another UPS/battery backup post

[Bearded_One]

What brand is your CPAP? Many CPAP blowers work directly from 12 volts; they use a power brick to convert house power to 12 volts. When the power is out or browned out, the UPS uses an inverter to convert the power from an internal battery to house current. If your CPAP runs from 12 volts, it is a waste to convert the 12 volts to house current and then convert it back to 12 volts.

The Battery Geek CPAP batteries are very nice, but they are quite expensive. Some people have found gelled electrolyte battery packs that are considerably less expensive, although they are heavier and less portable. You should get at least a 12 amp hour battery, it will last one night (CPAP blower only).

[stacia123]

My CPAP is a Remstar Pro M with C-Flex and an integrated humidifier.

I want a UPS for brownouts because they occur a lot, because the brownouts usually don't last a long time, and so an alarm goes off alerting me to an issue with the power. Since I wake up with the machine off or working at low power and have very bad days because of it, this is something I feel I need to do ASAP.

A battery is something I will get to in time, but have to wait on it. It's not as urgent, there's not enough money, and there's not enough room/ventilation for a deep cell battery. We'd have to do a lot of work to get something rigged up. Thankfully full on power outages are rare for us, as we're just a half block away from the city works depot, so power is restored here quickly. A battery can wait.

For when I do eventually get a full battery, it appears I would need a battery (like this one http://www.defender.com/product.jsp?pat ... 8&id=87576) as well as a cigarette lighter cord (cpap.com has them for $25) and a lighter-to-battery cord, not sure how much that would cost. I have no idea if I'd need an inverter, but I doubt it. I'd also need a multimeter (about $20) and a battery charger (about $80). All told, we're looking at $350 or so, $330 if I forgo the multimeter.

Meanwhile, the lithium ion battery is listed as $399 retail on the batterygeek website. I think I'd spend the extra $49 for the convenience, especially since I hope to travel a bit.

[st3v3k4hn]

Can I verify something? A UPS is essentially a battery + an inverter. The UPS mentioned earlier in this thread (Xantrex XPower PowerSource 400) is essentially a 40 Amp hour battery, set up to charge from AC power and to convert the DC battery power back to AC. You can buy this item for around $140, which is far cheaper than most deep cycle batteries, and at 36 or so lbs its actually lighter than most batteries too (although the batteries would have more juice). Still, you could leave your cpap plugged in all the time and it could provide power during any blackout, and I don't see any reason you couldn't take this camping or on the road and just use it as a battery. Yes the inverter will be less efficient than running directly from an AC battery, but 40 amp hours should be enough for, well, lets say 30 hours, thats almost 4 nights which is plenty for me. So, if you buy the UPS for a brownout situation, couldn't you just use it like a battery - only diff is you're running on AC vs DC. Is that right?
Steve

[Kerwin]

Why bother?

Get a power inverter for your car big enough to run the PC.

You may want to keep the UPS in there for the disconnect when you start the engine.

You could just wire the inverter directly off the battery, but:

1) You are going to drain your battery over time.
2) The voltage drops significantly when you start the engine. The inverter will increase the current it draws to meet whatever power demand is on it. If you have significant power draw when you crank the engine you are could over-current the wiring, the fuse or the connectors of the inverter.

[st3v3k4hn]

Why bother? Get a power inverter for your car big enough to run the PC. You may want to keep the UPS in there for the disconnect when you start the engine.
You could just wire the inverter directly off the battery, but:
1) You are going to drain your battery over time.
2) The voltage drops significantly when you start the engine. The inverter will increase the current it draws to meet whatever power demand is on it. If you have significant power draw when you crank the engine you are could over-current the wiring, the fuse or the connectors of the inverter.

I don't think we understand each other - I am talking about running my CPAP from the UPS all the time, at home, to allow for sleeping thru a power outage. I would also occasionally take it (car) camping, but thats not the main point here. My Respironics M series auto does have a DC input, so I could run from a battery, but this seems less kludgy. Plus this way I could also run my heated cpap Sleepzone tube from the UPS. Assuming 80% efficiency, I could probably run the cpap & heated tube for 2+ nights on the Xantrex Powersource 400 without a recharge.
By the way, I've been looking around and it looks like Duracell sells an equivalent UPS (same name and specs) which can be had for quite a bit less (like $90 vs the $130 or so for the Xantrex). I think I am going to order one soon...
Steve

[Insulation Tim]

I realize that this is an old post, but how did that work for you...the UPS?

This is the way I power my office phone switch, but would it have the "juice" to run a CPAP all night long if the power were to die?

[WilsonVilleUSA]

Here is what I did...


viewtopic/t36354/viewtopic.php?f=1&t=23 ... 49#p206949


Works great, no problems, no alarms.