow - I found one, 12V 26AH ... and I am impressed ... but dubious:
   
Post Reply Post Reply
#6
No, do not confuse the LiFePO4 starting batteries with the LiFePO4 deep cycle batteries. Two different things. The starting batteries as you say are not for crap for this purpose. if it has an "AH equivalent/PB equivalent" rating, move on - it's a starting battery. Googleate "LiFePO4 deep cycle battery" and "LiFePO4 SLA equivalent" to find what I'm talking about. The ones I found that were recommended were by CTC or K2 Energy.

OMMOHY
Post Reply Post Reply


#7
I did do that - the curve above is for an extended use battery - and a 100% discharge at 1750 cycles with 80% capacity remaining is fundamentally awesome.

I did find a few more references, and if similar designed batteries are held to 30% DoD, the expectation is over 8,000 cycles. Those plots didn't say whether end of life was 80% or the more common 60% of original capacity... either case is good news. Now if they could just get the costs down.

As an aside, I found a 20AH battery with charger for $225. A 30AH for a bit more. Weights of 8 pounds for the larger. So there's hope these will become mainstream.

ps: I am dubious on the 0.3 amp number. When I measured my 550P to select my battery, it was closer to an average of 0.8 amps over 8 hours... or 6.4AH per night. Perhaps I'll do the exercise again as I add the 560P plug to my kit.
Post Reply Post Reply
#8
(06-04-2015, 03:03 PM)GWild Wrote: I am dubious on the 0.3 amp number. When I measured my 550P to select my battery, it was closer to an average of 0.8 amps over 8 hours... or 6.4AH per night. Perhaps I'll do the exercise again as I add the 560P plug to my kit.

Okay, I made a mistake with my calculations above: the power supply is a 60watt DC power @ 12 volts, which is equal to 5A, not 0.5. I used 120v instead, which is the supply side voltage. The one with a heated hose has an 80watt power supply, which is 6.6A. I'm guessing the power supplies are SEVERELY overrated though.
Post Reply Post Reply
#9
(06-05-2015, 09:29 AM)lmoretti Wrote:
(06-04-2015, 03:03 PM)GWild Wrote: I am dubious on the 0.3 amp number. When I measured my 550P to select my battery, it was closer to an average of 0.8 amps over 8 hours... or 6.4AH per night. Perhaps I'll do the exercise again as I add the 560P plug to my kit.

Okay, I made a mistake with my calculations above: the power supply is a 60watt DC power @ 12 volts, which is equal to 5A, not 0.5. I used 120v instead, which is the supply side voltage. The one with a heated hose has an 80watt power supply, which is 6.6A. I'm guessing the power supplies are SEVERELY overrated though.

No - I don't believe the supplies are overrated ... my machine has drawn 25 watts at times... and pretty sure it wasn't at max pressure and volume.

These were peak currents while in use, and the average is certainly less, but the brick supply has to handle the peak currents otherwise the machine would stop working.
Post Reply Post Reply




Possibly Related Threads...
Thread Author Replies Views Last Post
  Finally up and running with Sleepyhead skylark 3 163 10-08-2017, 08:18 PM
Last Post: skylark
  sourcing batteries for Transcend, preferably generic bunter 23 3,797 07-18-2017, 10:17 AM
Last Post: IBEW292
  Would 2 12V batteries in series avoid need for Resmed''s (A10) converter 2SleepBetta 1 274 03-16-2017, 09:39 PM
Last Post: Sleeprider
  [CPAP] Calculatur for S9 on 12V batteries nilsola 7 1,043 12-06-2015, 02:08 AM
Last Post: nilsola
Thumbsup SleepMapper is up and running! [Philips-Respironics software] Hdowning 49 36,455 11-16-2015, 07:46 PM
Last Post: jpsgt2
Exclaimation [Equipment] Wearing mask without running the machine DeepBreathing 10 1,991 09-19-2015, 11:18 PM
Last Post: Jim Bronson
  Spoke with ResMed, got cable info for both batteries. Double checking with you. JVinNE 20 4,309 04-17-2015, 08:27 PM
Last Post: justMongo

Forum Jump:

New Posts   Today's Posts




About Apnea Board

Apnea Board is an educational web site designed to empower Sleep Apnea patients.

For any more information, please use our contact form.