Home Back Up power / surge protection

[TinyL]

Went and purchased a lithium battery for when I am camping with the ResMed DC Converter and that sets me up as far as camping. But now I am looking for home battery usage. I was just going to go get a big deep cycle battery and keep it handy...but then I was wondering if one of these uninteruptable power supplys would be enough to get 8-9 hours of full service with the humidifier on. Was thinking this would be good bang for the buck since you get surge protection, battery back-up and don't have to wake up to change over. But I am not really sharp at figuring out this whole amp hours and what / how big a unit I would need to operate a S9 AutoSet running 9 H20 with humidifier on. I know APC and other companys make lots of different sizes but I don't know what would work. I can find lots of threads on camping batterys but nothing talking about the UPS units. Do they have enough oumph?

[JJJ]

Went and purchased a lithium battery for when I am camping with the ResMed DC Converter and that sets me up as far as camping. But now I am looking for home battery usage. I was just going to go get a big deep cycle battery and keep it handy...but then I was wondering if one of these uninteruptable power supplys would be enough to get 8-9 hours of full service with the humidifier on. Was thinking this would be good bang for the buck since you get surge protection, battery back-up and don't have to wake up to change over. But I am not really sharp at figuring out this whole amp hours and what / how big a unit I would need to operate a S9 AutoSet running 9 H20 with humidifier on. I know APC and other companys make lots of different sizes but I don't know what would work. I can find lots of threads on camping batterys but nothing talking about the UPS units. Do they have enough oumph?

Not enough amp hours unless you get a massive one designed for commercial server installations. And then you are talking more bucks than a big deep cycle battery.

[SuperSleeper]

Yep, most home/office UPS units have very small batteries as far as amp-hour rating (even the larger ones). You'd be lucky to power a CPAP with heated humidifier for much more than 30 minutes. As JJJ indicated, you'd have to spend hundreds of dollars to get a high-enough capacity UPS that would power a CPAP for an entire night, and in the end, it would probably weigh much greater than a simple marine deep cycle battery that you could have bought for $80.

It's all about the battery in the UPS. Check the amp-hour rating. To properly get at least one or more nights of CPAP use, you'll need a battery with a 100+ amp-hour rating. In addition, you'll have to make sure that the battery is made for numerous deep cycle discharges. Keep in mind that a "100 amp-hour rating" does not mean that it will power your CPAP for 100 hours, it's simply a rating for comparison purposes and your battery drain will depend upon how many amps your CPAP and humidifier is drawing at a specific voltage over time.

Most common household UPS units have sealed batteries that are rated below 12 amp-hours - which may power a CPAP for a few minutes at best.

Buy yourself an $80 12-volt lead acid Marine Deep Cycle from the local Wal-Mart, K-Mart etc. with a 100+ hour amp-hour rating and you'll be okay. And keep in mind that amp-hour rating is completely different from the CCA rating (cold cranking amps). If there is no amp-hour rating printed on the battery, it's not a deep cycle battery and it will not work for numerous deep cycle charging.

[TinyL]

Thanks! Big battery it is. Looked at Walmart on the way home last night and they had a size 29DC. Will stop buy and pick it up today, was worried I would need it last night with the severe storms that went thru. Living in Kansas means I will get a lot of battery days!

Edit: Wife just said the battery better fit in the cabinet too

Think I will mess with her tonight an place it in HER closet

[SuperSleeper]

You'll also need a good trickle charger to charge it, of course. One that charges at something less than 2-3 amps - the lower the charging amps, the better it will be on your battery, however it will take longer to charge with a trickle charger. I'd recommend a trickle charger over a fast charging system - it will extend the life of the battery. You can get chargers that will do both - fast charging and trickle charging.

Also, since these are lead-acid batteries, the top cap pops off so you can check water levels. The more you charge/discharge the battery, the more the water will evaporate in the cells. You'll need to top off the water levels with distilled water from time to time. Depending upon how often you charge the battery, of course - but I check my water levels once every other month or so. Make sure the water level never gets below the metal fins in the cells - that will ruin your battery.

[TinyL]

for all the info!

Found a Battery Tender at Wally World that charges at 1.5 amps so that should do the trick. Picked up the 29C Battery as well as a plastic battery box for it.

Just found this info while rumaging around at the ResMed site. Probably allready here somewhere but what the heck...here it is again.

Linky to ResMed Battery Info and Recommends

[SuperSleeper]

Just as a reminder, remember that although you can discharge your Marine deep cycle battery down to a very low level, for best performance (battery life), it's recommended that you don't let the battery get much below a 80% charge (12.4 volt charge). The less you discharge your lead-acid battery, the longer it will last. So, it's always best to re-charge the battery after a night's use rather than use it multiple nights before charging (if you can).

You can test the battery voltage with a cheap $10 volt meter, just make sure it's on the 12 volt setting. To get the true reading of voltage (open terminal), you'll need to let the battery sit idle for at least 4-5 hours with nothing attached to it - otherwise you'll get a false reading. I know it's not helpful now that you've purchased your battery already, but when I buy a battery (even for my car), I always take a long a small pocket volt meter to test the open terminal voltage, and if there's a choice, I always choose the battery that has the highest voltage reading. That way I'm making sure I'm not getting stuck with an older battery that's been sitting on the shelf for a year or more.

The chart below is for true deep cycle batteries (expensive). The "Marine" deep cycles you can get for around $80 at Wal-Mart are not "true" deep cycles, but rather hybrids that perform both a "starting" function and a "deep cycle" capability. So, the yellow and red zones in this chart aren't for the cheaper Marine batteries. In those, to be safe, I'd say the yellow range should be around 70% and the red would be around 60% charge. But for me personally, I never let my battery get below a 12.4 charge, ever.

[vsheline]

Also, do not have an inverter attached to the battery except when using the PAP machine. The inverter, even if the CPAP machine is not plugged into it, would draw some current from the battery all the time.

Good idea to have inverter rated for 150% or 200% of the expected max power needed by the CPAP machine & humidifier. If a 150W inverter is minimum size needed, I would use an inverter rated 225W or 300W, so the inverter would not wear out.

Take care,
--- Vaughn

[Sevensox]

Your getting a lot of good advice. We live in a rural area of Missouri and we do lose power from time to time. Last time for 9 days. I have a Honda EU2000i generator with aux gas tank. Add a long extension cord and that is how I got through those 9 days without power. We were full time RV'ers for 5 years so we needed the generator for places where there was no shore power.
Sometimes I did without the humidifier simply because it took more juice and we were in a place where we wanted to spend a couple weeks.
Good luck with you backup efforts.
Lee

[archangle]

The chart below is for true deep cycle batteries (expensive). The "Marine" deep cycles you can get for around $80 at Wal-Mart are not "true" deep cycles, but rather hybrids that perform both a "starting" function and a "deep cycle" capability.

There are sort of 3 types. 1) Starting 2) Hybrid starting/deep cycle or 3) deep cycle.

I've seen batteries labeled in all 3 categories at Walmart.

There's no clear cut dividing line between the types. You trade off high starting current vs. deep cycle by varying the design of the plates. You can continuously vary this trade off and there's no generally accepted hard and fast rule as to where you call one "deep cycle" and another "starting."

If you're going to leave it connected to the charger all the time, the right charger will make a big difference how long before you have to replace the battery. In theory, you want a "float" charger, which is one step "smarter" than a "trickle" charger. I've had good luck for many years with the Schumacher SE-1-12s charger hooked to batteries 24/7. There are probably others that work just as well, but I've got experience with this one.

In theory, you should disconnect the charger from the battery when you're connected to the CPAP. This is especially important if the charger has a "desulfator" function. Some chargers do some weird things with the battery voltage and pulses that may damage your CPAP. Note you have to disconnect the charger. Just unplugging if from power may not be enough if it has a desulfator.