Need advice from those with camping battery experience...

[rogerconnelly]

Hi everyone,
I have read all the wonderful advice in other posts (and there are many!) on how to put together a proper battery for camping - and I will take that advice in the future - but this week I got an opportunity to go on a last minute camping trip to Pismo Beach - so in a minute of desperation I bought one of these...

http://www.amazon.com/Stanley-DPS109-Di ... B001U0FDAQ

Which doesn't seem to work with my cpap machine - even if I remove the humidifier (as I have seen advised to consumer less power). The block on my power chord says it's 12V, but maybe I have to get an inverter and plug into the DC out on this little batter pack? If I plug into the AC, my cpap unit doesn't even come on. Please advise.

I had two days left so I ordered the slightly more powerful (and most importantly with the longer 28 amp hour rating - as opposed to the above unit which only had a 9 ah rating)...

http://www.amazon.com/Duracell-DPP-600H ... sbs_auto_1

Do folks think I'll have better luck plugging into this unit once I get it (the day before my trip this Friday I hope)? My only other alternative is plug into my trucks battery, which didn't sound recommended - or I sleep in a hotel while others are in the fun tents - or I go without my cpap (which I really don't want to do).

- help! -

[moresleep]

Either of those should work, if you connect a cord from cigarette-lighter-socket on the jump starter to the 12v input on your machine. Your PRS1 Bipap seems to have a 12v input, at least according to Cpap.com:

"This machine come equipped with a DC plug on the back of the unit. This allows the user to connect the CPAP to an external DC battery source. The machine can be powered by plugging the 12volt DC Power Cord into a cigarette lighter plug. This is ideal for traveling by car, boat, or recreational vehicle that is equipped with a cigarette lighter plug. "

Perhaps someone here who has your machine can tell you exactly how to connect it to the jump starter. Otherwise, if it were me, I would take the Bipap to a Radio Shack and get someone there to help me select a cigarette-lighter-plug cord with the proper tip for connecting to your machine. Cpap.com might be able to overnight you the cord, but Radio Shack may have something in stock that would work.

Good luck!

[rested gal]

I have read all the wonderful advice in other posts (and there are many!) on how to put together a proper battery for camping

For new readers who want to find those "many other posts" Roger mentioned ...

LINKS to Battery operation, camping, power outage
viewtopic.php?t=9682

[GumbyCT]

1st I have no idea what Pismo Beach is so I am not as excited as you.

Either of those jump starters should work but generally speaking the larger AH (Amp Hours) the more blower time you should get.

You must be doing something wrong if the machine won't power on but from the clues provided I can't even offer a suggestion, sorry.

[LinkC]

1. Forget about any scheme involving an inverter. Your machine (without humidifier) uses 12v DC. Period. Taking a 12v battery, inverting that to 120vAC, THEN using your plug-in-the-wall power supply to bring it BACK to 12vdc is insane. Much of your battery's capacity will be wasted as loss (heat) in the double conversion.

2. Use an appropriate cord to go directly from a 12vdc "jump starter" portable battery to your machine's 12vdc power input. All you need to worry about is a. does the plug fit the machine input; and b. is the polarity correct.

The math is straightforward. Look for the battery's capacity in Amp-Hours (NOT the x00 Amp rating plastered all over the front. That is meaningless for our purposes.) Mine is 32aH. My M-series draws a peak 3 amps. 32/3 = just under 11 hours. Factor in loss and manufacturer exaggeration and I can expect to get about 8-9 hrs on a charge. Maybe more as my machine won't draw "peak" all the time.

[Vader]

This has got to be one of the most commonly asked questions here,(camping with cpap) but I'll be danged if there's been a definitive answer...in "laymens terms".

I would *guess* the Duracell battery backup would work (but I've never tried, because I have a whole house generator) for your machine. Seeing that there is a normal grounded a/c input connecter, I wouldn't think it would require a special 12v dc adaptor either.
Perhaps someone else here can tell you if they have actually tried the Duracell that you have, or a similar unit. Going through all those links is no easy task, not to mention confusing. But I wouldn't mind knowing this myself, in case I decide to go camping at Pismo Beach!

[rogerconnelly]

Thanks everyone - I really do appreciate it!

LinkC, how do I find out that "peak amp draw" number for my machine so I know what to divide by? Anyone know this number for the System One?

[davelikesbeer]

The first time I used my battery for camping, I blew a fuse. Unfortunately, I didn't have spare fuses so I didn't sleep too well. Check your fuse, especially if you plugged it in with the humidifier attached.

The fuse is in the part that plugs into the 12VDC outlet (cigarette lighter).

Dave.

[archangle]

Thanks everyone - I really do appreciate it!

LinkC, how do I find out that "peak amp draw" number for my machine so I know what to divide by? Anyone know this number for the System One?

The power supply says 5 Amps output, so the machine should draw less than that. That includes both the blower and the humidifier.

I measured the AC power draw overnight and got around 20 watts average over a night's usage, if I remember right. I'll have to run it again and double check. That would be less than 2 Amps draw on DC.

Current load probably varies with pressure, humidifier settings, etc. I'm around 12 cmH20, low humidity setting, so your current may vary.

[LinkC]

Owner's manual. Or a specifications label on the machine itself.

5.0A does sound like it includes the humidifier, as Arch suggested. I found a manual online for the Sys One PLUS that also says 5.0. But remember that's peak and likely with humidifier. Yes, the draw will vary with settings/load on the machine.

If you can't find a better number, I'd assume it's 3 amps, for battery estimating purposes. Better to be on the conservative side than to run out of juice in the wee hours.

[physicsbob]

One more thing to check is the DC power cable to the cpap. if you are using a cable that was made for a CD player or other device, the wires in the cable might not be large enough to carry the current. I have tried a few where the outside of the cable looked heavy enough, but the wire inside was very small and wouldn't power a cpap. I would recommend either making your own from parts, using at least 18 gauge copper wire, or get the Respronics cable Item #1001956 from our sponsor.

[rogerconnelly]

I was in to see my DME this morning (separate issue - just changing to a new mask) and asked her if they had the DC cable for my machine - which they did - although for a lot more then I would have paid for on our host site - but at least I have it in hand now as I leave tomorrow morning for my camping trip. One more lesson for me on not planning ahead better But, wish me luck on this, my first cpap camping excursion - I'll report back on how it goes

[Mr Bill]

Good luck and looking forward to hearing how it went.

[GumbyCT]

I was in to see my DME this morning (separate issue - just changing to a new mask) and asked her if they had the DC cable for my machine - which they did - although for a lot more then I would have paid for on our host site - but at least I have it in hand now as I leave tomorrow morning for my camping trip. One more lesson for me on not planning ahead better But, wish me luck on this, my first cpap camping excursion - I'll report back on how it goes

That begs the question - what the hey did you use for a cable the first time?

[archangle]

I was in to see my DME this morning (separate issue - just changing to a new mask) and asked her if they had the DC cable for my machine - which they did - although for a lot more then I would have paid for on our host site -

Mind telling us how badly you got screwed by the DME?

And what DID you use to connect it the first time?