My back up power set up questions UPDATE

[sleep_quest]

I'll admit my ignorance right up front...I've been following the various backup power posts with the hope of finding just the right set up that would work for me at home however, I get glassy eyed with some of the technical jargon.

While I appreciate all of your expertise and input I am now heading towards the dreaded glassy eyed condition...

I understand the need to be very careful around electricity and to advise others to do the same when you are offering your opinions. But right now with the conversation between CapnLoki, Guest and Archangle I'm confused as to what is educated opinion and what is fact and whether to get bogged down in the off topic conversation.

In an attempt to steer the conversation back to my original post, let me start with:

The Duracell manual says:

1. "Once fully charged, the charging current automatically reduces to a maintenance charge mode, and the Duracell Powerpack Pro may be left permanently connected to the AC cord." "All rechargeable batteries gradually discharge when left standing, and you need to recharge them periodically to maintain maximum battery capacity. The charger within the Duracell Powerpack Pro is designed to regulate the charging process, ensuring that the battery is always fully charged but never overcharged..."
2. "Connecting to an external battery: You can extend battery operating times by connecting the Duracell Powerpack Pro to a larger external battery. For example an external 54Ah battery gives approximately 3 times the operating time of the Duracell Powerpack Pro internal 18 Ah." The manual goes on to describe connecting the powerpack using the jump-start cables: first making sure the jump-start power switch is off then connecting the red positive clamp to the positive (+) terminal and black negative clamp to the negative (-) terminal. Then turning the jump-start power switch on.
3. "As the DC power outlet is internally wired to the Duracell Powerpack Pro's battery, extended operation of a 12V DC appliance may result in excessive battery discharge. "The DC power outlet does not automatically switch off when the internal battery is discharged. Check the battery status periodically to prevent total battery discharge."

I hope that I can trust what Duracell tells me as these are the principals on which I based some of my design. I will leave the powerpack plugged in so that it is always fully charged and if I do need to use the powerpack, I will unplug the AC first, use the powerpack and then plug it back in to recharge once I'm done. When using the DC connection I will also periodically check the battery level of the powerpack to avoid a total battery discharge and will recharge it after each use. I am comfortable with handling the jumper cables and connecting to an external battery when and if the time comes. If 'the big one' happens and we are without power for a number of days I will follow #2 above making sure to protect the cables and terminals from inadvertent contact with each other and any other metal (read NO SCREWDRIVERS, CATS or BREAKFAST TRAYS ALLOWED ) and I will not have an open flame or flammable liquid in the area either. It actually helps to write this out and say it out loud so that these 'rules' are now part of the drill so thanks for that!

I think the big issues left on the table are how to charge the powerpack and the external battery in the case of an extended outage and this is where I get skittish with the statements made so far. I believe we have a consensus that I can recharge both batteries using my car; by using the DC outlet for the powerpack or by attaching the external battery to my car battery and then turning on the car and letting it run. Using a car may not be ideal depending on my fuel levels but that will work. I can always get a generator or a solar panel (yike$) but if I want to charge my powerpack using the jumper cables and car I am potentially risking damage to my home and/or the powerpack (or not, depending on the contributing sources). Have I boiled this down correctly?

I get that any path I choose comes with risks but I can't account for every possibility of failure so what I'm looking for is a relatively safe battery charging design that will bridge the gap in the case of an extended power outage (preferably without blowing my home up in the process)? I apologize if I'm being dense here but this topic is not my forte yet I still need to accomplish my task. Anyone else have any practical experience with this topic?

thanks,
d

[sleep_quest]

Theory and speculation often provide very interesting topics for discussion. However actual use generally brings things into sharper focus and you can then focus on the things that matter the most while also keeping in mind the bigger picture involved with the theories.

The idea is that if you push high current back into the jumper battery you could encounter problems. In actual practice as the current goes into the battery the voltages rises. When the voltage rises the current tapers off. This means that it should not be a "real" issue even though it could be construed as a theoretical possibility.

Also, over many years of using jumper packs and jumper batteries and charging them from the vehicle charging system after it got started I have never had an issue with hydrogen gas formation or exploding batteries as a result.

Of course your mileage may differ. It is important to be aware of the theory that something could possibly happen but in actual practice it is very remote that it would happen.

Thank You Hosecrusher. I guess you posted while I was writing my last 'term paper' . I'm glad I'm not the only one who thought the topic was drifting into Theroyland and therefore was not getting a more 'practical' response. I do appreciate the theories but I need a practical solution so thank you for your many years of using jumper packs and jumper batteries worth of experience!

d

[Guest]

"Once fully charged, the charging current automatically reduces to a maintenance charge mode, and the Duracell Powerpack Pro may be left permanently connected to the AC cord."

That is correct and I'll go one further - I plug my machine into my jump starter while it is plugged into the AC charger and have for years. It acts just like a UPS w/o all the alarms when the power goes off. I have slept right thru power outages cuz you don't miss a beat.

Now when the power goes off I can at least go to sleep.

Is that practical experience enuff?

I told you how I charged my jumper on the car. I actually had 3 hooked up at one time. It would take days on a gas generator and using the AC charger. The charger is good for maintaining the charge level but takes forever when the battery gets low.

[sleep_quest]

Guest wrote

sleep_quest wrote:
"Once fully charged, the charging current automatically reduces to a maintenance charge mode, and the Duracell Powerpack Pro may be left permanently connected to the AC cord."
That is correct and I'll go one further - I plug my machine into my jump starter while it is plugged into the AC charger and have for years. It acts just like a UPS w/o all the alarms when the power goes off. I have slept right thru power outages cuz you don't miss a beat.

Now when the power goes off I can at least go to sleep.

Is that practical experience enuff?

I told you how I charged my jumper on the car. I actually had 3 hooked up at one time. It would take days on a gas generator and using the AC charger. The charger is good for maintaining the charge level but takes forever when the battery gets low.

Yes you did Guest, you were the lone voice in the woods offering up that advice before the conversation got bogged down. And, you made me feel like I had a good plug and play design and defended my desire for it. Thanks for that. For what it's worth, I would have felt more confident in your advice if you were a known entity and not a guest. I prefer to pose specific questions to users who I have had some previous interaction with or with whom I have a sense for from their previous postings but in your case I don't have that luxury. I can't PM you with follow up questions and I don't have anything to go on other than the info you provided in my topic (as helpful as it was). I have no idea how many 'Guests' there are providing advice from their experience and can't assume all 'guests' are the same person (gee I hope all the 'Guest' posts in my topic were from the same person/you...). Why not register? Just wondering...

[Guest]

Why not register? Just wondering...

Have you seen the fanfare here? Think I want to be one of them?
As Snoredog said I don't talk in PMs.

I am here to help not be helped.

If you haven't already read it search for "My Camping Battery Box", he says he got 10 days from his setup and that sounds like what you are looking for.

[Guest]

You can also search for a thread titled "Another Battery Option" - he uses a jump starter. It might be a long read but you can see the very same naysayers in there telling him it wouldn't work. He just ignored him and posted updates for a couple years.

Just the same darkclouds all over again, unfortunately. You start to see a pattern?

[sleep_quest]

Thank you Guest. I'm not sure how I missed that "My Camping Battery Box" post (thanks mshilko!) because it addresses my needs very well, especially the need to be portable which I wasn't quite ready to tackle! And it has detailed instructions and pictures to boot! I won't need to add the USB ports so I'm hoping putting the battery in the box is as straight forward as it looks and I should be all set. I can still use my powerpack for short term needs and recharge both with the automatic battery charger or a car as needed.

It looks like the term 'building a battery box' does not need to be as scary or time consuming as I'd imagined. While I had visions of having to "solder, weld, wire or otherwise construct" this mythical box I didn't pay attention to a key statement in one of CapnLoki's posts

Building such a box is really simpler than many of the posts make it out to be. The only issue is connecting to the battery, since each battery will have it's own style of terminal. Once you deal with that, there are wiring harnesses available that complete the job with appropriate fuses and socket. The "Battery Tender" charger I've mentioned comes with most, if not all, of what you need. Add a $5 box and you're good to go. For smaller batteries you can get by with slide on clips if they're insulated and the terminals are protected,

I was focused on the "Once you deal with that, there are wiring harnesses available that complete the job with appropriate fuses and socket..." part of the message not realizing I could buy a box that had everything already built in (so it doesn't cost $5 or $8, to me the $60 'plug and play' version is worth it).

Life just became a little less complicated...
d

[archangle]

The idea is that if you push high current back into the jumper battery you could encounter problems. In actual practice as the current goes into the battery the voltages rises. When the voltage rises the current tapers off. This means that it should not be a "real" issue even though it could be construed as a theoretical possibility.

When you hook up a small discharged jumper battery to a large, fully charged lead acid battery, the resistances, current capabilities, electrochemical reactions in the battery will find a point of balance. You will start with a high current and low voltage at the smaller battery. As the battery charges, the voltage will go up and the current will go down. They'll eventually reach the same voltage and current flow will stop.

The question is whether the current is high enough for long enough to damage the smaller battery. It's definitely possible to damage a lead acid battery with too high of a charging current.

Look at it this way. The jumper battery is a cow. The car battery is an elephant. Chain them together. If the cow tries to pull an exhausted elephant, not much bad happens to the elephant. When the elephant pulls an exhausted cow around, bad things happen to the cow.

Also, over many years of using jumper packs and jumper batteries and charging them from the vehicle charging system after it got started I have never had an issue with hydrogen gas formation or exploding batteries as a result.

How many times have you connected a severely discharged gel cell battery to a fully charged car battery and left it connected for an hour or two? If the jumper battery had enough charge to start the car, it's not going to be deeply discharged.

The real danger is if the jumper battery has developed shorted cells, which commonly happens with old batteries. If you connect the damaged battery to a real charger, the charger will only produce a limited current. A car battery can produce hundreds of amps.

[archangle]

You can also search for a thread titled "Another Battery Option" - he uses a jump starter. It might be a long read but you can see the very same naysayers in there telling him it wouldn't work. He just ignored him and posted updates for a couple years.

Just the same darkclouds all over again, unfortunately. You start to see a pattern?

Yes, that one jumper battery and charger worked with that one CPAP machine for one user for a limited amount of time. I'm not surprised. 99 times out of a hundred, a drunk driver makes it home without killing anyone.

I might risk using a jumper battery with the charger attached myself, especially since I have a spare CPAP machine. I'm not going to tell you that a every jumper battery with a charger is going to work well for every CPAP user.

[Guest]

You have to truly be the most unhappy person I have ever met. You deprive yourself of sleep to scour the internet to tell people you are the brightest bulb. Well, I am not convinced

Yes, that one jumper battery and charger worked with that one CPAP machine for one user for a limited amount of time. I'm not surprised. 99 times out of a hundred, a drunk driver makes it home without killing anyone.

IIRC, he covered at least 2-3 yrs and prob left because of people like you. Yes, you are one of the naysayers I recall from that post.

Wasn't it you who told Tom Edison it wouldn't work too.

The people who exaggerate the dangers of insignificant or nonexistent risks get people killed because they draw attention away from the actual health risks.

[CapnLoki]

...
It looks like the term 'building a battery box' does not need to be as scary or time consuming as I'd imagined. While I had visions of having to "solder, weld, wire or otherwise construct" this mythical box I didn't pay attention to a key statement in one of CapnLoki's posts

Building such a box is really simpler than many of the posts make it out to be. The only issue is connecting to the battery, since each battery will have it's own style of terminal. Once you deal with that, there are wiring harnesses available that complete the job with appropriate fuses and socket. The "Battery Tender" charger I've mentioned comes with most, if not all, of what you need. Add a $5 box and you're good to go. For smaller batteries you can get by with slide on clips if they're insulated and the terminals are protected,

I was focused on the "Once you deal with that, there are wiring harnesses available that complete the job with appropriate fuses and socket..." part of the message not realizing I could buy a box that had everything already built in (so it doesn't cost $5 or $8, to me the $60 'plug and play' version is worth it).

Life just became a little less complicated...

Yes, the Minn-Kota box that I mentioned a few posts back is pretty slick.

OK, perhaps the $5 box is a bit dated. But Walmart has several around $8. While there, check out the "MinnKota Trolling Motor Power Center" which includes cables, socket, breakers, etc. Add a battery and a "Battery Tender" and you're all set. With very little work you can have a high quality, 80 AH AGM backup, good for several weeks of service for about $300 total. Not too bad since the OP was talking about Lithium that would be $300 for 20 AH.

Inside it has connectors for the "wing-nut" style posts common on deep cycle batteries.
https://www.youtube.com/watch?v=-2J6jBt1nFI

A few points: I've recommended the "Battery Tender" charger. The make two versions: the Junior (about $25 with 0.75 Amp output) is good for keeping a battery that is used occasionally topped up. The Plus (about $50 with 1.25 Amps) is better if you needed to charge a bit faster. Both come with the cables to connect to the Minn-kota box. By comparison, the Duracell claims 1.5 Amps bulk charging. Any of these will take several days or more to get a larger battery well charged.

Some people use the Duracell jumpstarters or the Minn-kota (or homemade equivalent) as a Uninterruptable Power Supply. This will work fine with no humidity, but since the charger can only supply about 30 Amp-hours a day, if you use full humidity you will be running the charger continuously, and maybe falling behind. Evaporating a full humidifier chamber on a Series 60 takes about 20 Amp-hours of juice. For faster charging, something like the 5 Amp Minn-kota charger would be good. A larger battery can charge even quicker - the Trojan 24-AGM I've mentioned is a very conservative 76 Amp-hours, and can probably accept 20 Amps. Personally, I would use the normal power supply most of the time, keep the backup (which ever version you pick) in the corner on a trickle charge, and be prepared to use a car as a high current source to charge at whatever the battery can accept. But if power outages are very frequent, a UPS is handy.

I've been thinking about your "solder, weld, wire, or otherwise construct" comment. The biggest problem comes when connecting to a battery. Marine style deep cycles often have a post that matches the ring connectors that come with the Battery Tender, but smaller AGM or Lithium batteries have spade or other connectors. You can always go to a Radio Shack or radio control model shop, marine electronics etc, and have them quickly make up the appropriate cable - $20 should be more than enough to pay some kid for 10 minutes work! (Or if you have a friend with a larger boat who does his own work - he probably has a crimping tool.)

[sleep_quest]

CapnLoki:

A few points: I've recommended the "Battery Tender" charger. The make two versions: the Junior (about $25 with 0.75 Amp output) is good for keeping a battery that is used occasionally topped up. The Plus (about $50 with 1.25 Amps) is better if you needed to charge a bit faster.

FYI, I went to my local Costco last night and they have the Battery Tender Pro for $39.99.

And while I was there I topped off the ol' gas tank so I have plenty of fuel if I need to charge my powerpack battery anytime soon.

[PlinkerCraig]

I actually tried to see if I could push some charge back into a jump-pack through its jumper cables. My conclusion is that for product safety reasons they built in a diode to prevent current flowing into the jump pack through the jumper cables that are meant to source current.

Has anyone done a serious measurement of the amp-hour draw of the original poster's Respironics 560 machine yet? I'm tempted to rig a fixture to measure this since I have one of the 560 machines. I'm an electrical engineer working in the test&measurement field for 30 years now so I think I know what I'm doing, but somebody here may contradict me if I get results that don't meet layman's intuition. Is it worth me taking the time to do this measurement? Let me know.

Back to the original question. I have the same Respironics 560. I'm a cheap assed bastard, so I bought a 100 amp-hour deep cycle marine battery at an auto parts store for $105 and I got the DC cable set from Respironics just like the original poster did too. Now it will be nifty to characterize how many hours of operation I get with or without the humidifier. I think I'll skip characterizing over different cmH20 settings since I can't imagine how to do that accurately and safely by myself.

[HoseCrusher]

archangle, I run into situations like this frequently. Last week I had to jump 4 vehicles. This week only 2. A loose average is 2 - 3 times a week. In each case I let the jumped vehicle recharge my jump pack and have not run into any problems so far.

It seems that elephants and cows actually play well together...

PlinkerCraig, My jump pack actually allows for charging through the jump cables. I have a battery minder that I use to charge the gel cell once a month or so just to keep everything topped off and always use the jumper cables for the hook up. The idea of incorporating a diode seems safer but it would require me to adjust my current usage. I use an external charger because I don't trust the built in charger. If the jump pack came with a decent charger that would help.

[sleep_quest]

PlinkerCraig

Has anyone done a serious measurement of the amp-hour draw of the original poster's Respironics 560 machine yet? I'm tempted to rig a fixture to measure this since I have one of the 560 machines. I'm an electrical engineer working in the test&measurement field for 30 years now so I think I know what I'm doing, but somebody here may contradict me if I get results that don't meet layman's intuition. Is it worth me taking the time to do this measurement? Let me know.

For my own selfish reasons I'd appreciate knowing what the 560 draws and thus know the limitations I am working with. If this information isn't readily available and you're offering I'm gonna say YES PLEASE...

thanks,
d