Yet another battery pack question

[Aeruginosa]

Here is the TL;DR version up front:
Will an Omnicharge 20 get me a nights sleep with my CPAP without damaging the CPAP?

Hi All!
I have recently discovered the forum and am plowing through the many posts/threads about battery packs. I have a couple of questions regarding a potential set up I have in mind and this forum seems like the best place to ask it.

I am interested in purchasing the Omnicharge20 for a variety of reasons, but the number 1 reason i will be purchasing a battery pack is for emergency CPAP usage during power outages as well as during camping. I use a Resmed Airsense 10 and my current plan would be to use DC to power the CPAP using resmeds DC adapter (https://www.cpap.com/productpage/resmed ... hines.html) and a Bix adapter coming out of the Omnicharge20 (https://www.amazon.com/gp/product/B007SP4KV0) .

One concern i have is that the DC adapter from Resmed is listed at 90W (stamped on the 'brick') and the DC output on the Omnicharge is rated at 45W. Is this a problem?

My next question deals with power. When using a Kill-A-Watt meter to analyze the power usage on AC power, It tells me that my CPAP draws 0.06 KW during 7 hours of sleep (humidifier and heated hose turned off). This is on AC power, so i don't know if there is any DC conversion to figure out if there is any difference in power usage. In your opinion, would the Omnicharge20 be able to power my CPAP for 1 night of sleep as described above?

To me, the beauty of the Omnicharge is that i can EASILY recharge it in a plethora of ways - AC or DC which means USB, wall warts, batteries, battery packs, and most importantly: Solar. There is also the ability to tightly control voltage on DC out. During camping or a an extended power outage, I would likely recharge battery packs using solar. I could have extra cheaper batterypacks (like $30 EasyAcc 20000 mah) to rotate with solar panel and recharge the omnicharge. Other features of the omnicharge make me think that this thing may be worth the extra money for similar powered battery packs for my use. That will not be the case though if i can't use it for at least a single night of CPAP sleep.

I am not 'rich' so I am also currently researching the Poweradd pilot 32000 mAh battery that appears often in the forum. Solar recharging is a big part of this plan and I am still searching for input specs on the Poweradd pilot (so i can know if / how to power it via solar (min. voltage / amp input and input barrel connector size)

I am not currently interested in AGM or LA batteries. I do not want to worry about draining a battery below 50%, and want the battery pack to indicate how much 'juice' it has remaining.

The new Goal Zero 400 lithium would be great and i think the goal zero sherpa 100 would work as well BUT - proprietary technology with Goal zero (their battery banks really only seem to play nice with their solar panels especially with cable connections) and co$t both have me looking elsewhere.

Thanks for any of your thoughts
(and I am not a shill for any company for any product(s) listed above lol)

[Goofproof]

Search for posts by CaptLok, he's our resident power person, check his posts for something close to your needs.

To me it sounds like you need more power than your money is willing to spend, a good portable power solution tends to be heavy and costly, as is solar. I don't have a link for your power supply but if you are drawing 90 watts, and you power source is rated at 45 watts, Houston, we have a problem. Charging from USB, wrong it will charge something small over USB. USB ports limited to .5 amp. A Remstar or other brand that uses 12 volt D/C are more power friendly. Jim

[Aeruginosa]

Search for posts by CaptLok, he's our resident power person, check his posts for something close to your needs.

To me it sounds like you need more power than your money is willing to spend, a good portable power solution tends to be heavy and costly, as is solar. I don't have a link for your power supply but if you are drawing 90 watts, and you power source is rated at 45 watts, Houston, we have a problem. Charging from USB, wrong it will charge something small over USB. USB ports limited to .5 amp. A Remstar or other brand that uses 12 volt D/C are more power friendly. Jim

I dont know what the 90W on the DC brick means(max rating perhaps?), but i do know that when using a Kill-A-Watt meter to analyze the power usage on AC power, It tells me that my CPAP draws 0.06 KW during 7 hours of sleep - thats 60 watts total for the night.

Here is a link to the DC Converter 24V 90W For AirStart™ 10, AirSense™ 10, and AirCurve™ 10 Machines: https://www.cpap.com/productpage/resmed ... ct-image-1

[CapnLoki]

The Omni 20 is a bit underpowered for the task. It has 20,400 milliAmp-hours, but thats at 3.7 volts. At 12V, its about 5.5 Amp-hours. We usually estimate an apap at 5 Amp-hours a night, but it depends on the settings, altitude, etc. Humidity and heated hose are out of the question for most batteries, and especially a small one like this. (That's where the 90 Watt spec comes from.) If you want to stay with small packs, 32,000 milliAH is better.

I know you don't want AGM, but at 1/3 the cost you can get triple the power, even with a 50% margin. If you only use the battery a few times a year, you could push that to 80% it it would still last 5 years. A small AGM (say 35 AH) would allow you to run humidity for a night it there's a power failure. If you really need to know the charge level, you can wire in a small amp-hour meter for under $20 - much more accurate. But I'd rather have 5 times the power to start. And remember, any battery can be charged with solar, but it only works if you have sun for 12 hours!

The 0.06 kWH is 60 watt-hours, which is 5 amp-hours from a 12V source. Actually this seems possible but a bit low - I've never trusted Kill-a-watt for accuracy of small devices. But assuming 90% efficiency of the power supply and an 8 hour night, its about the 5AH I guessed.

[Aeruginosa]

The Omni 20 is a bit underpowered for the task. It has 20,400 milliAmp-hours, but thats at 3.7 volts. At 12V, its about 5.5 Amp-hours. We usually estimate an apap at 5 Amp-hours a night, but it depends on the settings, altitude, etc. Humidity and heated hose are out of the question for most batteries, and especially a small one like this. (That's where the 90 Watt spec comes from.) If you want to stay with small packs, 32,000 milliAH is better.

I know you don't want AGM, but at 1/3 the cost you can get triple the power, even with a 50% margin. If you only use the battery a few times a year, you could push that to 80% it it would still last 5 years. A small AGM (say 35 AH) would allow you to run humidity for a night it there's a power failure. If you really need to know the charge level, you can wire in a small amp-hour meter for under $20 - much more accurate. But I'd rather have 5 times the power to start. And remember, any battery can be charged with solar, but it only works if you have sun for 12 hours!

The 0.06 kWH is 60 watt-hours, which is 5 amp-hours from a 12V source. Actually this seems possible but a bit low - I've never trusted Kill-a-watt for accuracy of small devices. But assuming 90% efficiency of the power supply and an 8 hour night, its about the 5AH I guessed.

Thanks for the reply. I am aware solar is inefficient. I do not want the thread to get derailed into solar - mentioned it only as i plan on using it to recharge batteries (and maybe i shouldnt have - the more that one mentions, the more it cluds the question sometimes lol)

I think the Airsense 10 is actually seeing 24 volts. I think that is what the AC and DC power bricks do (but not sure).

All i know for sure is the KillAWatt meter says 0.06 kWh used from the grid for 7 hours of sleep. There is no other battery pack that i have seen that is as user friendly to charge and discharge as the omni - thats why i want to know if it can make it through a night of 7hours sleep and do so with damaging either device.

[Muse-Inc]

I have a GoalZero Escape battery (no long made) that I've used during power outages. Works great! It was reviewed which stated it powered 2 nights (8 hr each) at pressure =12 without the humidifier. While I have 2 connectable solar panels, I've never used them so have no idea how long it might take to recharge the battery. Never needed to use it more than 1 night, thank goodness,

I am ordering a new recording oximeter (LED died on old one) that has an alarm I can set to wake me up if I start desatting. While I might have fragmented sleep, at least I won't desat IF I lose power.

[Aeruginosa]

I have a GoalZero Escape battery (no long made) that I've used during power outages. Works great! It was reviewed which stated it powered 2 nights (8 hr each) at pressure =12 without the humidifier. While I have 2 connectable solar panels, I've never used them so have no idea how long it might take to recharge the battery. Never needed to use it more than 1 night, thank goodness,

I am ordering a new recording oximeter (LED died on old one) that has an alarm I can set to wake me up if I start desatting. While I might have fragmented sleep, at least I won't desat IF I lose power.

Thanks Muse-Inc. That is a 150 Wh, 14,000mAh battery. That gives me some specs to compare but confuses me more. The Whr on the Escape is greater than the Omnicharge,, but the amp hour is greater on the Omnicharge.

[LoBattery]

I use an Airsense 10 without humidity off grid and these are my typical usage for four days at nominal 12V. Not going to look up that battery pack but as said before W = A times V and these numbers should follow.

12V BOOST INVTERTER

.55A STANDBY
.45A SLEEP
.05A BOOST CONVERTER ONLY

WH WP AH AP

63.8 17.7 5.14
62.0 22.7 5.02 1.7
71.5 25.5 5.79 2.08
60.4 19.6 5.08 1.57

[CapnLoki]

Thanks Muse-Inc. That is a 150 Wh, 14,000mAh battery. That gives me some specs to compare but confuses me more. The Whr on the Escape is greater than the Omnicharge,, but the amp hour is greater on the Omnicharge.

Amp-hours only have meaning when you know the voltage. Since all (most) traditional deep cycle batteries are 12V, its common to list the amp-hours for capacity and usage, and omit the voltage. Then Lithium packs and cell phones etc came along with a whole new world of "milli-amp-hours" where the voltage is 3.7 volts, the nominal for Lithium Ion cells. Lithium packs almost always have electronics controlling the cells so they can do things like put out a variety of voltages, so their true power rating should be in Watt-hours, which is voltage independent.

The Goal Zero Escape is actually an AGM battery, not Lithium. At 150 Watt-hours, it should be about 12 amp-hours at 12 volts, although they claim its a 14 Amp-hour AGM. Perhaps the down-rating it to keep a reserve to avoid damage. Rating it in milliAH was a marketing blunder since it looks like it has a third of its true power. It was essentially an upscale, pricey version of a small jump starter.

[CapnLoki]

I looked at the Goal Zero Yeti 150, the replacement for the Escpape
http://www.amazon.com/Goal-Zero-Portabl ... B00CWBABRM
Its the same basic setup, a 14 AH AGM battery, plus charger, inverter, various sockets etc for $200.

Its a bit upscale and pricey, but the reviews are good. However, since I'm always looking at the "bang for the buck" I notice that the 14 AH battery is smaller than the 18-22 AH batteries often found in jump starters for a lot less money. And, the bare essential system for a cpap would be a high qualtiy BatteryTender charger starting at $25, a $10 socket, and a battery - 14 AH starts at under $30, but I like the 35AH for $65. In other words, for half the money as the GZ 150, you can get twice the power. (The Omni20 is only 6AH@12V, so its half again as small, for even more money.)

Obviously, there are reasons why people buy the GZ or the Omni. If I wanted to use a cpap on a plane, I'd need something like the Omni - though I might go a bit bigger. If I was supplying a family with gadgets at a campsite the GZ might look good. But I still like the separate components for bang for the buck and simplicity. The BatteryTender is a last a lifetime charger, and it can be used to charge a number of batteries. The bare AGM batteries are cheap enough to throw away after a could of years, or to buy a small, medium and large, etc.

[Aeruginosa]

I looked at the Goal Zero Yeti 150, the replacement for the Escpape
http://www.amazon.com/Goal-Zero-Portabl ... B00CWBABRM
Its the same basic setup, a 14 AH AGM battery, plus charger, inverter, various sockets etc for $200.

Its a bit upscale and pricey, but the reviews are good. However, since I'm always looking at the "bang for the buck" I notice that the 14 AH battery is smaller than the 18-22 AH batteries often found in jump starters for a lot less money. And, the bare essential system for a cpap would be a high qualtiy BatteryTender charger starting at $25, a $10 socket, and a battery - 14 AH starts at under $30, but I like the 35AH for $65. In other words, for half the money as the GZ 150, you can get twice the power. (The Omni20 is only 6AH@12V, so its half again as small, for even more money.)

Obviously, there are reasons why people buy the GZ or the Omni. If I wanted to use a cpap on a plane, I'd need something like the Omni - though I might go a bit bigger. If I was supplying a family with gadgets at a campsite the GZ might look good. But I still like the separate components for bang for the buck and simplicity. The BatteryTender is a last a lifetime charger, and it can be used to charge a number of batteries. The bare AGM batteries are cheap enough to throw away after a could of years, or to buy a small, medium and large, etc.

The Yeti 150 would meet my needs but it has problems. 1) goal zero's propriety charging system 2) no way to turn off the low battery 'beeping'.

I appreciate you trying to save me money CapnLoki. You appear to be a good soul! I have been taking your advice into account here and in other threads as down the road i will build a battery bank with 6V batteries. I still dont know if the omnicharge20 it can make it through a night of 7hours sleep and do so with damaging either the cpap or the battery pack. LOL.

[CapnLoki]

The Yeti 150 would meet my needs but it has problems. 1) goal zero's propriety charging system 2) no way to turn off the low battery 'beeping'.

I appreciate you trying to save me money CapnLoki. You appear to be a good soul! I have been taking your advice into account here and in other threads as down the road i will build a battery bank with 6V batteries. I still dont know if the omnicharge20 it can make it through a night of 7hours sleep and do so with damaging either the cpap or the battery pack. LOL.

Hey, Chill! I already gave you the answer - its a big Maybe! First, its very unlikely to cause damage to the pump since you'll be going through a DC-DC converter that will take a wide range of voltages and convert to 24V, so it will be OK if you set the wrong voltage on the Omni. It might even be more efficient. The battery pack should protect itself against running flat, but that causes extra wear in the long run. As to whether it will go a night, the rated power of the Omni is slightly more than your reported use, so it will probably go a night. Of course, a lot depends on variables, such as the pressure, how deep you breathe, the altitude, if you're flying (the "cabin altitude"), temperature, etc. Since you're so close, you can't really tell until you try it. For instance, pressure 12 uses 20% more power than 10; battery capacity is down 10% on a chilly night, although the pump compensates for altitude, it uses more power. So what works on paper or at home might not work in real life. And, lithium cells often put out 105% rated power when new, then settle in to a slow decline, so it may work fine now, but not so much a year from now. This is why I usually recommend a large safety margin - 30% or more, even with Lithium packs. We eagerly await your report! BTW, the cells in the Omni are very similar, if not the same, as used in the Tesla S and X - 18650 cells in partnership with Panasonic. (The Model 3 went to a larger size.)

I'm not trying to push the Goal Zero (or any other brand), nor do I take a personal interest in your finances. I just like to clarify the pros and cons and costs of the various options, both for the present and the generations a-comin. Its easy to get sucked into the marketing hype or to get hung up on minor features. For instance, GZ has its own solar panels, but most any panels can by used since its really just a standard 12V battery. The Omni can be charged by any voltage which sounds real nice (and might be handy in some case) but in general you'll probably never use unless you lost the normal charging system. And you mentioned moving charge from one battery to another, but you should know that this is rather inefficient, maybe 85%, so it only makes sense going from a large battery to a smaller one. Also, you talked about only one night, but the buying decision is based on charging options - this leads me to think you're really thinking of longer camping and recharging daily. I have 25 years' experience with this - it only works with multiple forms of backup and overkill!

One more thing - I use 6 Volt "golf cart" batteries because when my boat was designed 20 years ago they were (and maybe still are) the cheapest deep cycles, so it has a battery box that holds 4 very neatly. Today, I would go with 12V AGM for most applications short of a whole house backup.

[nesdon]

Has anyone tested a variety of pumps to see if there is any significant range of power consumption? I've been using a Remstar Plus for about a decade, and am hoping to be able to replace it. I wondered if some models and brands are designed for more efficient operation.

I had used it on my boat, but it seemed to draw a fair amount, requiring me to run my engine periodically to recharge my house batteries. I now have a different boat with just a single house battery, I think it's about an 85 Ah AGM. I had also used it from my car when camping, so a similar capacity battery, but if I tried to get two nights out of it my car (albeit a VW diesel) would not start. That feels like more than the 5 Ah/night quoted here. Is this Remstar a very greedy unit? I was using 20 cm-h2o back then but am at 7.5 now so i expect better consumption. Any idea what the Ah/cm-h2o factor would be? I doubt it would be directly proportional. I am hoping to find a unit that is well suited to use on my boat in the future.

On another note, I have been using NOCO chargers for a while now and have found them completely bullet and idiot proof. I've never used their jump starters, but this 24 AH li pack https://no.co/gb20 weighs 1 lb and cost $65 on amazon. Their chargers are waterproof, with pretty sophisticated and complex charging algorithms, and comparably priced to Battery Tenders FWIW.

[CapnLoki]

Has anyone tested a variety of pumps to see if there is any significant range of power consumption? I've been using a Remstar Plus for about a decade, and am hoping to be able to replace it. I wondered if some models and brands are designed for more efficient operation.

The only comprehensive, product line wide document is from ResMed:
http://www.resmed.com/us/dam/documents/ ... lo_eng.pdf

I did a study of my Respironics 560, using a variety of settings, but only one pressure. Search the line in my signature - its re-posted in that thread. The anecdotal evidence suggests that Respironics is slightly more efficient than ResMed, possibly because it doesn't go through a 12 to 24 volt converter. That covers about 2/3 of the units sold. Small travel size cpaps seem to use 2/3 the power of full size, but so far they all seem to have compromises in noise and humidity, and/or custom battery packs.

Note that using the humidifier or heated hose will double or triple (or more) the load. Also, doubling the pressure roughly doubles the load, so the approximate 5 AH load quoted for pressure 10 can become 10 AH at pressure 20. Also, large leaks greatly increase load, as does altitude. I would guess that a large volume from deeper breathing would have a measurable affect.

One more thing - if you use an inverter, that will roughly double the load right there, as most inverters are about 60% efficient. Respironics can run directly on 12V (with the proper plug) and ResMed uses a 12 to 24 volt converter which is reported to be 90+% efficient. Its easy to see that a worst worst case of high pressure, humidity, altitude plus an inverter can tax even a large battery!

I had used it on my boat, but it seemed to draw a fair amount, requiring me to run my engine periodically to recharge my house batteries. I now have a different boat with just a single house battery, I think it's about an 85 Ah AGM. I had also used it from my car when camping, so a similar capacity battery, but if I tried to get two nights out of it my car (albeit a VW diesel) would not start. That feels like more than the 5 Ah/night quoted here. Is this Remstar a very greedy unit? I was using 20 cm-h2o back then but am at 7.5 now so i expect better consumption. Any idea what the Ah/cm-h2o factor would be? I doubt it would be directly proportional. I am hoping to find a unit that is well suited to use on my boat in the future.

In general, a cpap shouldn't be a large load for a boat battery. If the load is 5 to 10 Amp-hours a night, it is well within a normal house bank. However, if you only have one small battery, and if you have other loads, you may well have to recharge every day. Current setups use one battery exclusively for starting, and another as a house bank, so you won't get caught with two dead batteries.

As noted many times in this forum, using a car battery is a bad idea. A VW diesel is perhaps the worst case of a small (old?) battery and a hard to start engine, so its no surprise it led to failure! Its so easy to simply have a small mobility scooter battery, why take the risk? You might find using an extra battery like that on your boat is an easy alternative to enlarging the house bank.

BTW, I use a cpap on my boat for about 2-3 months of the year. Although I use humidity and heated hose at home, I've never had them on the boat since the ambient humidity is almost always over 60% - often over 90%! There have been a few late fall nights when I've regretted that!

On another note, I have been using NOCO chargers for a while now and have found them completely bullet and idiot proof. I've never used their jump starters, but this 24 AH li pack https://no.co/gb20 weighs 1 lb and cost $65 on amazon. Their chargers are waterproof, with pretty sophisticated and complex charging algorithms, and comparably priced to Battery Tenders FWIW.

The NOCO gear looks good but I'm disappointed that the battery pack specs omit the capacity of the battery! Doesn't give me a good feeling about the company.

[LoBattery]

I would add that AH rating of a couple year old battery can be illusive. The battery went bad in my car at work. I had another battery there, but when tested it was 0V. Put it on a little 6A charger. Took 30 minutes before it started drawing a charge current. After two hours I needed to get going so I decided to try it in the vehicle. It started right up. The lesson here is if the battery only has 20AH of capacity, you won't even notice it for a year or more. This is the reason those little Li battery packs on TV can start a car. Newer geared starters have a lot more power at less current. Just don't get Li cold.

I would suggest anyone using a battery get one of those little GT POWER type wattmeters which will tell you everything that happened with the battery that night. The best $10 you will spend.