DiverCTHunter wrote:rmh996usa wrote:
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 dcacdc 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.