Battery back-up to get thru the night (or two nights) in the event of power outage.
-Reasonable cost (<$150)
-Automatic- no waking up to alarms, switching things around, starting generators.
-Power not one, but two APAPs, and the humidifiers as well.
Options I looked at and rejected:
-CPAP.com battery pack. I have one and it is great for a night on the road, but doesn't power humidifier. Not a long term solution/inconvenient (oops! forgot to charge it)
-Computer type UPS. Will power humidifier since it has inverter, but not enough life to last more than an hour or so.
-Generator. Have a small one, but don't want to hassle with fuel, noise, hooking it up in the middle of the night, etc.
Nothing on the market (that I am aware of) that meets the requirements or accomplishes the goal. So I decided to cobble together my own custom back-up unit.
There are several warnings in the forum about the need for "Pure Sine Wave" inverters needed to power CPAPS and their HH units. My wife and I both use Remstar M series Pro APAP w/heated humidifier. The APAPs run on 12v dc, conversion done in the power supply. The HH uses AC.
I contacted Respironics asking about the requirements and they told me the M series HH would be fine on a "standard" inverter (ie "Modified Sine wave) but to make sure it was rated for a minimum of 300 watts.
That hurdle cleared, I began to gather parts. They are:
-Battery- $65 from local battery house. General purpose sealed lead acid lawn tractor type, 35 AH rating.
-Inverter- Xantrex 400 w/digital display. I already had this, If I recall correctly it cost about $35 at Costco.
-Automatic charger- Schumacher 1.5amp charger. $18.44 at Wal-Mart.
-Misc wire/terminals- $4.00 at the battery house.
-Attractive case- $4.97 six-pack cooler from Wal-Mart
Total- A touch under $119 with tax.
Hooked it up and viola! Battery backup that can have the units plugged in and be always "on-line". Units run off the inverter and battery, battery consatantly being charged. If power goes out, don't even have to get up and do anything.
We slept on it for two nights (without battery charger plugged in) with HH's in passive (no heat) and it worked great. The machines were kept plugged in even when we weren't sleeping, so there was always a draw going.
I haven't yet tested it's full capacity, will do that later this month to see how many nights can get on a charge. I expect it will do 2 machines for 3 nights on the inverter with passive humidifier use.
For longer term use, I also wired a 12v receptacle to it, so machines can be powered off the DC cord and get even more life by not using humidifier and bypassing the losses from the inverter. I also plan to test capacity in this configuration. My rough numbers tells me to expect about 8-9 nights for a single machine.
It is a fairly small package, the cooler encloses the battery and all the wires. Charger is left out for air flow and cooling, inverter sits on top and is held in place with bungee cord hat came on the cooler. I am pretty happy with the way it turned out and no longer fear waking up to the sensation of suffocation.