anyone ever try a computer back up? you can get one for about $50 that at 400w should keep a resmed a10 running for over 4 hours
03-14-2015, 07:06 AM
(This post was last modified: 03-14-2015, 07:29 AM by OMyMyOHellYes.)
Generally not well suited for long term power. Very inefficient. Designed to allow graceful shutdown of a computer system in a short term window, not extend run of an appliance.
UPS = battery + charger + inverter + switching/control mechanism + power input hardware + power output hardware.
A 450 W CyberPower (AVRG750U) spec sheet shows it has an expected run time of only two and a half minutes at 450 watt load, seven minutes at 225 watts. That unit has a 7AH 12 V battery. Assuming a 30% loss to the inverter and switch (I am guessing and probably being optimistic) - best case scenario, you are talking maybe 5AH available battery capacity.
Using Resmed's Battery Guide, and assuming that the A10 setup includes climate line tubing, humidifier set to auto, and an average pressure of 10 cm, an 8 hour run, with safety reserve, would require a 46 AH 12 V battery. Without allowing any safety margin (assuming a perfect battery under perfect conditions) it would require a 30AH super battery (Resmed shows current draw at that pressure is 3.77 amps). Maximum theoretical run time under those perfect conditions would be maybe an hour and 20 minutes. And since we live in the real world and there is no such thing as a perfect condition super battery, I would assume less than an hour.
Which, if the power blinks for only a couple of minutes, the UPS would be good. I run a UPS on my broadband provider's wireless home gateway router because we have mini-outages lasting a minute or two maybe once a month or two. When those happen, every router in this part of town goes down. When power comes back up and all those routers try to initialize and log back on the network all at the same time, it takes a long time to get back online. That is just a convenience thing for me, not a medical necessity.
But if the outage lasts more than an hour, the UPS is probably not gonna make it through running an A-10 CPAP.
If the power goes out, I wake up right away. If the outage lasts more than a couple of minutes, I just get up, bring in a battery, hook it up, turn off the humidifier heat, and go back to sleep. The little 35 AH batteries will drive my PR 560 for more than a week in the non-heated condition. Heated humidifiers and tubes eat a LOT of electricity.
And speaking of A-10s, I wish I had one. Not the Resmed variety, the Fairchild Republic version.
03-14-2015, 07:31 AM
(This post was last modified: 03-14-2015, 09:51 AM by justMongo.)
OMM is spot on. The computer UPS is only good for getting you through transient power loss.
Plus, many UPS use a stepped approximation to a sine as their output on battery. The discontinuities do not work well with newer computer power supplies with active power factor correction -- nor do they work well with a CPAP's power brick.
An option I like is the Optima yellow top, spiral cell, AGM deep-cycle battery.
You keep it on a float charge using a Deltran Battery tender. You will have to get up and connect the CPAP to the battery -- you'll need resmed's 12V to 24V inverter for their machines.
OMM: I do love that A10 Warthog. it's 30 mm GAU-8/A Avenger Gatling-type cannon can put a lot of hot lead on target. Or, depleted Uranium anti armor sabot rounds.
INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.