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Battery usage, while camping
#31
(05-13-2017, 11:58 PM)justMongo Wrote: The big danger is:  Don't short the terminals.  They can provide tremendous amounts of current.

While prudent to not charge in an enclosed area; a charger that does not exceed the gassing Voltage should not blow the vents open on a SLA/AGM.

remember the old VW Beetles (air cooled), their battery was under the rear seat.  And it was a flooded, vented lead acid.

You should never need to add water to an SLA.  There's no place to add it.

Up to around '67 or '68, those were 6V battries.

And almost universally, there was eventually a rusted out pan under the right rear passenger seat......

In all that has been said, I think the required battery capacity has been vastly overestimated (as you pointed out).  Especially as the user says they can recharge daily. I would hate the thought of having to schlep around a 105 AH battery.......  Lordy.  I think I could get a solid two-three weeks out of a 105 AH battry before requiring recharge. I would bet a 20 AH battry would be more than sufficient for a single night. A 35 AH would certainly seem more than adequate and still manageable.

OMMOHY
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#32
I agree with the 35 A-hr. And, I'd use the Deltran 12V, 5 amp Battery Tender to charge it.
That 35 A-Hr battery is heavy enough.

And, we HAM radio people usually keep a battery in our shack -- which might even be in a bedroom

I'm not even sure you can get a battery in the 100 A-Hr range -- unless it's industrial.
My big V8 Mercury uses a 55 A-Hr battery.

Remember when car batteries were under the driver's floorboard? The master cylinder for the brakes usually wasn't too far from it.
BBQ de ARZ K
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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#33
(05-14-2017, 10:35 AM)justMongo Wrote: I'm not even sure you can get a battery in the 100 A-Hr range -- unless it's industrial.
My big V8 Mercury uses a 55 A-Hr battery.
Oh, I just googleated and the first return was for a Lifeline 105 AH AGM battery - list price was $520 on sale for about $320.  Weight was around 70#. 

WAY to big and heavy.  WAY WAY too expensive.  Kind of like getting a Peterbuilt tractor to tow a small Airstream trailer for that camping trip.

OMMOHY
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#34
(05-14-2017, 10:35 AM)justMongo Wrote: I agree with the 35 A-hr.  And, I'd use the Deltran 12V, 5 amp Battery Tender to charge it.
That 35 A-Hr battery is heavy enough.

I don't understand how this conclusion is reached.

The power supply uses a maximum of 6.67 amps @ 12v

The OP has said he uses near maximum pressure of his machine and humidification.

What is unknown is how high a level of humidification is used. Obviously the higher the setting, the higher the power consumtion.

It would seem to me that an average current draw of 5 amps & 12v (60w) is easily possible (& potentially higher).

Assuming 5amps - & 7 hours per night  - that is 35 Ah nightly usage. Discharging a 35Ah battery to that extent each night will undoubtedly result in very short battery life.   At the minimum a 70 Ah battery would be needed to ensure an economical lifespan.   

A 105 AH battery would provide an extra night without charging which may or may not be desirable. If charged to 100% (float) daily a lifetime of 10 years would be a reasonable expectation. However the 'cost' is the additinal weight of the battery. If charging to full every day then 70Ah would be a good compromise, with less weight & a still reasonable lifespan.

The 5 am Deltran multi stage charger looks like a reasonable option provided the OP has access to mains power whilst camping. If relying upon solar or vehicle based dc to dc charging the required 7 hours of charging to replenish what has been used overnight would be impractical & a higher output solar regulator or dc to dc charger may be needed.  Same if relying on a generator to provide the charging power unless the OP is happy to live next to a generator running all day whilst camping.

If the nights are chilly, condensation is a greater possibility inside the tent, & if a heated hose were used to counteract this then nightly power consumption could easily rise to double what I have suggested. I know folk who regularly use 60+ Ah with their machines each night in their motorhomes because they use a heated hose.
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#35
(05-14-2017, 05:11 PM)Cuppa Wrote:
(05-14-2017, 10:35 AM)justMongo Wrote: I agree with the 35 A-hr.  And, I'd use the Deltran 12V, 5 amp Battery Tender to charge it.
That 35 A-Hr battery is heavy enough.

I don't understand how this conclusion is reached.

The power supply uses a maximum of 6.67 amps @ 12v

The OP has said he uses near maximum pressure of his machine and humidification.

What is unknown is how high a level of humidification is used. Obviously the higher the setting, the higher the power consumtion.

It would seem to me that an average current draw of 5 amps & 12v (60w) is easily possible (& potentially higher).

Assuming 5amps - & 7 hours per night  - that is 35 Ah nightly usage. Discharging a 35Ah battery to that extent each night will undoubtedly result in very short battery life.   At the minimum a 70 Ah battery would be needed to ensure an economical lifespan.   

You are approaching the analysis by saying "this is what the power supply provided by the manufacturer will do at max output" and assume that the machine actually USES that much power.  Don't do that.  The machines don't use that much.  Not even close.  

You need to know how much the machine ACTUALLY uses.  ResMed puts out tables that tell you how much battery you need for a night's use.  Their estimates actually are stated at 150% of what is really needed as a safety cushion.  Respironics is more cagey and will not publish that kind of data, so I am going to reference the ResMed tables for this exercise (I actually measured the current draw on my Respiroincs units to size my emergency batteries (get 4-5 nights with 50% safety factor, up to 7 if I could get the full 35 AH out of them)).

So, when running off a battery, do not, under any circumstances, use a heated climateline tube.  Or if you do, make sure it is turned OFF.  The heated tube is NOT even a "comfort" feature.  Its only purpose is to prevent condensation in the tube.  And if one is getting condensation, the RH in the air their machine is putting out is probably too high anyway.  Turn down the humidifier temp. Or get on e of them flannel tube cozies.

Also, in my rulebook, it says when you are on batteries, do not do heated humidification.  If you MUST have humidification (and IMO many people that think they do really don't - they used it because it came with the machine) use passive humidification.  Without humidification, a PAP wearer will be getting the same RH to their sinuses as everybody else that is not using PAP and they are typically not missing additional humidity. 

These two things will REALLY conserve battery power.  But for sake of this discussion, we will assume use of some heated humidification.

Per the ResMed Battery Guide the S9 VPAP Auto at a setting of 25 with the humidification set in the middle at "3", the current draw is 2.26 A per their table.  8 hrs at that draw would require 18 AH.  Throw in a 50% safety cushion and you get to about 28 AH.  For a 7 hour night, current draw would be 16 AH - battery with safety would be 24 AH.

Without ANY heated humidification (and I bet they could do that) the current draw drops to 1 A at a pressure setting of 25.  The 8 hour nightly draw would total 8 AH - an 12 AH would be more than enough to power a whole night with a 50% safety cushion.  For a 7 hour night, a 7 AH draw results, with a 12 AH battery providing more than 50% reserve.

So, comparing a 105 AH battery to a 35 AH battery, you get $62 vs $320 from a cost standpoint.  You get 23# vs almost 70# from a weight standpoint.  45# of unneeded weight is a metric buttload.

My results for the Respironics 560 compared to the ResMed S-9 are slightly worse, but not materially.  I know this is comparing machines that are one generation behind, but that is the best data i gots.   But I think the analysis is pretty close to reality as opposed to basing current draw estimates on the capability of the manufacturer's power supply.

And as far as running the batteries to the point where the CPAPs fall offline due to low voltage, yes, theoretically you will shorten their life, but in a real sense, doing it a few times will not appreciably shorten their life.  Yes, if you ran them EVERY NIGHT you might see a noticeable fall off.  But if they are occasional use batteries, you are not going to see any diminution of life cycle.  You are going to have to replace them at 5-7 years regardless of how well they are used and maintained, just because they are going to kill themselves anyway without any outside interference.  I maintain two 39 AH batteries and one 35 AH battery at home for emergencies and I can go indefinitely on those for APAP, limited lights and radio use.  I can charge off of a 140 W solar panel off grid.  I have only occasionally used the batteries, maybe once every couple of years due to emergency and I may pull them out annually or maybe twice annually to exercise them.  So they are pretty much a sunk cost anyhow.  And yes, I have tested them by running my APAP (no heat) off of them for at least a week solid and did not get to the point where they were depleted (IIRC, I assumed 11.7 V as a dead battery.)

And by the way, that Candygram feller up above, IIRC, am a EE perfessionally.  Or at least in a related engineering field.  And knows his shi, er, stuff.

OMMOHY
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#36
Following the assumption that a Resmed & Respironics machine are comparable power comsumtion-wise
From the Resmed S10 Autoset manual:

Max power consumption 104w = 8.667 amps @12v
Typical power consumption - 53w = 4.417 amps @ 12v

I would think that running at a pressure of 24 +humidification would constitute higher than 'typical'.
Thus the 5 amps I previously suggested (clearly less than the maximum the power supply can provide) is in the ball park.

If running any appliance until it stops running due to low voltage you are into battery killing territory. I am more familiar with low voltage cut outs on portable compressor fridge freezers, These are commonly set at 11.8v or below. Fridge manufacturers frequently refer to this as 'battery protection', which is nonsense, but helps to maintain fridge sales. In reality the low voltage cut out is appliance protection. Very different.

The OP may well be able to manage with less, or even no humidification, & if so would use way less power, but that is not what he asked about.

I believe you are taking a valid view of using a smaller battery, trading off initial cost & weight, for a shorter battery life. No problem with this provided that it is understood as a trade off.

Your point about 'Occasional Usage' is a good one. I am used to using batteries as a full time power source & thus come to the discussion from that perspective.

The best advice offered to the OP has been to hook up his machine to a battery to check the actual consumption of his machine used as he prefers. I would hope that a decent battery supplier would be able to do this if the OP doesn't have a means of monitoring the current used at home. Once he knows for sure what it is using he then has sufficient information within this thread to decide how he wishes to use whatever battery he purchases.
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#37
(05-14-2017, 10:28 PM)Cuppa Wrote: The best advice offered to the OP has been to hook up his machine to a battery to check the actual consumption of his machine used as he prefers.

Yes, measure the current. Anyone who wishes to get into battery operation should be able to make these measurements.
Buy a DVM. You can always build a box with two analog meters, Voltage and Current as part of your battery solution.
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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#38
The weight is obviously a factor, but this isn't any kind of back woods camping, so I won't need to move it far.  Also, I can plug it in to a charger daily, plugged into a standard outlet, so I'm not worried about a lack of juice, during charging.

For the price, the one that I had looked at, was a 105AH Duracell, from Batteriesplus, for $120.  It sounds like everyone agrees, that I can use a lower AH, just how much lower is the argument.

The way I understand the last few posts, is that I should be able to bring my machine into a battery dealer, and they can measure the consumption of the machine, with me turning it on?  I'd assume with me breathing in and out of the mask too, since it is a BiPAP?

Thanks again for all of the advice.
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#39
(05-16-2017, 03:58 AM)hansk Wrote: The way I understand the last few posts, is that I should be able to bring my machine into a battery dealer, and they can measure the consumption of the machine, with me turning it on?  I'd assume with me breathing in and out of the mask too, since it is a BiPAP?

I suggest you set up at home and make that measurement. Most people who have come up with their own battery solutions have the basic equipment to make such measurements. And, yes, it needs to be under load, the way you'll be using it -- or the measurement will not represent your use.


( if you do take it in to a battery dealer -- would you bring along a second person as a photographer. We'd love to see some photos! Cool )

Eat-popcorn
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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#40
(05-16-2017, 08:08 AM)justMongo Wrote: ( if you do take it in to a battery dealer -- would you bring along a second person as a photographer.  We'd love to see some photos!  Cool )

Eat-popcorn

Haha I'm sure that would be quite the sight haha.

Forgive my ignorance, as I'm not exactly savvy with this stuff, but what would I need/what tools do I need to measure this? How do I go about doing it, with said tools?

I know, from my original post, that I can't post the link to another unapproved site, for the battery that I'm looking at, but I was original looking at the 100 AH Duracell from Batteriesplus, for under $120. They also have other brands, and have lower AH Duracell's (90 & 75). They are all deep cycle. Do they sound like reasonable batteries, or is there a better brand to look for?

Thanks again!
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