Need advice on battery backup

[remstarcpap]

Hi,

Here in Silicon Valley we have offended the gods and the CPAP gods especially!

In the last three days we've had record hundred plus heat, two power outages of 12 hours or longer, and now fires and soon brimstone! LOL

Luckily I have an older Z1 travel CPAP with its little power shell battery so that got me through two nights without power. But it's only about nine hours of CPAP time per charge.

I wanted to figure out a better solution that would take care of at least three or four days in a row on a single charge.

Here are my questions:

I have a mix of machines. ResMed 24 V S9 and Air Sense 10. Respironics 12 volt System one and HDM Z1 Travel Cpap (12v).

1. Even though I typically use my S9, I'd be willing to use one of the other machines if it made it easier to do battery backup. The Z1 has its own one day battery, but as a CPAP is a little bit noisier and single pressure so I'd prefer to keep to using one of my auto machines. Is it significantly easier to use the Respironics 12 V system? I know that I would need a DC to DC step up converter if I wanted to use either of the ResMed systems. With the Respironics I would simply need something to adapt from the battery to the plug.

What would you guys recommend in terms of my emergency system, the ResMed machines or the Respironics System One?

2. What size battery should I get in AH? From the Resmed battery guide, it looks like an Airsense 10 takes about 1.0 amps per hour, so 8 amps per night. The S9 is lower, maybe 5.2 amp per night. I assume I should double these numbers to get the right AH per night, since I can only discharge the batteries 50%. So it looks like this:

Airsense 10 is 16 AH per night, so for three nights, about a 45 AH battery.
S9 10.4 AH per night, so about a 35 AH battery for three nights.
Not sure on the Respironics System One, maybe similar to the S9 around 5 amps per night.

So how to do the math? If I get a 35AH scooter battery, and don't want to drain it past 50%, then it seems like on the S9 with no humidification and no heat on the hose, I should be able to get a solid three nights before I hit 50%. On the air sense 10, I'm probably only going to get 2 nights. So that would lean me towards the S9 or the older Respironics machine.

3. I'm assuming the easiest solution is simply to buy a scooter battery, an AGM battery. What if I wanted to use lithium-ion batteries instead? I see a 20AH LIFEP04 lithium battery on AMzon for $189. Since this type of battery can be drained to 90%, is it reasonable to assume that I could get at least three nights out of this kind of battery? The battery is only six pounds.

4. If I don't need portability then would it be safe to assume LI batteries are a waste of money. I doubt that I will be camping with this setup.

Thanks for the input I appreciate it. This last few days have woken me up to the idea that I need to have a better backup system that doesn't depend on a generator.

[palerider]

1) whichever gives you the best rest, so probably, Resmed.
2) Sounds like you did the math. Add solar to extend usage indefinitely as long as it's sunny during the day.
3) see 4
4) sounds like you've got this figured out too.

[dreamingofdreaming]

I use a deep cycle marine battery from my husband's trolling motor when we lose power. I use high humidity and high pressure and slept for 8 hours with the battery recently when we lost power. Some in our town were without power for a few days recently. It had me thinking about getting a whole house generator.

[palerider]

I use a deep cycle marine battery from my husband's trolling motor when we lose power. I use high humidity and high pressure and slept for 8 hours with the battery recently when we lost power. Some in our town were without power for a few days recently. It had me thinking about getting a whole house generator.

There is no legitimate point in using a more expensive "marine" battery for the purpose of sitting around in your room. "Marine" batteries have no extra capacity, just extra cost because they are made tougher to handle the pounding they suffer on boats.

Just get a "Deep cycle" battery, like a mobility scooter battery.

[dreamingofdreaming]

I only used a marine battery because we had one in the garage. I would have taken the battery out of my car if it meant I could sleep.

[Pugsy]

I only used a marine battery because we had one in the garage. I would have taken the battery out of my car if it meant I could sleep.

Don't blame you one bit. You used what you had handy already. Smart economical choice.

The main point is that often people go out and buy a marine battery just for cpap usage and it's an unnecessary expense when that is the only reason a person gets a marine battery. If a person already has a boat and has a need for a marine battery that is one thing but if they don't there is no reason to spend the extra bucks just for "marine" in the name.

[klv329]

Sams club sells a 55ah deep cycle agm battery for $120, I think. The battery tenders at Walmart seem to work okay...the Schumacher tenders 2 batteries and Deltran 1.25 amp battery tender plus seems okay and claims to maintain 12v and 6v and auto-detects agm and lifepo4 batteries.

I keep a long 12 ft cigarette extension cable bolted to the battery with the tender, just to have some flexibility in battery location and so that it's ready to go without much effort in the dark. I use rubber bands to keep the resmed battery adapter secured to the cigarette receptacle because sometimes they separate when I least expect it to happen.

The lifepo4 batteries are really light but really expensive and are supposed to last a lot longer than agm batteries and have many more charge cycles. Ham radio types tend to like them for light, portable power, charged with solar panels, in their "go box".

Its good to have a battery tester, or at least test your battery yearly or semi-annually so you know when its not good anymore. Time flies, I just realized one of my 55ah batteries was 12 years old and it couldn't really hold a strong charge anymore so I use it for small electronics.

I also use the $10 resmed humidifier cover because I figure ill forget to turn off the humidifier all the way when I'm groping around in the dark and just wanna go back to sleep.

[remstarcpap]

So here's what I have bought so far, other parts are still coming.

Battery: Weize 12V 35AH Battery Rechargeable SLA Deep Cycle AGM $65

Battery Box: NOCO HM082BKS Group U1 Snap-Top Battery Box For Mobility And Lawn and Garden Batteries $11.36

Charger: NOCO GENIUS5, 5-Amp Fully-Automatic Smart Charger, 6V And 12V Battery Charger, Battery Maintainer, And Battery Desulfator With Temperature Compensation $55 on sale

Alligator to 12 volt accessory jack: NOCO GC017 12-Volt Adapter Plug Socket With Battery Clamps $9.94 This is fused.

Adapter for 12 volt to 24 volt for Resmed S9: KFD in Car Charger DC Adapter 3 Pin Jack for 90W Resmed S9 Series $33

This should get me up and running assuming the 12-24 volt adapter works. I'll report back.

Next steps: I'd like to figure out better connectors than the alligator clips. Any ideas? Ideally I would have wires permanently mounted on the battery terminals, that went to a quick connect plug that would switch between the Noco charger and a 12 volt accessory jack. The NOCO has some sort of proprietary jack, so I may need some NOCO parts. Also, what would be a good battery meter to install?

Thanks for the help.

[remstarcpap]

I found the NOCO interconnect cables, but have one more question.

Does it make sense to attach permanently to the battery eyelets BOTH the cigarette adapter, and the plug that will allow me to directly connect the NOCO charger. Or, would it be better to have a NOCO adapter plug that I would EITHER plug the charger into, or the cigarette lighter adapter?

[klv329]

I keep them both connected to the battery posts. Not sure if its the best way, but its convenient in the dark.