Power outage - Backup did not work

[archangle]

When I lived on the east coast I worried a lot about power outages from rain/snow storms. Where I live in TX it's not that big of a deal. Does anyone know if insurance companies pay for cpap batteries? Maybe a doctor could write something about you needing it?

Almost everyone who's posted here about it has said their insurance won't pay for a backup power supply. The dogma seems to be that a few nights of no CPAP is not a life threatening issue, and isn't "medically necessary."

[ElvishKnight]

Almost everyone who's posted here about it has said their insurance won't pay for a backup power supply. The dogma seems to be that a few nights of no CPAP is not a life threatening issue, and isn't "medically necessary."

What!!! They just want us all to die?!?

[palerider]

What!!! They just want us all to die?!?

you're just an expense, of COURSE they want you to die.

[chriscowles]

Considering the potential for power failure in the middle of the night, and not wanting to bumble around in the dark, I'm exploring my options for setting up a backup system that my CPAP would run directly off, like a UPS. A recent power failure piqued my interest in this.

With that in mind, do other users here have standard wet cell batteries in their bedroom? If so, what consideration did you give to the potential for hydrogen gas posing a fire hazard? The cost of AGM batteries is not within reach.

Thanks

[HoseCrusher]

Hydrogen gas is usually formed during charging, not during use.

[chriscowles]

Hydrogen gas is usually formed during charging, not during use.

I understand that but I'd prefer to leave it plugged in continuously. That assumes appropriate charging equipment and checking fluid levels weekly (or whatever).

[HoseCrusher]

You can put the battery and charger in a separate ventilated room and just run a DC outlet to your machine.

[Goofproof]

Almost everyone who's posted here about it has said their insurance won't pay for a backup power supply. The dogma seems to be that a few nights of no CPAP is not a life threatening issue, and isn't "medically necessary."

What!!! They just want us all to die?!?

Check with your life ins company, maybe they will kick in, although they can probably claim suicide and void your claim. Jim

[archangle]

Unless you've got some megadeath super duper charger, you won't generate enough hydrogen into the room fast enough to matter. You'd also have to have some sort of charger fault that will be boiling away the water in the battery and ruining it in a few days anyway.

Note that hydrogen and oxygen does accumulate withing the battery case itself, whether it's a sealed lead acid or a wet cell. I'm discussing the risk of hydrogen coming out of the battery and making the air in the room hazardous.

If you have a charger fault this bad, an AGM or other SLA batteries will vent hydrogen as well. All of these types of batteries are VRLA (Valve Regulated Lead Acid) batteries and will vent hydrogen and oxygen if you create it fast enough.

Lead acid batteries generate hydrogen by breaking down water into oxygen and hydrogen. 18 ounces of water has 2 ounces of hydrogen and 16 ounces of oxygen. (Hydrogen has an atomic weight of 1, oxygen has 16, so H2O has 2 ounces of oxygen for 16 ounces of oxygen for 18 ounces of water.)

18 ounces of water is more than a pint. If you're "boiling" away more than 18 ounces of water in one day, your battery is going to be dead in really short order. Let's assume you're generating 2 ounces of hydrogen a day, though.

2 ounces of hydrogen isn't going to blow your house up, but it might make a pretty bang if you've got the battery in a sealed container. It would have to be a pretty well sealed container because hydrogen is a very small molecule and tends to dissipate pretty rapidly. Even if it's one of those battery box things, the lid doesn't fit that tightly and it also has vent holes.

Hydrogen/air mix is only flammable/explosive if it's above 4% of the concentration of the air in the room. Once it's out of the box, it's going to dilute itself around the room pretty quickly. Our 2 ounce number isn't going to be enough to make the whole room flammable. Also realize that the 2 ounces comes out over 24 hours, so it's got plenty of time to dissipate. Even energy efficient homes require one air change every 3 hours. You should be dissipating any hydrogen generated pretty quickly.

Realize that hydrogen is not toxic, although it could displace oxygen and suffocate you, or, of course, explode.

There's also another reason you can't generate hydrogen that quickly in a "normal" battery setup. It takes one electron to free one hydrogen atom from the water. Assume you have a 1 amp charging current.

1 amp current = 6.2E18 electrons per second
6.2E18 hydrogen atoms per second
1.037E-5 moles per second of hydrogen atoms
1.037E-6 grams per second of hydrogen atoms
.037 grams per hour
.89 grams per day per cell
The above calculations are per cell. A 12V battery has 6 cells multiply by 6
5.4 grams per day for one battery for 1 amp current.
0.18 ounce per day for one battery for 1 amp current

Now, assume a 10 amp charging current.
1.8 ounce H2 per day at a 10 amp current.
Consumes 16 ounces water per day.

In practice, the hydrogen will be much less than that because not all of the current goes into electrolyzing hydrogen. The batteries are designed to NOT generate hydrogen. This is the maximum theoretical hydrogen production. It's also only for a broken "runaway" charger.

[sleep_quest]

Considering the potential for power failure in the middle of the night, and not wanting to bumble around in the dark, I'm exploring my options for setting up a backup system that my CPAP would run directly off, like a UPS. A recent power failure piqued my interest in this.

With that in mind, do other users here have standard wet cell batteries in their bedroom? If so, what consideration did you give to the potential for hydrogen gas posing a fire hazard? The cost of AGM batteries is not within reach.

Thanks

I put together a pretty complete system since I live in earthquake country and I wanted it to be portable as well as reliable. Here is a link to my back up power set up discovery through design/build. It's a long thread but you might be able to glean something from it.

viewtopic.php?f=1&t=101194&p=949127#p949127

[chriscowles]

I put together a pretty complete system since I live in earthquake country and I wanted it to be portable as well as reliable. Here is a link to my back up power set up discovery through design/build. It's a long thread but you might be able to glean something from it.

Thanks for the reference. It's good to get different ideas from different people who have actually done it, and adapt them all to your personal situation.

[chriscowles]

Unless you've got some megadeath super duper charger, you won't generate enough hydrogen into the room fast enough to matter.

That's kinda what I was thinking. With a vented battery case and proper charging equipment/practice, the dilution factor mitigates the risk. I don't smoke and understand the importance of reducing the risk of arcs when working with the battery itself.

[palerider]

Unless you've got some megadeath super duper charger, you won't generate enough hydrogen into the room fast enough to matter.

That's kinda what I was thinking. With a vented battery case and proper charging equipment/practice, the dilution factor mitigates the risk. I don't smoke and understand the importance of reducing the risk of arcs when working with the battery itself.

it'll all be up by the ceiling anyway, and when it does go *BOOM* send the bill to arch.

[archangle]

Unless you've got some megadeath super duper charger, you won't generate enough hydrogen into the room fast enough to matter.

That's kinda what I was thinking. With a vented battery case and proper charging equipment/practice, the dilution factor mitigates the risk. I don't smoke and understand the importance of reducing the risk of arcs when working with the battery itself.

it'll all be up by the ceiling anyway, and when it does go *BOOM* send the bill to arch.

You know, you'd sort of think that, but gases don't seem to stratify that way once they have time to mix.

Oxygen has a molecular weight of 32. Nitrogen has a molecular weight of 28. CO2 has a molecular weight of 46. However, you don't end up with layers of CO2, nitrogen, and oxygen in the room. The O2 concentration is about the same at the ceiling as it is at the floor. Good thing, because with O2 being only 21% of the air, if it stratified, we'd suffocate if we got over 2 feet from the floor.

[palerider]

You know, you'd sort of think that, but gases don't seem to stratify that way once they have time to mix.

Oxygen has a molecular weight of 32. Nitrogen has a molecular weight of 28. CO2 has a molecular weight of 46. However, you don't end up with layers of CO2, nitrogen, and oxygen in the room. The O2 concentration is about the same at the ceiling as it is at the floor. Good thing, because with O2 being only 21% of the air, if it stratified, we'd suffocate if we got over 2 feet from the floor.

and yet, co2 pooling is one of the leading theories to explain SIDS, babies not stirring the air up enough to mix up the co2 they produce, and suffocating as a result.

so, your musing about co2 and oxygen and nitrogen includes saying that that hydrogen, at slightly over 2 molecular weight is going to hang around with that stuff that's what, 10, 15, 20 times heavier?

got something to back up your opinion?