High capacity Lithium-Ion Battery Packs

UPDATED! - See below

Hello,

New to the board. Sorry for the long and somewhat technical post.

I have been researching battery operation solutions for a while and have found quite a few helpful posts on this board (namely from JohnBFisher, kudos).

I am considering the CPAP Super Power Packs from http://www.batterypowersolutions.net and was wondering if anyone on the board had any significant experience using them. Their mid size model has 222Wh of capacity (about 20hrs of operation with my S8 and DC-12 adapter) and weighs in at a mere 4 lbs.

That said, I have several concerns about these power packs and the company marketing them (more on that below) and would prefer some real-life feedback before plunking down the 450$ or so for the mid-tier C-222 model. They don't sell these direct but here is a link to their product page so you can see what I am talking about: http://www.batterypowersolutions.net/Our_Products.shtml

My top 3 concerns:
First of all, the company promotes a 150W and a 225W pure sine wave inverter to go with their packs. The problem is that their 225W inverter is in fact NOT a pure sinewave inverter. This is misleading to the lay person and may cause an unsuspecting CPAP user to damage his unit (e.g. Resmed units with humidifier). Of course, this could be an honest mistake on their part but it sure doesn't give me a warm fuzzy feeling about their products or ethics. For those technically inclined the problem inverter is a Thor Manufacturing TH225 modified sine wave unit (http://www.thorpowerproducts.com/product/model-th225). I was not able to identify the make or model of their 150W inverter so I can't say whether it really is a pure sine wave unit or not. I asked them for a full specification but have not heard back yet.

Secundo, large Li-Ion/NiCd/NiMH battery packs are typically made up of multiple cells which need to be closely matched to prevent them from ageing and degrading at uneven rates. Otherwise, the power pack will degrade rapidly as far as capacity and achievable cycles, becoming useless in no time.

Finally, it is not clear to me whether or not I would be allowed to use the C-222 power pack in flight. FAA/DOT rules are fairly clear about being able to carry large battery packs on board as carry-on luggage but both FAA and DOT rules are silent on actually using large battery packs in flight. If anyone has used large battery packs with their cpaps (or other medical equipment) in flight, please let me know. I know that a few airlines have AC outlets at some/all seats but many don't and some who do won't let you plug in the CPAP in flight. I know this for having been in many of these situations personally. Hence the hunt for a battery pack that will allow me to sleep on overnight flights.

I know some of you are thinking " well just don't buy that product then, moron". Except that despite my concerns, these packs (if they actually deliver on their specifications) are a really attractive (and yes, expensive) solution. The capacity/weight ratio is fantastic compared to a lead-acid deep discharge battery like the one used by JohnBFisher for his project. That's why I'm still considering it. If I hear from actual users that have had good results with these packs, I will likely take the plunge... Without the inverter of course...

UPDATE - 2012-11-07

I purchased the the C222 Li-Ion pack (445$) along with the Resmed #33942 DC converter (112$) last September for a desert trek in the Middle-East last September-October. I used the pack on the overnight flight from Canada to Jordan (see more comments on in-flight use below) and of course on the desert trek. I also used the pack in the aftermath of hurricane Sandy, when we lost power for 2 days.

The pack size and weight are great, as expected. What is even better, is that runtime was greater than expected at over 35 hours when running at my average 10 cm H2O (Resmed S8 Autoset II). That means at least four 8-hour nights of autonomy with a 3lbs battery the size of a hardcover book (9.8” x 5.9” x 1.3”). This is almost double the estimated run time based on battery capacity (222Wh) and my S8 + #33942 DC converter current consumption at 10 cm H20 (0.84A as per Resmed battery guide). I am quite pleased with the performance to date and am looking forward to seeing how capacity holds up as the pack ages and cycle count increases. I have only put 6 charge/discharge cycles on the battery to date.

Regarding my top 3 concerns in my original post

1) Inverters:
Wrote http://www.batterypowersolutions.net about their misleading inverters advertising. They confirmed the inverters are modified sine wave units and said that nowhere on the web site do they claim they are pure sinewave . I sent them screen shots of their website with a bunch of highlighted sinewave claims. They just denied any wrongdoing and said they do their own testing so customers should be OK even though manufacturers like Resmed SPECIFICALLY say NOT to use the type of inverters they sell because they will damage their humidifier units. Not the best position for a supplier to have but since I don't use humidification when running on battery, it doesn't apply in my case. That said, I definitely question their business ethics but that is rather moot now that I have already purchased their battery and don't intend on buying their inverters. However, potential buyers beware of the false claims on their inverters. I suggested to batterypowersolutions.net that if nothing else, they simply add a warning to their inverter pages encouraging potential buyers to check with their CPAP manufacturer for any available guidelines and warnings about using their CPAPs with DC power inverters. Have not heard back since...

2) Quality of pack and cycle life:
Initial pack performance exceeded my expectations but it is too early to conclude on that. I need at least a few dozen cycles before I can assess pack quality and cycle life. I am pretty sure increased operating time is due to lower than expected CPAP consumption rather than a conservatively rated battery pack. Conservative rating is not really common practice amongst battery vendors

3) In-Flight use:
Did a bit of research on batteries allowed on board aircraft before taking the plunge and buying the pack. I chose the C222 pack because it passes the Lithium content limit imposed by airlines. The larger C444 battery pack CAN NOT be brought onboard aircraft. See the following link for details: http://safetravel.dot.gov/larger_batt.html. I could not find confirmation that large capacity batteries can actually be USED in-flight (not just carried) so, before the trip, I emailed the airline medical dept and asked for written confirmation that I can use the CPAP and Li-Ion battery in-flight. I included the specifications and details of the power pack, including Lithium content. They sent me a confirmation which stated it was OK to use the CPAP as long as it was battery powered (plugging into any aircraft power outlet was not allowed). I actually had to produce the confirmation email for the flight attendant to let me use the CPAP in-flight. Note that the attendant actually suggested I use the AC power outlet in my seat but I preferred to try the battery pack before my desert trek.

I also brought with me the Resmed supplied Travel letter and FAA compliance letter, as well as my CPAP prescription, just in case.

Conclusion:
Promising, lightweight, convenient battery pack for travellers, backpackers, hunters, fishermen, etc.
Espensive but the size/weight/capacity/features combination make it worth every penny for me. Remember that a good quality deep discharge sealed lead acid battery solution won't be that much less expensive once you have added all the features you get with the Li-Ion pack: charger, protection circuits for over-charge/discharge, short circuit protection, capacity indicator. Especially if you have a CPAP machine that can run off 12VDC power directly (no 100$ converter required). Add to that the weight+size difference and it is a no-brainer if you lead an outdoor lifestyle and can afford either solution.
Unfortunately, the selling company does not seem to have the best business ethics but they do offer a lot of support documentation and answer questions promptly.

Posting the same post over and over won't get a faster response, Most people won't use the battery pack because of the high cost, and iffy payback of that costly unit. Jim

The double-post was unintentional. Thank you for the reply.

I just used the Super CPAP Battery Pack (C-222) on a camping trip, and it worked great. I used it for 4 out of 7 days, for a total of about 28 or so hours, and it only used one of the lights on the 4-light charge meter. Since I didn't get a chance to use it until it was empty, I don't know how long it will really last, but if it actually was only about 1/3 to 1/2 way through, then that would be great. I got it because of the small weight and size, I didn't feel like hauling around and dealing with a 40-50lb. marine battery, and it was about 1/2 the price of the ResMed one. Of course, I also needed a 12 -> 24 volt DC converter so that I could hook it up directly to the ResMed, and that I got from ResMed. I should also mention that I use about 10cm of pressure, and was using passive humidification (turned off the humidifier heat, and used regular slimline tubing with the cover instead of the climateline tubing I use at home). I didn't get it direct from the manufacturer, I got it from a CPAP supply company, so I got a separate inverter (150W Tripp-Lite one) for charging the battery in the car in case I needed to do that. That didn't come up, since the battery didn't get low enough to have to charge it while I was traveling. I did use the inverter to charge my wife's camera batteries in the car, though *smile*.

At any rate I was pretty happy with it, and the voltage converter worked fine as well. The battery charger that comes with it isn't great, it heats up a little more than I'd like. But other than that, I have no complaints. I probably should return the charger for a replacement, but haven't done that yet. And I also need to get the battery out every couple of months or so until I use it again to top off the charge.

That's about all I can think of at the moment.

Once again, whenever I have a question all I have to do is turn to this forum! The information on the Super CPAP Battery Pack is much appreciated. I was planning to get a smaller version from ResMed, but this is an interesting alternative. My husband and I camp out both in boat and trailer, and we can use a car battery but I'd like the flexibility of the smaller battery. It would give us a backpack option -- although with machine, my pack would be pretty full! It sounds like this battery would outlast a car battery. We did buy a small Honda generator to recharge when camping without electricity, but I really like the idea of being freed from worrying about where to plug my machine in or having to be tethered to a car battery!

So can this battery plug directly into a Phillips Respironics System One?

I have a version of this battery and use it with my Devilbiss AutoAdjust. I had to buy the correct DC cord for my particular machine and you probably will need to do the same so tell them which machine you have.

By the way, I love the size and weight of this battery pack. I haven't used it except for one overnight but it was great and still has lots of charge left in it. The documentation that came with mine said that I just need to top off the charge every 3 months. I haven't had it long enough to do that even.

1. This appears rather high priced to me, but a couple of people already say this is cheaper since Resmed has a much higher priced model!! LiIo external battery packs for laptops (generic brands) seem to cost about $40 for a 72 amp-hr type. Sorry, I had seen them in stores like Frys, do not have a reference. This was made in China, where 90% of all LiIo batteries are made for all manufacturers world wide. These external battery pack are manufactured/sold in much larger volume, hence their lower price. [Also some selection and minor customization may be needed so it may not for everybody to go this route.]

After writing the above, I just googled for external laptop battery pack, and here is one I came across [This has 12v to 19v range]:
http://www.bixnet.com/unpowbat.html
I do not know anything about the quality of this product or its manufacturer.

1b. Of course you need to find one of those packs, that would match the voltage requirements of your cpap unit. BTW, two 12v packs (each of half capacity) connected in series would be a better solution for 24v needs than going through an inverter,because the invertors have about 60% efficiency. This means if you directly use the battery, you could actually use a 60% lower capacity battery than the one used with the inverter.

2. If the chargers are not made by a company w/ long term experience in LiIo charging, the batteries could be damaged by improper charging. This has been the cause of some lap top batteries failing in 18 months or so, a few years ago. But the chargers in laptops have got much better and more standardized now, resulting in longer life of about 4 years.

3. If there is overcharging, there is a non trivial probability of battery leaking or even exploding! This is one of the reasons airlines do not like them on board. Has anybody ever seen a LiIo battery explode? It is almost like a fireworks. I have heard of model airplane users who tend to fast charge their batteries experiencing this; fortunately they are often outside near open fields then

4. With the incorrect specifications of the product about pure sine wave, I would be concerned about the technical competence / product quality of this vendor and its products.

5. The need for a cpap on board the plane is somewhat exaggerated. Even on the very long international flights, (unless you have one of these fully lying down first class seats), the upright sitting position naturally reduces obstructive apneas and the need for cpap. I have been on multiple flights with cpap machine in my carry-on, and seat-side AC plugs. But did not feel the need to use them. Of course, everybody's apnea condition/severity is different.

feeling_better wrote: 1b. Of course you need to find one of those packs, that would match the voltage requirements of your cpap unit. BTW, two 12v packs (each of half capacity) connected in series would be a better solution for 24v needs than going through an inverter,because the invertors have about 60% efficiency. This means if you directly use the battery, you could actually use a 60% lower capacity battery than the one used with the inverter.

2. If the chargers are not made by a company w/ long term experience in LiIo charging, the batteries could be damaged by improper charging. This has been the cause of some lap top batteries failing in 18 months or so, a few years ago. But the chargers in laptops have got much better and more standardized now, resulting in longer life of about 4 years.

3. If there is overcharging, there is a non trivial probability of battery leaking or even exploding! This is one of the reasons airlines do not like them on board. Has anybody ever seen a LiIo battery explode? It is almost like a fireworks. I have heard of model airplane users who tend to fast charge their batteries experiencing this; fortunately they are often outside near open fields then

4. With the incorrect specifications of the product about pure sine wave, I would be concerned about the technical competence / product quality of this vendor and its products.

I also had doubts about using some random inverter on my CPAP machine, which is why I went with the 12 volt to 24 volt DC voltage converter from ResMed (for my ResMed CPAP). It was a less expensive solution, and helped me feel better about the whole thing. I would have gone with the ResMed battery pack if it weren't so outrageously expensive. Didn't even consider using 2 unknown quantity battery packs in series, which sounds fine in theory. And yes, I'm sure that there's some power loss in the voltage converter as well, but it seemed to me that the converter would be more efficient than an inverter, and that I wouldn't have to think about the AC waveform that a cheap inverter was putting out. As I said, the inverter is fine for charging the battery pack when driving in the car, as far as I'm concerned, though.

Anyways, this worked well for me, and I'm hoping that it will continue to do so. Yes, it was expensive, but everything that I ended up with has been well-reviewed and has been used by more than just me for this *smile*.

By the way, on the "top off the charge every 2 months", I called the battery pack manufacturer about that one, and that's what their tech support told me. This wasn't tech support in India or Malaysia, this felt like small company tech support, which can be in close touch with engineering and tends to be more reliable. You could probably do this every 3 months and have equivalent results, though *smile*.

feeling_better wrote:After writing the above, I just googled for external laptop battery pack, and here is one I came across [This has 12v to 19v range]:
http://www.bixnet.com/unpowbat.html
I do not know anything about the quality of this product or its manufacturer.

That one claims 42 Amp hours, but only 153 Watt Hours, so it's rated at 3.6V, not the 12V output. The "real" amp hour rating for CPAP use would be about 12 Amp hours at 12V.

They make some comments about that, and it sounds like it's common to publish fraudulent amp hour ratings by posting a per-cell amp hour rating. Using this false rating would make the "standard" deep cycle marine battery a 600 amp hour battery instead of a 100 amp hour battery. It sounds like this manufacturer is trying to be honest by publishing watt hours and the inflated amp hour rating his competitors use.

The problems with all lithium batteries are:

1) You MUST use the manufacturer's charging system and protection circuits. Rolling your own charging system can result in a fire.

2) You must have a properly designed control circuit that permanently disables the battery if it's overcharged or overdischarged, and shuts off temporarily if the voltage drops too low. The permanent disabling circuit prevents fires and explosions, and the temporary part keeps you from driving the battery into the permanent disable state.

3) The batteries may work very well, but they have a tendency to simply be 100% dead with no warning when you want to use them. Lead acid batteries tend to die slowly and give you plenty of warning if you pay attention.

4) If overheated or mechanically damaged, you can get a nasty fire. This is fairly uncommon these days, but can happen, especially with lower quality designs.

Lithium batteries are really great when they work right.

NIce. So for a solid overnight in a tent, with power available during the day, for a Philips Respironics machine that can take 12VDC, this seems like a great option, if I'm reading correctly.

Thanks for the info!

John

Note: I was recently informed that any item that qualifies as a CPAP accessory can be covered under a flex account.
--(YMMV)
Question: Is a charging device included?

This thread popped up conveniantly. I was just looking at a possible solution for a light weight Lithium-Ion battery for my CPAP, to use in flights, on over night train rides, fishing trips etc.

http://dx.com/p/12v-9800mah-rechargeabl ... tery-90998

This battery pack has 9.8 amp hours, that is 117,6 watt hours. If the C-222 runs a Resmed S8 CPAP for 4 night with a DC converter, this one should be good for at least a couple of nights with a CPAP that accepts 12 volt directly.

I have an itchy trigger finger, what do you think?

Let me see, Burke; free shipping from DX to Nebraska takes close to a month.
I wonder how long it takes to Norway.
I found a better price on the cpap battery:
http://www.cpapbatterystore.com/C-222_details.html