battery power?

Amp Hours vary by how much current you draw.

Specifications

•Minutes at 15 amps:348 87 Ah
•Minutes at 25 amps:210 87 Ah
•Minutes at 5 amps:1265 105 Ah
•Minutes at 50 amps:87.4 72 Ah
•Minutes at 75 amps:53 66 Ah
•Minutes at 8 amps:706 94 Ah

At 4.1 Amps, use the 5 Amp number
you'll get 105/4.1 = 25 hours.

At 6.5 Amps, use the 8 Amp number
you'll get 94/6.5 = 14 hours.

In theory, that is. Actual results may vary quite a bit.

What indication do you have as to the state of the charge that the battery has left, during use? Let's say that you are drawing current on the base of 8 hours, total use time, and you have used the machine for 5 hours, at which time the power company announces that the power will be restored in 3 hours. So you want to know the charge left in the battery. As I understand it, you want to know the present battery voltage. Has John Fisher's design a provision for it?

avi123 wrote:What indication do you have as to the state of the charge that the battery has left, during use? Let's say that you are drawing current on the base of 8 hours, total use time, and you have used the machine for 5 hours, at which time the power company announces that the power will be restored in 3 hours. So you want to know the charge left in the battery. As I understand it, you want to know the present battery voltage. Has John Fisher's design a provision for it?

There's really no good way to know. It's very difficult to accurately determine the amount of charge left in a lead acid battery unless you get one of those things where you suck some acid out of the battery and read the charge level off the float. That's a pain and doesn't work on sealed batteries.

You can tell fairly well when it's full or "empty" if the battery is in good shape. If you measure the voltage and look it up in a table, you might calculate it's 50% full, but it might really be 30% or 70%.

There's a voltage vs. remaining charge chart here. but it's not really that accurate. http://www.windsun.com/Batteries/Battery_FAQ.htm There's a lot of good info on that site. I believe the accuracy of that chart goes down as the battery gets old or otherwise "unhealthy." I also think some types of lead acid batteries have slightly different voltage curves.

Your best bet is to figure out the approximate charge time you get on a full charge and keep track of the hours.

Many jumper batteries may have a built in charge indicator. Once again, they're fairly good at telling you dead or alive, but percentages in the middle are very iffy, especially as they age.

By the way, even if you have a deep cycle battery, you shouldn't just run it until your CPAP quits. Even a deep cycle battery suffers if you discharge it below 11V or so, and the voltage drops really rapidly after that anyway. One of the advantages of the ResMed converter is it shuts off before you over discharge the battery.

The "standard" way to check a lead acid car battery is with something like this:

http://www.amazon.com/Schumacher-BT-100 ... B000AMBOI0

You have to figure out how to use it, though. You hook it up and read a voltage, but it doesn't give you a good reading until you push the switch. At that point, it puts a heavy load on the battery and you read the voltage. You only hold the switch down for a second or so because it will overheat.

The tester gets really hot and has to be connected right to the battery.

Unfortunately, it's intended for car starting batteries, not deep cycle batteries. It's still useful, but you have to figure out what the readings are for your battery.

It's a bit intimidating and inconvenient.

There are some more expensive smarter testers.

I was looking for some fairly cheap charge indicators that would at least give you some indication, but I didn't find anything that seemed reasonably priced. Your best bet would be an inexpensive voltmeter and a chart.

I keep reading that hospitals check their Lead-Acid batteries every 6 months.

The following is an excerpt from a Dec. 2005 report ( I am still looking for the slides which go with its presentation. )
I assume that those Lead-Acid batteries have improved a lot since then.



http://www.fda.gov/MedicalDevices/Safet ... 127813.htm



We’re going to step away from the infusion pump work that we’ve done and go to an older study, where we looked at batteries for a pre-hospital defibrillation program that we have here in Ottawa. We looked at batteries from a supplier, and they were brand new, they were 14 months past their date of manufacture, so they’re a little dated, and I would suggest that that’s not too uncommon if you are purchasing your batteries locally. So we looked at the batteries and we found that they were presented to us, some of them had some very low capacities, and for the defibrillation program we again established a correlation and ... count, where our incoming inspection pass/fail criteria was 65%, and this graph, on slide 20, shows you that 46 of 126 batteries failed to meet our incoming inspection criteria.

I talked with the battery distributor, as well as the battery manufacturer, and the distributor did not want to take the batteries back initially, and wanted us to work with the battery manufacturer and find out if our testing protocol was legitimate. They verified all of our test procedures and they said that the batteries, again, sealed lead acid batteries, probably had reduced capacity due to a lead sulfation effect and that since they were only 14 months past the date of manufacture, that if we employed an over-discharge protocol we would probably be able to remove the lead sulfate from the plate, allowing that portion of the plate to now accept a charge and hold a charge. So they illustrated what the protocol had to be for over-discharging a sealed lead acid battery, and as radical as it may seem, what the protocol did was brought the terminal voltage down to approximately 50-100 millivolts, so you’re taking a 12-volt battery, you’re placing it over a power resistor and allowing it to sit overnight. So you fully discharge the battery, fully removing all lead sulfate from the plate, converting the chemistry inside the battery, and the next morning you come in and you remove the battery from the power resistor, allow time for the battery to settle, and you recharge it for 24 hours, you place the battery back on the analyzer and see how it did.

Well, now it was quite astounding that all of the batteries with very low capacity bounced straight up to where the manufacturer of the batteries thought they would come out, based on our testing criteria. So what we came up with was a new method of treating poorly conditioned batteries. The point is, if you do not look at batteries when they come into your door, whether they are brand new, whether you got them from Distributor A or Distributor B, if you do not look at them you do not know what their ability is to perform. Here, we saw that 46 of the batteries would not have performed well in our pre-hospital defibrillation program. After the over-discharge protocol, all 126 batteries came well above the 70% level that you see on that graph. The real message is: do not assume that just because you’re purchasing a new battery, whether you got it at a high price or a low price, that battery has to be able to perform, and the only measure of performance is by analyzing the battery’s capacity.

So to support what Tim was saying, what benefit does this provide us? Well, it gives us confidence in a battery’s ability to perform. It gives us predictability of the battery and the end product. We can now safely determine when is the end of life for this battery, and we have measures in our protocol of pass/fail criteria, and we certainly now use that as the standard as opposed to a date stamp. So do we keep our batteries longer than one year? Yes, we do. However, if the battery is unable to perform, it might be removed at ten months of use or six months of use. We keep a battery in service as long as it can meet the needs of our user.

archangle wrote:... Your best bet is to figure out the approximate charge time you get on a full charge and keep track of the hours. ...

This is why I recommend (and personally also do this) that you run your machine on the battery backup system once every month or two. I do not recommend waiting every six months. Run the battery backup for a couple nights. Doing this when there is no disaster is a great way to be certain the battery is still functioning well. If it has problems, then you have the chance to react BEFORE a crisis arrives.

Sure there are more scientific methods to test the battery. They also cost a whole lot more money. Why? All I really need to know is that the battery backup system will last for 2 or 3 days. If it fails, then I need to be certain the battery SHOULD have lasted that long. Did I miscalculate the load? If not, then the battery may have reached the end of it's usable life.

And yes, the S9 voltage converter is a good option. However, I do NOT recommend running the humidifier when running battery power. That won't work for everyone. But most people can survive for a couple nights if they only use passive humidification. Turn off the humidifier and just have the water in it. That normally suffices. It's not perfect, but it keeps the size of the battery to a minimum.

And as to the battery backup system being over $600 ... Yikes! I simply would not accept that. My unit has lasted three nights without problem and I spent a LOT less than that. Assume I spent as much as $200 to have someone else construct it ... and that's way too high ... it would still be well below $600.

Obviously, others found similar solutions that help reduce the costs. I'll follow up on those and add them into the Wiki. There appear to be some good options listed there.

Pssible alternatives for S9 Autoset, to be placed on the ventilated porch:





Regular Price:
$949.95


Special Price: $799.00


FREE SHIPPING...The Honda EU1000i has a maximum of 1000 watts/8.3 amps @ 120V. It is super quiet, 53-59 dBA and weighs less than 29 lbs! It is fuel efficient with a run time of up to 8.3 hours on 0.6 gallons of fuel. It features Honda's inverter technology - stable power for computers and more. This generator is great for tailgating, RVing, and other recreational activities where light weight portable power is a must! * This Unit is now 50 state compliant exceeding California EPA C.A.R.B regulations

Or:

http://www.wayfair.com/Generac-800-Watt ... N1294.html

cost: $364

Is there a simple battery pack that will get me through the night? preferably something I could recharge. I have the Resmed s9. Thanks!

jps1012 wrote:Is there a simple battery pack that will get me through the night? preferably something I could recharge. I have the Resmed s9. Thanks!

There are several options. The first is a battery pack just for the S9:

https://www.cpap.com/productpage/resmed ... hines.html

The second would be a battery pack plus a 12vdc to 24vdc converter:

https://www.cpap.com/productpage/respir ... -pack.html
https://www.cpap.com/productpage/DC-Con ... hines.html

There are other options that will work, but these represent the simplest methods to get the job done.

This would probably get you through a single night for an S9 machine, without the humidifier running. It would also allow you to run other low power AC devices for short periods of time or start your car, so it's dual use.

You'd get more lifetime if you use the ResMed DC-DC adapater.

BTW, the Sears Diehard 1150 jumper/inverter/compressor is on sale for $100, regular $150 today. I just ordered one.

Apparently, online price only, but free shipping or local pickup at their store.

Following John's post, I think that for a backup battery for an S9 Autoset + Humidifier + Climate line,
you'll need only these two items, totaling $383.95:

https://www.cpap.com/productpage/respir ... nAodR3cAHg

https://www.cpap.com/productpage/DC-Con ... igodigital

(Less the alligators clamps)

avi123 wrote:Following John's post, I think that for a backup battery for an S9 Autoset + Humidifier + Climate line,
you'll need only these two items, totaling $383.95:

https://www.cpap.com/productpage/respir ... nAodR3cAHg

https://www.cpap.com/productpage/DC-Con ... igodigital

(Less the alligators clamps)

Should work fine for one night without heated humidification.

There are always tradeoffs.

You are paying considerably more than you would for similar capacity with the Diehard jumper battery.

Diehard

$150 (On sale for $100, don't know how long)
22 Ah
22 lbs
Can run without cost of ResMed converter through built in inverter at the cost of some capacity. I'll guess about the same run time as the Resp.

Add $85 for the ResMed converter and get the full 22 Ah capacity.

Jump start, AC power, air compressor function available as an added bonus.
Modified Sine Wave power on AC. Don't use for S8 or older Respironics humidifiers.


Respironics plus Converter
$384

14.4 Ah
14.5 lbs
Package better for airline travel. Better looking (?).

Both are sealed lead acid batteries with an external charger.

That diehard battery jumpstart unit looks nice. I just picked up a different unit at Costco today. $69 18AH, no AC outlets or usb like the diehard one. But I had bought it for car use. Didn't think about cpap usage.

Same as the one I bought at Costco:
http://www.amazon.com/PowerStation-PSX- ... B002YVU8WS

AVI, that Honda is a great machine, I would stay away from the chinese Generac ... However ... We decided to go to the EU2000i from Honda as we can also power our fridge ...