Back up battery/generator for BiPap

[Aggie]

Could someone please tell me what Back Up Battery or Generator for a BiPap I should purchase.

[chronic]

I keep procrastinating doing this, but, my idea is to purchase the appropriate connectors off of Amazon. Both together are about 40 bucks. Then, buy a cheap but adequate battery from my favorite Wallys World for about 70 bucks. I already have a couple of trickle chargers so that is all you need I think. Nothing fancy. Emergency use only.

[srlevine1]

I keep procrastinating doing this, but, my idea is to purchase the appropriate connectors off of Amazon.  Both together are about 40 bucks.  Then, buy a cheap but adequate battery from my favorite Wallys World for about 70 bucks.  I already have a couple of trickle chargers so that is all you need I think.  Nothing fancy.  Emergency use only.

Are you prepared to give up humidification and the use of heated hoses? 

Remember the DC-DC Converter from ResMed and the necessity of purchasing a "deep cycle" battery that can withstand deep discharges. Non-lead-acid batteries of sufficient capacity are not cheap, and you may need a special charger for the type of battery purchased. 

And there is the issue of the battery possibly outgassing flammable hydrogen while under charge. 

Bottom line: easier said than done.

[chronic]

reply to: srlevine1
Yes, I would turn off the humidifier, but, leave a little distilled water in it. I have been on these infernal machines since 2004 and never felt the need for a heated hose. I have 2 though. Remember this is an emergency, temporary use only. I would do my battery charging in garage. If I am real lucky I can keep the battery in the garage run the wire from there to the cpap inside with me. Supposed to be 12 ft long. I have not bought anything yet. I just don't believe everything I hear or read. As for the resmed converter, that is what comes from Amazon, look it up. Won't break the bank!!

[chronic]

I just took a look. Both connectors together are near 20 ft, plenty enough to keep the battery outside!!!!

[Aggie]

Wow! Thank you for the advice. I would only need it if the power went out in my house, like it did last week. This is not a cheap or easy fix is it?

[robbob2112]

My solution - this setup mounts inside a plastic file holder I got at goodwill for $2 - here is the design and layout

The charger is outside the box so it has ventilation air - it is fairly loud so it is plugged into a wall timer and it runs when I am not in the room.  I choose a 20amp charger mainly for the metal case and the fan.  I started with a fanless 10amp charger in a plastic case and after a week it had melted the case.

Buy cables pre-made from windy nation or battery cable USA.

This will run for 4 consecutive nights with the tank humidifier on and the tube heat on for 10 hours a night.
UNLIKE lead acid batteries the LiFePO4 batteries do not OFF-GAS anything when charging
Total weight is about 22lbs....  Between the higher capacity than a deep cycle and lower weight it is worth every penny.


Pros - 
Weight - 22lbs total
Duration - 4 nights verse 1 night
Heated hose and humidifier on instead of OFF
Longevity - last 10 years with minimal degredation - 

Cons - 
Cost - sorta - this lasts 10 years verse 3~5 for lead acid.

Parts list:

battery - $299 - you can get cheaper, just make sure it is quality
https://www.amazon.com/Litime-LiFePO4-Ba...B0BX8S2VJ5
Charger $89
https://www.amazon.com/Lithium-Battery-C...B08PZ7LBT6

MANDITORY- do not skip this type fuse for a generic automotive, the LFP battery puts out higher current when shorted.
Fuse with holder$16
https://www.amazon.com/BOJACK-Terminal-M...B0CHJN41TV
You need to be able to turn it off.
Switch $14
https://www.amazon.com/gp/product/B0B17BGHPS

Sub-total - $418

Optional - pick one - battery monitor
round $37
https://www.amazon.com/gp/product/B07FGFFHC6
rectangle and a bit more info - $59
https://www.amazon.com/Motorcycle-Backli...B0C6K4J7Q4


I run off the resmed brand 12v adapter to avoid the losses associated with converting back to AC just to have to convert to DC

[SleepyStreets]

This is very accurate, I just finished testing with my battery backup solution last night. 

I got the Medistrom24 battery (thank you insurance), I know it is supposed to be used without heated hose and no humidification, but I was curious so I left them on. I also to be honest wasn't sure how to turn both off and didn't want to mess around with the settings to much. From fully charged I lasted around 3 hours, I was kind of disappointed with this result to be honest. 

I had an old UPS battery (100Ah) sitting in my garage (was being tossed out at work but it seemed okay enough to me), so I built a case for it out of wood. I then added a couple 12V sockets on it, then found some small solar panels (I would like to be able to get it so I can take it camping for a week or so). I got a ResMed (to AS11) cable and hooked it all together. 

With heated hose and humidity turned on I slept 6:28 (Sunday), 7:06 (Monday), 6:42 (Tuesday), 7:42 (Wednesday), and about half an hour before it died last night. 

My only issue is that this setup weighs around 75lbs   

I plan to get it charged back up and see how these results change without heated hose, then without humidification, then without both.

[srlevine1]

@robbob2112

Well Done!

[robbob2112]

I forgot a couple of things -

With heated hose and humidifer it consumes 260Wh (Watt Hours)
Without it consumes 70Wh.

100Ah LiFePO4 (LFP) battery at 12.8v
100Ah * 12.8v = 1280Wh.

Can safely use 90% of this capacity
1280Wh * 0.9 = 1152Wh
1152Wh / 4 = 288Wh

So the math pretty closely follows reality.

MediStrom Pilot–24 Lite Battery has 95Wh of capacity - I would expect it to last 2.5 to 3.5hrs depending on how your settings are on the CPAP - higher pressure means more power used.  Uses LiPo batteries.

SLA (sealed lead acid) - and AGM -  to avoid damage you only use down to 50%.  You can use 100% of it maybe 50 times and it will fail to take or keep a charge.  Each time it takes more damage.  In any case the batteries have a total of about 300 cycles to 50% or 3 years and they are done, if they are charged to fast or overcharged it is more like 2 years.  Some VERY expensive ones can be used 100% repeatedly and they have a 10 year life.  Can get is nearly any size Ah.

FLA (flooded lead acid) similar rules to SLA and life except the there are no 10 year versions.

LiFePO4 - 3000+ charge cycles, 10 year life before degrading, 15 year life with 10% degraded.  Unlike LiPo they won't burst into flames sponkaniously when damaged.  If they are damaged they do vent hydrogen so that can catch, but it requires an ignition source.

Assuming your 100ah UPS is in good shape with new batteries you can do the math and guess how it I'll come out.

Can attach a SCC (solar charge controller) and a couple of solar panels and no need to plug in.


One note - the LFP batteries shouldn't be stored or kept at full charge, so I run it down by 25% nightly and it recharges daily.

I have been using this for 6 months now.