Deep Cycle Home Backup Supply

[rmh996usa]

I am getting with my subject matter expert to develop a simple formula for DC applications that will get that type of information. If I remember right we need things like quality factors, temperature factors, effciency factors going ac to dc, dc to dc, etc. Over engineering to nuclear grade is my favorite game.

[DiverCTHunter]

I am still looking into the battery back-up schema. My goal is to feed power from the surge protection unit to a battery (via rectifier) and the S9 connected to the battery. A simple solution where if the offsite power trips, the S9 never knows that event happened because all that is dropped is the rectifier charging unit.

What are your thoughts on using a regulated DC power supply with a large-core transformer to isolate the DC side equipment?

My current setup:
Input: Tripp-Lite PR-7b voltage-regulated PSU (rated for 70w continuous draw, 97w peak draw at 13.9VDC)
Voltage converting Charge Controller: Mini-Box Open-UPS board with microcontroller regulated DC-DC buck/boost converters, over-volt and over-current protection. Output limited to 12.4VDC instantaneous
Battery: TBD

Right now I'm using a pre-drilled PCB from Radio Shack as a distribution block to feed my outputs and a ferrite-beaded pigtail at the end of the output. At some point I plan on resoldering the PCB to add a diode/filter-cap combo to the input side of the distribution block.

I'll probably toss a couple of Schottky's in as well so I can switch batteries and DC inputs without worrying about accidentally destroying the charge controller.

[archangle]

How long would this last with and S9 and humidifier? 14.8V 8.8AH LiCoxNiyMnzO2 lithium battery (130 Watt-hours)

I'm thinking if I bought one of these http://www.paulcbuff.com/vm120.php then I could get double duty from it.

Probably just wishful thinking....

The ResMed power guide is in my links in my signature.

With 9 Ah, my personal S9 usage and 100% efficiency, you'd get about 3 hours with humidifier, 9 without humidifier. Figure about half that given that some power will be wasted in the inverter, especially at low power levels.

Re: power surges.

Luckily, the ResMed and Respironics machines have external power bricks. Most of the time, the brick will be the only thing damaged, and they're relatively easy to replace. Of course, preventing damage in the first place with a surge protector is a great thing.

[locust78]

I like a lot of the designs and ideas presented in this thread, but was wondering if I could get away with using one of those car jumper boxes. I was looking for something compact, convenient, (and inexpensive) that would get me through one night only, without my humidifier. Do those jump boxes have what it takes? Could one of them damage my PRS1?

[khauser]

I have exactly that ... and it is ... OK. It's a 22Ah battery (http://www.sears.com/diehard-platinum-p ... 871988000P) ... pretty small for this purpose.

Pros:
- Quiet
- Always ready
- Last's a full night (IF you turn the humidifier off)
- Useful if your car battery dies (as mine did)
Cons:
- No Humidifier! (Or less than a night's sleep)
- Takes forEVER to charge (because it's a simple float charger with no boost, etc)

Here's the thing. It won't work for a 2 night power outage EVEN IF you find a place to charge it in-between because it takes more than 18 hours to re-charge.

I haven't tried it without the humidifier yet, so I don't know how long it would last. WITH the humidifer the battery voltage dropped too low after only 20% of capacity was used (according to its gauge), and that was 6 hours in to the night. This caused the machine to stop, reducing current draw so it would start again, etc. Not good for machine or patient.

I have decided to build a purpose-made UPS with a battery, intelligent charger/power supply, etc. I'm just now researching parts. Should be a very easy project. I'll run the machine using the 12V battery cord on a deep cycle battery with a power supply/charger that has a mode specifically for this. The idea is that the machine runs off the power supply whenever the mains are energized, and when a blackout occurs the power supply is off, but the battery is still connected, so power continues to flow to the machine. Not so much as a microsecond without power. More to the point, I don't have to get up!

[rmh996usa]

I am still looking into the battery back-up schema. My goal is to feed power from the surge protection unit to a battery (via rectifier) and the S9 connected to the battery. A simple solution where if the offsite power trips, the S9 never knows that event happened because all that is dropped is the rectifier charging unit.

What are your thoughts on using a regulated DC power supply with a large-core transformer to isolate the DC side equipment?

My current setup:
Input: Tripp-Lite PR-7b voltage-regulated PSU (rated for 70w continuous draw, 97w peak draw at 13.9VDC)
Voltage converting Charge Controller: Mini-Box Open-UPS board with microcontroller regulated DC-DC buck/boost converters, over-volt and over-current protection. Output limited to 12.4VDC instantaneous
Battery: TBD

Right now I'm using a pre-drilled PCB from Radio Shack as a distribution block to feed my outputs and a ferrite-beaded pigtail at the end of the output. At some point I plan on resoldering the PCB to add a diode/filter-cap combo to the input side of the distribution block.

I'll probably toss a couple of Schottky's in as well so I can switch batteries and DC inputs without worrying about accidentally destroying the charge controller.

While I believe what you are doing will serve well to keep the overall power draw as low as possible from the battery to the S9, ie allow the greatest max run time the S9H5 can run based on the available storage, I also think it is fair to get as close to that goal using normal retail equipment. This is to benefit the folks that do not have the background to create regulated supplies on their own.

My goal is to figure out each piece in the chain that will give reliable service with the best safety margin and be as cost effective as possible. To get something that is nuclear grade, the cost is prohibitive as each component from the case, the transformer, each capacitor, diode, etc would have to pass stringent reliability and stay within design parameters at all times in any reasonable environment. Thus, I am looking to determine what the specifications have to be and also the Cadillac version of what I want it to do.

For instance, the S9H5w/heated hose unit shall continuously run a minimum of eight (8) hours. But my Cadillac spec would be the unit will run continuously for a minimum of forty (40) hours as to support five, eight hour days.

(Based on the ResMed backup power paper that Archangel provided, my setup would take about a 75 amp-hours based on the ResMed equipment configuration of battery to inverter to normal ResMed S9 power supply to the S9. I want to eliminate the parasitic power draw of dcacdc if possible.)

Once we know the equipment with their power draw requirements, we can then figure the battery sizing. Then we get into lead/acid, lithium, etc. but, all of this needs to be balanced with cost as it will tough at best to get insurance companies to pay for it. I do think an argument can be made for the ResMed battery back-up for insurance. But, I want to go beyond that to create a reasonable and safe MacGyver’d equipment stack that anyone can build.

What is happening in this forum thread is building the identified pieces parts as to capacity, safety, reliability, etc, and this forum group will continue to ultimately come up with something better than I or any other single individual would ever come up with. Bottom line is no one is more interested in staying alive with CPAP equipment than this group. As such, we are responsible for our success, unlike the teachings of Hussein Obama where the government tax and spend is the answer.