Deep cycle marine battery backup questions. Please help.

[iSnore]

I'm starting to think the deep cycle marine battery might be the best option, with the converter cable from ResMed, and a battery tender.

I agree. I'd get an AGM version.

We lost power for 36-40 hours during Superstorm Sandy, and we had 24 hours without power during the last hurricane. I do not want to go without my ASV. I have sleep-onset centrals and I desat to the 70s and low 80s on the pulse ox. It freaks me the f**k out.

What are your EPAP (or Max EPAP) and Max Pressure Support settings?

Does your gathered data give you an idea of the average EPAP and Pressure Support?

What is your humidity setting if you don't use "Auto" with the ClimateLineAir tube? You may be able to compromise between that and no humidity with a low humidity setting and the standard SlimLine hose. See if you can get through the night with the humidity set on 3 or 4 with the SlimLine hose. It will help if you can place the machine lower than your mask, with the hose sloping down without too much of a dip in it. That way hose moisture can run back into the humidifier pan. That might be the best way to get through the first night while leaving capacity for another night or two without humidity, if necessary.

Edit to add more…

I've had good luck with the more affordable Chinese "Universal Battery" AGM brand. They're what Pride uses in their mobility scooters and wheelchairs, and are popular with a number of portable ham radio operators.

Using the example of a 100 AH rated model (# 12100). Using 80% of it could translate into 8 hours at 6 amps (some heat) plus 16 hours at 2 amps (no heat).

But that's assuming those amps are what your machine uses in those configurations.

Let me add even more. Absorbed Glass Mat batteries are NOT gel cells. They're two totally different technologies. AGMs can use standard flooded cell charging algorithms (and even more), while gel cells need a special softer algorithm to prevent hardening and cracking the gel. Some confuse these two technologies and use the less than optimal gel cell algorithm for AGMs.

[JVinNE]

I'm starting to think the deep cycle marine battery might be the best option, with the converter cable from ResMed, and a battery tender.

I agree.

We lost power for 36-40 hours during Superstorm Sandy, and we had 24 hours without power during the last hurricane. I do not want to go without my ASV. I have sleep-onset centrals and I desat to the 70s and low 80s on the pulse ox. It freaks me the f**k out.

What are your EPAP (or Max EPAP) and Max Pressure Support settings?

Does your gathered data give you an idea of the average EPAP and Pressure Support?

What is your humidity setting if you don't use "Auto" with the ClimateLineAir tube? You may be able to compromise between that and no humidity with a low humidity setting and the standard SlimLine hose.

Last night's data:

Average Pressure 7.78
Min Pressure 4.14
Max Pressure 13.66
90% Pressure 10.90

I use auto.

[OMyMyOHellYes]

I think I'm going to need to buy the DC-DC converter, because everyone I have spoken with at the various DME depts say that it is the only cable that works with my machine.

Yep. Resmed, IMO, is bad about that kind of thing for no apparent good reason other than to line their corporate pockets.

OMMOHY

[iSnore]

I've had good luck with the more affordable Chinese "Universal Battery" AGM brand. They're what Pride uses in their mobility scooters and wheelchairs, and are popular with a number of portable ham radio operators.

Using the example of a 100 AH rated model (# 12100). Using 80% of it could translate into 8 hours at 6 amps (some heat) plus 16 hours at 2 amps (no heat).

Last night's data:

Average Pressure 7.78
Min Pressure 4.14
Max Pressure 13.66
90% Pressure 10.90

I use auto.

That's most helpful. Interpolating a lot of the different usages from ResMed's Battery Guide, I do believe a [URL removed] 100 AH battery would let you go through the first night of an outage at an average of 8 cm, at least with a SlimLine hose and humidity on 3 or 4 and maybe even on auto with the ClimateLineAir tube, while leaving enough capacity for another couple of nights with no humidity if they didn't get power back the next day.

The regular [URL removed]Battery Tender Jr could take over 4 days to recharge the battery. I know that from experience, and the 750 ma rating confirms that. They make a [URL removed] 5 amp Battery Tender that could get it recharged in 16 hours or less, which would be healthier for the battery, but it's more expensive. You'll also need an [URL removed] adapter to connect the plug on the battery to the converter.

I wouldn't try to use anything other than the ResMed DC-DC converter on your ResMed machine.

Hope this helps.

Edit to add: I believe it's likely the ResMed machines and perhaps the converter have some parasitic draw when not in use. Until it is needed, I'd just have the Battery Tender charging the battery with the DC-DC Converter disconnected, and I'd use the 120VAC power supply on the ASV. When power went out, I'd replace the 120VAC unit with the DC-DC converter hooked up to the battery, but I would disconnect the converter from the battery during the day to keep it from drawing power when not needed.

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[archangle]

The regular Battery Tender Jr. could take over 4 days to recharge the battery. I know that from experience, and the 750 ma rating confirms that. They make a 5 amp Battery Tender that could get it recharged in 16 hours or less, which would be healthier for the battery, but it's more expensive.

If you need to quick charge the battery, for instance, at a friends house during an extended outage, get a different charger, more like a regular car battery charger. Use a special "maintainer" charger to keep the battery charged normally. I just don't trust any of the higher power battery chargers to do it right every time, 24/7, for several years.

The low power chargers can eat the battery slowly, but the higher power chargers can ruin the battery a lot more quickly.

[iSnore]

If you need to quick charge the battery, for instance, at a friends house during an extended outage, get a different charger, more like a regular car battery charger.

This may be a better option than upgrading to the 5A Battery Tender since you can get these chargers in a [URL removed] 10A or higher model.

Use a special "maintainer" charger to keep the battery charged normally. I just don't trust any of the higher power battery chargers to do it right every time, 24/7, for several years.

The low power chargers can eat the battery slowly, but the higher power chargers can ruin the battery a lot more quickly.

I agree with preferring a Battery Tender for 24 x 7 x 365 maintenance over trusting the higher power charger, such as the one I linked to above. That said, I've had our boat and RV batteries on good high-power 3-stage converter/chargers for years… but they're a lot more expensive.

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[AlanE]

A car battery can fail completely if you discharge it more than 60%. ...

Actually, a lead-acid 12v car battery is considered fully discharged when the open-circuit voltage reads 10v. Frequent full discharges will damage the battery. The plates will sulfate. I believe I read somewhere, when studying for an amateur radio test, that lead acid batteries will self-discharge at a rate of about 5% per month if not used.

Happened to my car battery when the alarm used to go off for no reason, all night. When it would no longer start my car I tried to recharge it. The battery eventually started spewing hydrogen at an impressive rate. Thankfully I had the sense to pull the charger plug out of the AC receptacle rather than disconnect the cable from the battery. Car batteries are the worst to use for solar systems. Spend the extra on a proper battery. Please, never use a car battery in the house with any kind of charger.

[iSnore]

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Oops… I had it backwards. I thought it was commercial links to CPAP Products/Vendors that weren't allowed. I apologize for linking to non-CPAP products/vendors.

Here are the ASINs
100 AH AGM Battery B00DDZEDZ2
Battery Tender Jr B000CITK8S
Battery Tender 5A B00HXC8SUW
Cigarette Lighter Outlet Adapter B0041CDPQO

[vsheline]

I've had good luck with the more affordable Chinese "Universal Battery" AGM brand. They're what Pride uses in their mobility scooters and wheelchairs, and are popular with a number of portable ham radio operators.

Using the example of a 100 AH rated model (# 12100). Using 80% of it could translate into 8 hours at 6 amps (some heat) plus 16 hours at 2 amps (no heat).

Last night's data:

Average Pressure 7.78
Min Pressure 4.14
Max Pressure 13.66
90% Pressure 10.90

I use auto.

That's most helpful. Interpolating a lot of the different usages from ResMed's Battery Guide, I do believe a [URL removed] 100 AH battery would let you go through the first night of an outage at an average of 8 cm, at least with a SlimLine hose and humidity on 3 or 4 and maybe even on auto with the ClimateLineAir tube, while leaving enough capacity for another couple of nights with no humidity if they didn't get power back the next day.

Two 50AH batteries (wired in parallel) would weigh about 32 pounds each, which is easier to move and set up than a single 60+ pound battery. At BatteryStuff dot com I have seen prices as low as $88 (plus shipping) for a 12V 50AH AGM Deep Cycle battery (UB12500-45977).

The ResMed 12V-24V DC-DC Converter is rated to deliver 90 Watt but may never need to deliver that much. Even if our ASV pressures were fairly high, the power drawn from the DC-DC Converter by the CPAP machine with humidification and heated hose may be closer to 80W. If DC-DC converter is about 90% efficient this would draw nearly 90 Watt from the battery. This would be nearly 7.5 Amp from a 12V battery.

The Ampere*Hour (AH) rating assumes a 20 hour discharge time and 25 degC temperature. A 100 AH battery is rated to supply 5A for 20 hours. The faster we discharge the battery the less Ampere*Hour it would be able to supply. For example a 100 AH battery would likely be able to supply 10A for 9 hrs, but certainly not 10A for 10 hrs. If we one wanted to be able to draw 7.5A current from a battery no faster than assumed by the 20 hour discharge rate, one would need a 150 AH battery.

With an ASV machine, and if using three 50 AH batteries (in parallel, forming a single 12V/150AH battery), I think this would probably be enough to last 8 or 9 hrs at 7.5A (fairly high pressure, full humidity and heated hose), leaving more than half the battery for perhaps an additional week (if changing to passive humidifier, without heated hose) before the battery would be nearly completely discharged.

That is, as long as the battery is kept above freezing temperatures. Batteries lose strength when very cold. Consult battery data sheet: http://upgi.com/Themes/leanandgreen/imag.../45977.pdf

[GeoffD]

Last night's data:

Average Pressure 7.78
Min Pressure 4.14
Max Pressure 13.66
90% Pressure 10.90

I use auto.

Those are very low pressure settings. You wouldn't need much of a battery to get a night or two with your humidifier filled with warm water but with the humidifier disabled. The $60-something 35 amp-hour AGM wheelchair/scooter battery would be plenty.

The HDM Z1 ultra-portable CPAP machine has no humidifier but they sell a disposable inline gizmo that absorbs the moisture from you exhaling into the mask. A Z1 Auto user and advocate on another CPAP forum uses them. They're $5.95 and he claims to get something like 10 days use out of them. You can find them on the manufacturer web site. HDM Z1Heat/Moisture Exchanger (HME).

I haven't bought one and played with it yet. I suspect you need to put it close as possible to the mask so it absorbs the most moisture. I'd have to hack up the hose to a spare ResMed AirFit P10 nasal pillow mask.