Power outage

[matthewb]

Thank you for the information about your UPS. matthewB. I wasn't aware that such large and adaptable UPS units were available. I'm curious as to what make and model it is, and how much it cost. (No links, of course). It sounds like a unit one might find in a medium size office, rather than a home office.

Mine is indeed an "office" ups, CyberPower OLS3000E 3000VA/2400W On-Line Tower UPS  This unit has replaced my 1500 W unit now (no longer available, as its about 4 years old). about $800 plus additional batteries (price may vary by location)

My unit is fitted with additional external batteries and supplies the pc equipment and the dedicated outlet i have in the bedroom for the Bipap and clock. It comes with 9AH batteries as standard and gives about 15 mins run time at 1200W but you can fit additional external packs as I have done.

Another option is the Eaton 3000W rack mount UPS, that one is locally made and will run anything, just add batteries to your desired capacity requirements.

Any UPs sytem to run stuff for a long period is going to need batteries with suitable reserve capacity. This is the expensive bit. The UPS unit price also indicates to a certain extent the quality of the unit in regards to battery maint. Mine offers 5 stage charge and does auto load cycling and tests weekly. Cheaper models do not. Mine also runs "stand alone" so if theres no mains and its shut down, I can manually switch it on and have power.

Home user models are fine, as long as you accept that if theres a power failure, the beeper will indeed wake you before you run out of air support. If this is something you want, or can use to your advantage, then this might be all you need. Personally, living where I do, and the issues we have with supply here, I elected to go with something a bit more substantial. During winter, outages of 3-5 days are not uncommon. I can always fire up the standby generator to keep everything going if i need to, but at 3 am with snow on the ground, i'll let the ups take me thru until the morning.

[matthewb]

Thanks to all who've posted so far. Enjoying reading this. All good info for the learning experience about UPS, general and specific backup possibilities, etc.

Drop me a line if you have any specific questions Dave, I deal with this stuff (along with outer rubbish) at work

[SarcasticDave94]

Thanks to all who've posted so far. Enjoying reading this. All good info for the learning experience about UPS, general and specific backup possibilities, etc.

Drop me a line if you have any specific questions Dave, I deal with this stuff (along with outer rubbish) at work

Thanks, I'll take note of the offer. Need to defer till a bit later for dollar reasons. But am really interested to get backup in some form when able.

[SuperSleeper]

I would think that there would be some way to get by cheaper...

For instance, wouldn't it be possible to hack up an existing UPS (like the standard consumer-grade (home-use) ones that cost about $80) so that you remove the small internal battery and hook it up to an external marine deep cycle (lead-acid) battery that is rated around 100 amp-hours? 

Those batteries are around $100, plus the UPS at $80 or so, and you're at less than $200 for a system that would run your CPAP for at least 2-3 nights without taking the lead-acid battery too low.  (all you'd have to do is snip the wires to the small beeper on the UPS to prevent it from waking you up).

I wouldn't think that the amp-hour rating of the larger battery would make a huge difference as far as how the UPS operates, but I'm not sure.

Thoughts on doing something like that?

[foxfire]

I would think that there would be some way to get by cheaper...

For instance, wouldn't it be possible to hack up an existing UPS (like the standard consumer-grade (home-use) ones that cost about $80) so that you remove the small internal battery and hook it up to an external marine deep cycle (lead-acid) battery that is rated around 100 amp-hours? 

Those batteries are around $100, plus the UPS at $80 or so, and you're at less than $200 for a system that would run your CPAP for at least 2-3 nights without taking the lead-acid battery too low.  (all you'd have to do is snip the wires to the small beeper on the UPS to prevent it from waking you up).

I wouldn't think that the amp-hour rating of the larger battery would make a huge difference as far as how the UPS operates, but I'm not sure.

Thoughts on doing something like that?

That's what I did. There are several websites with instructions on how. I bought a used APC BackUPS unit on ebay for $30 and connected it to a 70Ah battery. There are some tradeoffs. First it will take a very long time to charge a big battery with the tiny charging circuit in the UPS, think days instead of hours depending on the battery you use. Second, never attach the full rated load to a UPS with a big battery because it probably is not designed to run for hours at that load, only 10-15 minutes. The UPS I bought is rated for 550VA, but my CPAP only draws about 60W so it should be fining running a few hours at that level.

[foxfire]

I would think that there would be some way to get by cheaper...

For instance, wouldn't it be possible to hack up an existing UPS (like the standard consumer-grade (home-use) ones that cost about $80) so that you remove the small internal battery and hook it up to an external marine deep cycle (lead-acid) battery that is rated around 100 amp-hours? 

Those batteries are around $100, plus the UPS at $80 or so, and you're at less than $200 for a system that would run your CPAP for at least 2-3 nights without taking the lead-acid battery too low.  (all you'd have to do is snip the wires to the small beeper on the UPS to prevent it from waking you up).

I wouldn't think that the amp-hour rating of the larger battery would make a huge difference as far as how the UPS operates, but I'm not sure.

Thoughts on doing something like that?

That's what I did. There are several websites with instructions on how. I bought a used APC BackUPS unit on ebay for $30 and connected it to a 70Ah battery. There are some tradeoffs. First it will take a very long time to charge a big battery with the tiny charging circuit in the UPS, think days instead of hours depending on the battery you use. Second, never attach the full rated load to a UPS with a big battery because it probably is not designed to run for hours at that load, only 10-15 minutes. The UPS I bought is rated for 550VA, but my CPAP only draws about 60W so it should be fining running a few hours at that level.

[OMyMyOHellYes]

I suppose you could, but that would put you back into the inverter territory....

[matthewb]

Biggest issue is the "home user" units don't have a decent charger able to handle bigger batteries, and in fact, most will drastically shorten the life of a lead acid battery as they charge in a totally different fashion. SLA, Glass Mat and lead acid are all different and require different charging systems, and at the correct rate for the battery. While going from a 9 AH SLAto a 20AH SLA isn't too bad, going from a charger designed at a c/20 charge rate on a 9AH SLA to a 100 AH Lead Acid deep cycle battery would mean the charger would barely keep up with the self discharge rate on a 100 AH battery thats at 70% capacity.

[PoolQ]

I built this system and it works great. No need to open up consumer products and move wires around. This is a lego solution, snap,snap,snap done. No clicking, buzzing, or beeps. You will never know that your CPAP switched to battery and back.

[SimonHolzman]

Your design sounds wonderful !

My wife and I both use CPAPs (no humidifiers but different brands though presumably both some variety of 12v).

We live in the boonies and get the occasional power glitches which can last from seconds to hours. Neither of us likes waking in the middle of the night to fiddle with stuff so the automatic switchover seems ideal for us (and the lack of an alarm).

If we lost the power for more than one night, we would adjourn to a motel or a friend's place so we really only need 8 hours of power... BUT, how would we tweak your design to work for two CPAPs instead of just one, assuming the battery can handle 2x8hrs ? Would we just have both CPAPs connected to the output of the PowerGate or would that just provide 6v to each of them ?

Thanks,

Simon.