Battery Advice

[Dog Slobber]

I'm interested in a battery backup up solution, primarily incase of a power failure.

I've read the Choosing a Battery topic ( viewtopic/t114012/Choosing-a-Battery.html ) and hope I understand it properly. The topic focuses on lead-acid, while it does mention lithium, most of the measurements are based on Amp Hours (AH). The consumer based Lithium battery power stations are typically measured in Mah and or Wh.

The Battery I'm looking at specs are:
AIMTOM Portable Solar Generator, 42000mAh 155Wh Energy Inverter Supply, Emergency Backup Battery Box with Flashlights, Power Station for Camping, Home Use, CPAP, Travel, Car ( 110V/ 100W AC Outlet, 3x 12V DC, 3x USB Output )

https://www.amazon.ca/dp/B0791Y1WSQ

Is the 42,000 Mah, 155Wh equivalent to ~13 Amp Hours at 12 volt?
(155 / 12 = 12.92)

Assuming its capacity is 13 Ah, looking at the ResMed battery table from their battery guide:

Battery_table.png

My AirSense 10:

• Pressure 12 cm
• DC powerbar
• SlimLine (no heated hose)
• PassOver Humidity

Should give me at least 8 hours, with the built in 50% safety margin?

My calculations are:
13 (Ah) / 1.06 (amps) = 12.26 (Hours)

And the 50% Safety Margin is 8 hours.

Does anyone use any of these Lithium Power Stations and have any thoughts on their actual performance?

[palerider]

I'm interested in a battery backup up solution, primarily incase of a power failure.

I've read the Choosing a Battery topic ( viewtopic/t114012/Choosing-a-Battery.html ) and hope I understand it properly. The topic focuses on lead-acid, while it does mention lithium, most of the measurements are based on Amp Hours (AH). The consumer based Lithium battery power stations are typically measured in Mah and or Wh.

Wh is the thing to compare, in the battery topic, he's talking about lead acid, and you should multiple AH by 12.6 to get Wh, so a 35AH scooter battery gives you 441 Wh.

the lithium stuff is marketed by shysters. quoting things in milli-amphours (which is thousandths of an amp hour) so they say 20,000! mAh.. because that sounds so much more impressive than 20 Ah. PLUS, they typically are talking single cell lithium voltages, or about 3.6v, so that 20,000! mAh lithium doodad works out to .... 72 Wh. weee.

The Battery I'm looking at specs are:
AIMTOM Portable Solar Generator, 42000mAh 155Wh Energy Inverter Supply, Emergency Backup Battery Box with Flashlights, Power Station for Camping, Home Use, CPAP, Travel, Car ( 110V/ 100W AC Outlet, 3x 12V DC, 3x USB Output )

https://www.amazon.ca/dp/B0791Y1WSQ

Is the 42,000 Mah, 155Wh equivalent to ~13 Amp Hours at 12 volt?
(155 / 12 = 12.92)

give or take.

The scooter battery/charger/12v cable is the cheapest "hours of use per dollar spent" solution, by far. it's just not small and portable.

Like, you could get *two* scooter batteries, and a charger for less than that 'solar generator' (not a generator, more marketing wank) and get *10 nights* out of it.

[Dog Slobber]

Thanks for that.

Did some looking around and I see how you get a lot more bang for your buck by getting lead acid instead of lithium. The lithium power stations barely make the minimum for a single night.

I'm not sure how comfortable I am with an exposed battery (or two), wires and my ability to cobble together a reliable, convenient, attractive, charging/using solution.

I think I might have found a good compromise between the larger capacity of an exposed battery and convenience of a factory made powerbox.

https://www.canadiantire.ca/en/pdp/moto ... 2014p.html

• $180 CAD (~ $135 US)
• 28 Ah, 1600A, Sealed Lead Acid 1600
• 25 pounds - Not for quite portable, but luggable
• Battery leads can be attached to an external battery for extended life

So assuming my Airsense 10 (DC-DC adapter, 12 CM, passover humidity, no heated hose) draws 1.06 amps, this powerbox would provide ~ 26 hours of use or slightly better than 3 eight hour nights.

[DavidY]

I bought my Resmed DC DC convertor from Sleep Yeti in Alberta. It was under $100. Shipping was not free (free if order over $700), but was around $7 or so.

I am considering the Goal Zero Yeti 400 (non Lithium model)....it was under $500 around the holidays. Regular price is $600.

Dave

[HoseCrusher]

Here is a test I ran on a Lithium Ion jump start pack (NOCO Genius GB150).

viewtopic.php?f=1&t=171369

Highly recommended as a jump pack and can also serve as a power supply for a nights worth of CPAP.

[palerider]

Thanks for that.

Did some looking around and I see how you get a lot more bang for your buck by getting lead acid instead of lithium. The lithium power stations barely make the minimum for a single night.

I'm not sure how comfortable I am with an exposed battery (or two), wires and my ability to cobble together a reliable, convenient, attractive, charging/using solution.

You tuck the wires in a battery box, I'm pretty sure that capnloki has that covered in his thread, but it's more of a footnote, instead of the 'main event'.

You end up with a box that has power going in, and power going out, or a 12v power connector to the 12v adapter for your cpap.

I think I might have found a good compromise between the larger capacity of an exposed battery and convenience of a factory made powerbox.

https://www.canadiantire.ca/en/pdp/moto ... 2014p.html

• $180 CAD (~ $135 US)
• 28 Ah, 1600A, Sealed Lead Acid 1600
• 25 pounds - Not for quite portable, but luggable
• Battery leads can be attached to an external battery for extended life

So assuming my Airsense 10 (DC-DC adapter, 12 CM, passover humidity, no heated hose) draws 1.06 amps, this powerbox would provide ~ 26 hours of use or slightly better than 3 eight hour nights.

It's pretty expensive for what you're getting.. I think you could DIY better

We're here to help advise.

[Hamguy515]

Here are a few factors to keep in mind when selecting or evaluating batteries for any use... this is a huge topic in and of itself, but one that it good to understand.

Not all "lead-acid" batteries are created equal, in spite of what the amp-hour rating on the label may lead you to believe. Starting batteries (like in your car/truck) are designed to deliver extremely high current for a very short period, but will degrade quickly if discharged more than around 30% of their capacity (some resources indicate you can go as low as 50% depth-of-discharge safely, but my mileage in this category has been markedly different than that). Deep-cycle batteries are designed to deliver smaller current rates over a longer period while also capable of deeper depth-of-discharge. Modern gelled-electrolyte or AGM deep-cycle lead-acid batteries in particular can routinely handle a 50% depth-of-discharge with no significant reduction of battery lifespan (while some resources suggest as much as 80% is acceptable - see my above YMMV disclaimer). I never allow my AGM deep-cycle batteries to fall below 11.9V (approximately 60% DOD). All of these batteries

What this all means, though, is that a deep-cycle lead-acid battery that's rated at 100Ah will have a USEABLE capacity of roughly half that number without negatively impacting the lifespan of the battery. The battery will go there and do what you're demanding of it, but it won't last long or let you do that many times without reducing its capacity.

Lithium-chemistry batteries, however, are capable of routine 80% depth-of-discharge, with a reduction in lifespan at higher DOD levels. Compared to the example above, you'd only need a 65Ah-rated battery to deliver the same USEABLE capacity of the 100Ah AGM.

One other factor to consider is the number of charge/discharge cycles the battery is rated to handle. At a 50% DOD, a quality AGM deep-cycle lead-acid battery should be capable of handling 1000 charge/discharge cycles while a comparable quality Lithium Iron Phosphate (LiFePO4) battery is typically rated for 2000+ cycles at an 80% DOD.

When crunching the numbers, you'll typically find that for this sort of application (deep discharge, low current draw), lithium-chemistry batteries will have a higher initial acquisition cost, but a LOWER total cost when compared to comparable lead-acid batteries (with comparable usable capacity) over the same period.

[JJR]

On another forum I just read about someone who woke up gasping for air due to a power outage, and that made me mildly concerned since with my face mask, it would not be a good thing to suddenly lose electricity.

Why not just use a UPS system, like for a computer? It only has to run long enough for you to wake up, or till the power comes back on.

[ChicagoGranny]

Why not just use a UPS system, like for a computer? It only has to run long enough for you to wake up, or till the power comes back on.

What if the power is out for 48 hours?

that made me mildly concerned since with my face mask, it would not be a good thing to suddenly lose electricity.

All FFMs have vents that allow the user to continue breathing when the machine stops pumping air. Of course, if you continue sleeping, you might have apneas. Easy solution that is carried at many hardware stores - https://www.truevalue.com/power-failure ... K8QAvD_BwE

[Dog Slobber]

On another forum I just read about someone who woke up gasping for air due to a power outage, and that made me mildly concerned since with my face mask, it would not be a good thing to suddenly lose electricity.

Why not just use a UPS system, like for a computer? It only has to run long enough for you to wake up, or till the power comes back on.

Because UPSs are one of the worst values for capacity vs cost.

They typically don't have 12 volt DC output, so you're stuck with the inefficient AC inverter. Many have a beeping alarm that can't be disabled.

From the information I've learned here, I'd classify the the following broad category of battery backups, with regard to battery life vs cost.

1. Do it yourself (Lead Acid)
2. Consumer Power Station (Lead Acid)
3. Consumer Power Station (Lithium)
4. UPS

[babydinosnoreless]

On another forum I just read about someone who woke up gasping for air due to a power outage, and that made me mildly concerned since with my face mask, it would not be a good thing to suddenly lose electricity.

Why not just use a UPS system, like for a computer? It only has to run long enough for you to wake up, or till the power comes back on.

A UPS is what my husband set up for me. We are in the greater Phoenix area with (knock on wood) no long power outages only shorter ones due to summer moonsoon storms.

[jamesbond007]

I bought a brand called "Poweradd" from Amazon last fall for my 7-day camping/bike ride. It served me very well. 100% charge on the battery lasts me 2 nights of sleep (8 hrs each night) with climate controls and humidifier turned off on the Resmed Airsense Autoset 10. It also took about 6 hrs to charge from 0 to 100. Very happy with the purchase. It seems like holding the charge well too. I charged it to 55% and stored it in my nightstand in October and it still shows 53% available. It is a Lithium Polymer if it matters. Of course, I had to buy a separate power adapter and DC converter for my ResMed.

[CapnLoki]

On another forum I just read about someone who woke up gasping for air due to a power outage, and that made me mildly concerned since with my face mask, it would not be a good thing to suddenly lose electricity.

Why not just use a UPS system, like for a computer? It only has to run long enough for you to wake up, or till the power comes back on.

The typical UPS you get at the computer store for under $100 has within it a 7 Amp-hour battery. These are the same as the scooter batteries I recommend, but 20% of the capacity. In addition, the UPS generally doesn't have a 12V output, so you're always running through an inverter, meaning that this is equivalent to only 4 amp-hours. If the issue you're concerned with is short outages, under an hour, this may be the easiest solution. If you have longer outages a basic UPS won't cut it. Larger UPS's with large batteries are available, but the price goes way up and you can do better with a DIY setup.

BTW, while some folks wake up quickly during an outage, others have reported sleeping for hours - I've gone for about 30 minutes without waking. You won't actually suffocate.

[JJR]

A car hit a pole and knocked out our electricity in the middle of the night last night. I never noticed until I got up to pee and noticed the lights didn't work. So... having my CPAP fail is a non-event. Except for stopping the sleep apnea, that is.

[higgledy]

Using a computer UPS is the easiest solution for short term outages. Then if the power-out lasts longer you can always purchase a better solution in the morning. Unless the power-out event is the apocalypse. In that case you will be SOL.

Several years ago I bought a marine battery for camping and what not. It works great but what a PIA it is to carry, it is very heavy. Plus, I don't like traveling with such a heavy item loose in my car's trunk. In an accident that thing could come forward into the cabin and kill someone. Or it could get crushed, leaking acid, starting a fire, exploding, etc.
Also, recharging lead acid batteries releases hydrogen, which is not a safe gas to accumulate in your house. (think Hindenburg) Yes, I am a worry wart. But don't hate me for it.