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[Equipment] Battery Pack for travel
#11
Be sure you can carry whatever battery you get on the airplane or whatever transport you use.

Lithium batteries must be charged with the manufacturer's charger, or fire may result.

There's a lot of snake oil, incomplete information, and convenient omissions of data in battery specs. Many people also misapply the info, even when correct.

Be very careful the battery will power the equipment for long enough. Try it at home first.
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#12
(06-06-2013, 10:55 AM)archangle Wrote: Lithium batteries must be charged with the manufacturer's charger, or fire may result.

Not sure if that applies to the LiFePo batteries, as the Shorai I have in my R1200R is designed to take a charge from the motorcycles alternator, and had been doing so just fine for a year now.

I know that is definitely true for lithium ions cells though.
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#13
(06-06-2013, 02:27 PM)mchad Wrote:
(06-06-2013, 10:55 AM)archangle Wrote: Lithium batteries must be charged with the manufacturer's charger, or fire may result.

Not sure if that applies to the LiFePo batteries, as the Shorai I have in my R1200R is designed to take a charge from the motorcycles alternator, and had been doing so just fine for a year now.

I know that is definitely true for lithium ions cells though.

Good point. Your particular battery is designed to be charged by a standard motorcycle alternator, so it's sort of the same thing. Any lithium battery should be charged by the manufacturer's charger or a type of charger approved by the manufacturer.

I'm not sure whether lithium polymer batteries are generically more tolerant, and how much more tolerant they are. It would be interesting to find out if the one you have has some sort of charging protection circuitry inside the battery case to make it safer.
Get the free SleepyHead software here.
Useful links.
Click here for information on the main alternative to CPAP.
If it's midnight and a DME tells you it's dark outside, go and check it yourself.
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#14
(06-05-2013, 04:00 PM)mchad Wrote: The lithium iron phosphate batteries are freakishly light. I bought one for my motorcycle. 28 amp hours at 3.5lbs. Simply amazing.

Yes they are light, but upon further research, I have found that they are not well suited to this purpose.

28AH "PbEquivalent" will not yield 28 AH of DC current over a sustained draw. I spoke with two of the major manufacturers and they explained that the lithium iron phosphate batteries have much lower internal resistance than lead acid batteries so when they say "28 AH PbEQ" they mean that their much smaller, lighter batteries will put out as much current for a brief period (like for an engine start) as would a 28AH lead acid battery put out for an engine start. The actual capacity is much, much lower for sustained output as one would desire in a CPAP DC battery power source.

Summary:
BOTH MANUFACTURERS TOLD ME "NO" TO USING THESE TO POWER CPAP..............

OMyMyOHellYes
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#15
(06-06-2013, 09:48 PM)OMyMyOHellYes Wrote: Yes they are light, but upon further research, I have found that they are not well suited to this purpose.

A PbEQ lithium battery may not be as well suited to the purpose as a lead acid battery of the same capacity, but that doesn't mean it won't work well. Yes, it will need to be be charged more often, but it has advantages in that it's lighter and more compact.

It probably won't stand up to as many charge cycles, either. But it may be a better option if you have to carry it around, and as long as you've got a solar charger with you it can be used it in places where there's no access to the grid.
Sleepster
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INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.
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#16
(06-06-2013, 10:07 PM)Sleepster Wrote: A PbEQ lithium battery may not be as well suited to the purpose as a lead acid battery of the same capacity,

The problem is, there ARE no Lithium Iron (LiFe) batteries of the same capacit yunless you talk really small SLA batteries (< 10 AH). The "lead equivalent" (PbEQ) AH rating shown on the LiFe batteries are not at all comparable between battery types as a measure of sustained delivery capacity. In fact, the LiFe batteries actually have about one-third the AH capacity of their listed "PbEQ" rating according to the manufacturers.

The manufacturers said that they are engineered as starting batteries - not batteries for a long draw as if they were to be used as a CPAP battery power supply. Note that an 18 AH PbEQ battery - a "true" 6 AH battery - delivers an estimated equivalent cranking current as an 18 AH SLA battery for maybe 5-10 seconds at a shot. Thus their "PbEQ" rating.

So, the 18 AH "PbEQ" LiFe battery would actually be estimated more as a 6 AH equivalent in this kind of application. So - if your CPAP draws a 1 amp load at your pressure, the 18 AH SLA battery would be good to go for 12 hours with a 50% safety margin. The LiFe that costs 6-10 times as much and would be good for maybe 4 hours..... Buy three of them for around $600. You get three LiFe batteries that cumulatively weigh just under 10 lbs as opposed to a single 14 lb SLA battery, at $30, for the same duration power supply.

If you only NEED 4 coverage hours and don't mind spending $200 bucks for that 18 AH PbEQ, then it might start to make sense.

OMyMyOHellYes
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#17
(06-07-2013, 07:16 PM)OMyMyOHellYes Wrote: So, the 18 AH "PbEQ" LiFe battery would actually be estimated more as a 6 AH equivalent in this kind of application. So - if your CPAP draws a 1 amp load at your pressure, the 18 AH SLA battery would be good to go for 12 hours with a 50% safety margin. The LiFe that costs 6-10 times as much and would be good for maybe 4 hours.....

What then are they designed for? Starting a car?!
Sleepster
Apnea Board Moderator
www.ApneaBoard.com


INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.
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#18
(06-07-2013, 09:19 PM)Sleepster Wrote: What then are they designed for? Starting a car?!

Motorcycles, primarily. Maybe four wheelers. Gas golf carts. Small generators. Riding mowers. Mules (the ATV variety, not the plowing ones. But I'm guessing that improperly applied might start the plowing kind too).

Kind of disappointing. I was hoping initially to have found a real solution to portable power.

OMyMyOHellYes
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#19
The bigger the lithium battery, the greater the chance of fire, and the more serious the fire is if it happens. As Boeing found out to their great cost.
Get the free SleepyHead software here.
Useful links.
Click here for information on the main alternative to CPAP.
If it's midnight and a DME tells you it's dark outside, go and check it yourself.
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#20
(05-26-2013, 11:49 PM)OMyMyOHellYes Wrote: Right now, I'm thinking something between 35 and 45 AH capacity, figuring in that 50% safety fudge factor (I am told that I can expect the batteries to really start dropping capacity as they approach the 20 hour mark and that over time on the bench will drop capacity, even with good maintenance.)

Is 35-45 AH for any PAP machine for (3) days run time ?

Would a Marine deep cycle battery and a 400 Watt Inverter do the job ? Obviously not for the OP who needs a lightweigh solution, but would this above setup work ok for a stationary setup that has no electricity (say like a temporary power outage) ?



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