[Product Review] Gissaral GIS09B-AP3 lithium-ion battery pack (power bank)

[Fats Drywaller]

Product:  Gissaral GIS09B-AP3 portable lightweight battery pack, typical retail price $80.

Rating: Three stars.  Would otherwise deserve 5, but loses one star for not being 12V chargeable, and loses another for not defaulting to 12V output via its 12V/15V jack, which is hazardous to devices that could be damaged by the slight overvoltage.

My post copied from a "canoe camping" thread in the main AB forum follows:

I found a fairly good (for my purposes) cheapie Li-ion battery to provide 12VDC for only one night at a time, at up to 5A peak (startup): the Gissaral GIS09B-AP3, 130 watt-hours, weight 1.4 pounds, about $80 at Amazon (search for "Gissaral 35000mAh power bank external battery portable charger").  That watt-hour figure is assuming that the stated capacity of 35 amp-hours is at 3.7V, which seems to be the practice of the various manufacturers when publishing those numbers, presumably because each Li-ion cell puts out 3.7V.  (I'm not an expert, let alone an EE, so it's news to me.)  Using its 12V output, the thing should give a solid 8 or 9 hours of CPAP use at a sustained draw of 1A (no heater, of course!) without completely draining it, and in my initial testing at home, it does that.  The stated charging time is 4 hours maximum using the included AC brick (fairly light, about half a pound) with its 15VDC output, or 15 hours through a 5V micro-USB power-in port (fuggedaboudit).  The battery has outputs of 5V via several USB jacks and 12V or 15V via the usual 5.5x2.5mm jack, so you can also use it with your phone, tablet, laptop, etc.

The fast-charging input is labeled "15V-20V", and I guess for motor-vehicle travelers (I'm not one) it must be a serious flaw not to be able to use 12V to charge it, so presumably that would rule out this product for those folks?  If so, then use this post only as a general outline of what's possible, and look for a similar but better product that can be charged from 12V.  Or else, I guess, do use this product but plan to use an inverter to charge it, further increasing your friendly local entropy.  But there are others to choose from, and I'm not intending to imply that the Gissaral is special or wonderful.  I chose it because I liked its combination of medium capacity, low weight, and moderate price.  For my purposes (which don't include 12V charging), I think it's pretty good value for the money.

So anyroad, the Gissaral unit, and many similar ones from various mfrs, can be paired with the Battery Power Solutions 24V Power Converter for Air 10/S9 Series and Freedom or C-100 CPAP Battery (Az search), which is around $70 at Az, maybe slightly more at some of Suppliers #1 through #n.  That's one of several available converter devices providing the Resmed secret Masonic handshake on pin 3, and I think (someone correct me if I'm wrong) that it's the only one other than Resmed's that is sold as a separate component, without a battery pack.

Gissaral and BPS devices, large images behind thumbnails, courtesy of the manufacturers:

That old photo of the Gissaral has a DC-in jack labeled "16.8V/20V", but the unit that I bought recently has "15V-20V" and its AC adapter puts out 15V at up to 4A.

I'm glad that BPS does sell that Resmed converter separately, but I'm also bugged that its price is ridiculously high.  I'd still rather pay $80 + $70 = $150 than a total of $330 for the BPS Freedom kit with a 97 Wh battery, even though that one has a nice digital display ... or $340 for the Medistrom Pilot-24 (also 97 Wh), or $265 for the Bixpower CP170-S10 (higher capacity ... 159 Wh?), or $250 for the Powermod "Knyte Power".  All of those products include a Resmed-compatible 24V converter, but I'm enough of a cheapskate and just barely enough of an electronics tinkerer to balk at those prices and to plug together an equivalent kit from off-the-shelf components.  And if you think those four are overpriced, try $700 for the Resmed Power Station II.  The operative principle seems to be "Never give a sucker an even break, and never smarten up a chump."  (I do know how that goes from a chump's point of view; over the years I have paid unreasonably high prices for a few items of consumer electronics, as I'm sure most of us have at one time or another.  I just didn't want to add another item to that list, thus my recent consumerdroid research ending, at least for now, in the selection of the Gissaral gizmo.)

What gets me about the price gouging is that a DC-only power supply doesn't have a Medicare HCPCS number and isn't considered essential equipment by the insurers, so you pay for it yourself.  That point is even in BPS's own FAQ.  (Of course, BPS is doing great by cutting Resmed's retail price in half; end of story, right?)

I haven't bought the Resmed-compatible converter yet, so initially I'm testing my Gissaral at home with a De Vilbiss DV54, which is in the IntelliPAP 1 series (not IntelliPAP 2, whose power requirements are different).  With the DV5x machines, a straight-through power cable from the battery's 5.5x2.5mm jack to the DV's 5.5x2.1mm jack, 12VDC with the usual tip positive, is all that's needed.  The DV5x automatically disables its heater (assuming that the humidifier base unit is attached to begin with) when using DC power.  Depending on how you're providing the DC power and whether you want heat, that could be good or bad.  With a small Li-ion battery, it's good, or at least necessary, and you can still use passive humidification.

The battery will also work with other machines that can take 12VDC, including Philips Respironics.

ISTR that it was OMMOHY who pointed out here a while back (and it's in the user's manual) that De Vilbiss machines include the circuitry to implement a UPS if you have both AC and DC power plugged in, so that's a plus for use at home.  OTOH, the automatic switch to DC will disable the heater for the duration, so that might wake you up or give you bad dreams even though there's no audible power-loss alarm as there is with most UPSes.

How this exercise in creative shopping got started was that I've been super-disgusted with all four of the available portable/travel CPAP machines, I refuse to buy any of them, and therefore I'm stuck with what I've got (full-size machines) both at home and at large.

Here are some further items of trivia learned while browsing & reading:

• The standard first step in psyching yourself down for this, if you'll need to use a lightweight battery, is to forget about the humidifier heater and the heated hose: get over it!  In eschewing (I've always wanted to use that word) the humidifier entirely, I have learned to occasionally put up with a very minor nosebleed, from all that dry air, for a few minutes after waking up. (So any hemophiliacs out there in readerland should not try this; they should keep using the heated humidifier. Find a DC power source with a much higher capacity, or else stay home.)
  
• With the Gissaral, before plugging in the DC-out cable, be sure to switch the 12V/15V output to 12V by pressing the button a couple of times until the LEDs go from green to red.  Green = 15V (default); red = 12V.  You have to do this every time you use the damned thing, so that's a minor gotcha.    It could be worse than minor if you forget to switch it and thereby let some magic smoke out, so that's another reason (besides the lack of 12V charging) to look for a battery that's better than the Gissaral.
  
• With a Resmed-compatible converter box, no matter what power source you use, you need to give the converter its DC power feed before plugging the 24V output into the CPAP machine, otherwise it won't work and the machine will play dead.  I assume that must be FAQ #1 for all of those Resmed-handshake products.
  
• Of course, use a voltmeter to check the voltage & polarity before plugging together a home-brewed setup for the first time, and compare those with what your machine and the 12-to-24 converter are expecting, and modify your cables & connectors if necessary.
  
• Some power cables with 5.5x2.5mm plugs on both ends are foolishly advertised by clueless sellers as also fitting 5.5x2.1mm jacks just because the outer diameters are the same, but I don't recommend ever using that, because the center connection at the 2.1 end will be intermittent and flaky.  Go for an actual 2.5-to-2.1 cable.  Otherwise you can kluge one together from a same-connector cable and a different-connector plug-and-jack attachment, for instance "Longdex DC Power Adapter 5.5x2.1mm Female Jack to 5.5x2.5mm Male Plug" (Az search).
  
• I considered and rejected the Talentcell YB12011000, 132 Wh, 1.5 pounds, $65 ... rejected only because the manufacturer's description says that to extend the life of the battery, it's designed to use a slow charge: 10 hours!  Maybe OK for use in a motor vehicle with all-day driving.
  
• Also rejected for now was the well-known Maxoak or Poweroak K2, $100 to $140, advertised as 50 Ah (185 Wh?), also sold re-badged as GBTiger and Renogy among others.  For me, it's too heavy, about 3 pounds.  Except for the weight, that product looks good because of its high capacity.
  
• The XTPower MP-50000, 195 Wh, $200, 3 pounds, is also overkill for me, but probably useful to many other CPAP users.  That's the one I would go for if weight & size & cost were not so important to me.  (Added later:  One reviewer said that he got three nights of CPAP use out of it.)
  
• The XTPower XT-20000QC2 at $80 is great except that its capacity is only about 75 Wh (as is obvious from the 20000 mAh number in the product name).  I wish there were a mid-range XTPower model, 35000 mAh.  That would be the one for me, because I am impressed by the XTPower devices in general just from reading the specs & reviews.
  
• There are many other makes & models of "power bank" that have only 5V USB-jack outputs and are therefore no good for us.
  
• Engine-starting batteries like the Micro-Start XP-1 (and many similar) are also not appropriate for CPAP use.
  
• The Medistrom Pilot-24, besides being overpriced, uses the Resmed machine's heavy power brick for charging ... another situation where it's not a big deal as long as you're using a motor vehicle to carry everything around.
  
• The Resmed part # 37297 12-to-24V converter for the A10 and S9 is too bulky for my purposes and I didn't want to have to cut off the cigar-lighter plug and attach a 5.5x2.5mm plug; thus my choice of the BPS item instead, at about the same price.
  
• An updated edition (August 2018) of the Resmed Battery Guide is available on the Resmed web site here (PDF).
  

Non-commercial disclaimer:  I have no affiliation with any of the manufacturers & suppliers mentioned in this article, except as an anonymous consumerdroid.

[Fats Drywaller]

I can't resist adding a mention of an accessory to go along with any battery pack: a kit of 38 power-plug tips.  Some battery products provide a bunch of those, but others, including the Gissaral, don't.  The Amazon page title and search phrase for the one I have in mind is "aceyoon Laptop DC Power Adapter Kits 38 PCS Universal 5.5 mm x 2.1 mm DC AC Power Adapter Tips", about $13.  (You'll also need a 5.5x2.5mm to 5.5x2.1mm cable, M-M.)  I just think it's amusing that there are 38 of 'em.  It reminds me of "The wonderful thing about standards is that there are so many to choose from."

Large image behind clickable thumbnail:

[Fats Drywaller]

Earlier, I wrote that the Gissaral battery should default to 12V from its 12V/15V output, but obviously I was in a hurry and not thinking straight, because that would just put the burden of checking & switching onto the folks who need the 15V output, rather than 12V, to charge their laptops.  (OTOH, defaulting to a lower voltage is much better and less hazardous.)  What all of those battery packs should really have, and omitting this is a serious oversight, is a hardware switch, not a software (firmware) switch, to select the voltage from the one shared output jack.  It should be possible to set it and forget it.

I was reminded of that when I was browsing a description of a similar product, the "Krisdonia 50000mAh Laptop Power Bank External Battery with QC3.0 Quick Charge 3.0 Portable Charger for Laptop, Smartphone and Other Digital Devices" (Az search string), whose description says: "One DC-OUT 5V 8.4V 9V 12V 16V (16.5V) 20V (19V, 19.5V) for different laptops.  (When you charge your laptop with DC-OUT, first please adjust the voltage of the power bank.)"  Gee, thanks a lot, you clever device designers!  So once again the user of the stupid thing has to be careful not to fry the device that he's powering or charging, every time he uses that poorly-designed battery pack.  That lack of a hard switch (a multi-position slide switch, preferably recessed) to set-and-forget is a bad misfeature.  (In other words, not everything should be controlled by the firmware so as to minimize the number of switches; that's short-sighted.)  And in the reviews of any such product there's usually at least one from a customer who forgot to set it, fried an expensive device, and regretted ever buying that particular battery.  I haven't done that so far, but maybe it's only a matter of time ...

So the choice of a lightweight power pack is slightly trickier than it seems.  There are hidden gotchas.

Edited to add: As long as I'm complaining, another point is that a nice convenient digital display to show the % charged seems more attractive than it used to. Otherwise there's some guesswork involved. So I am leaning more toward the XTPower products, and I suggest that anyone who is in the market for one of these things should take a close look at those ... mainly, if you can stand the weight and the cost, the MP-50000. But I don't know yet how the XTPower firmware handles the voltage selection; maybe it has the same misfeature as all the others.

[Fats Drywaller]

The trashy Gissaral pack at supposedly 130 watt-hours is just barely good enough for one night of CPAP use.  I'm getting a time of 7 hours 54 minutes before it shuts down, then a 4-hour full charge using the AC adapter.  I don't know whether the pack's controller is switching off before the cells are drained, but I don't want to damage the thing by doing that routinely, so I'll be looking for higher capacity at the expense of more weight and cost.    (I'll be spending as much in the long run as if I had bought an overpriced BPS or Medistrom 97-Wh "solution" [but not a Resmed Power Station II!] to begin with.  That's OK; I expected that.  It's a hobby expense, basically.)

As I said, the XTPower MP-50000 at 195 Wh for $200 looks excellent on paper for quality, reliability, digital display, and rave reviews.  However, it doesn't have a dedicated 12V output jack, so the voltage selection is done softwarily, therefore it will have the same risk as the Gissaral if it's too stupid to save its settings (which I don't know).  The Poweroak/Maxoak, 162 Wh (?) for $135, which some folks here have been using, is another possibility, and that one has a 12V-only jack.

But for higher capacity at a lower price than the XTPower, I'm looking at eventually getting a Renogy RC-P72000-01 (Az search string "Renogy 72000mAh Portable Charger Generator External Battery Power Bank").  266 Wh, $160, weighing 3.2 pounds as reported by a customer (the seller claims 2.87 pounds).  Can give up to 4A at 12V, so CPAP startup current not a problem.  At least one customer review says it's great for CPAP use, getting two or three nights from a full charge.

I foresee rating that three stars, because it can't be charged from 12V (OK to me but obviously not to a lot of other folks) and for my purposes, with the cables & BPS Resmed-compatible converter I'll be using, it has the voltage-selection misfeature in which everything is controlled by a single button and that setting is not saved.  One good point, though, is that for anyone using the official Resmed #37297 converter rather than the BPS, the Renogy has a cigar-lighter output jack that does only 12V, supposedly 15A (!) max.  That would be the way to go to prevent an accidental machine-frying with overvoltage by forgetting to switch before plugging. (But with the Resmed or BPS converter via the other output jack, presumably one would fry the converter box rather than the machine. Um, OK.)

No digital display; the usual 4 LEDs to show only an approximate charge percentage, and 4 more to show output voltage: 12, 16, 19, or 21.

The Renogy seller on Amazon seems to be blocked by a language barrier from answering customers' questions correctly; among other things, he has repeatedly misunderstood questions about whether it can be charged from a vehicle's cigar-lighter jack, saying yes when the answer is obviously no because the only charging input requires 15VDC.  Apparently he thought the question was whether the device has a cigar-lighter output.

The maximum charging time is not given on the product page or on the minimal instruction sheet from the Renogy web site but is certain to be all day because of the super-high capacity.

[Fats Drywaller]

I just remembered that those Resmed-compatible DC-to-DC converters should accept 12V or 24V as input. (In the case of 24V in, their function is to provide the secret Masonic handshake.) The question is whether they'll take anything in that range or whether they want strictly 12V or 24V. If anyone who has one knows or can check the user's guide for that, please post, thanks. Otherwise I'll find out & post eventually (not soon) about the BPS. If the converter is accommodating enough, then the battery pack's output voltage selection matters a lot less with regard to maybe damaging the equipment (it still matters for maximizing the run time).

That leaves the voltage-selection hazard with non-Resmed machines unless one is using a 12V-only cigar-lighter output.

Now that I think of it, this is also a p.s. to an earlier thread about a 20V output working with the Resmed when the 12V didn't because the battery pack being used was too anemic.

Edited to add:

I got the BPS 24v power converter for Resmed air 10 & s9 series devices. Specs say input:12v dc output: 24v/3.75a max.

Resmed's own converter probably takes anything in the range of 12 through 24.

The manual at https://www.resmed.com/uk/dam/documents/...lo_eng.pdf is not much help; it says "12V/24V DC 13/6.5A".