XPAP to go?

[ekubaskie]

I saw this in an email from iGet.it today. It looks like a nice combination, and unless I'm off in my electro-math, just about right for running with passive mode on the humidifier, maybe even getting a couple 10-hour nights on a charge. It can recharge from an outlet or in 10-20 hours using the included solar cells - faster if you tack on additional cells. Anybody out there see any mismatch with the needs of a typical hosehead other than perhaps carry weight and size? I also like that it isn't a unitasker; it can be used to power pretty much any electric device in its power/consumption range.

http://iget.it/us/en/details/1188/Goal_ ... nture_Kit/

[gbuskirk]

Your link required registration. I googled the same kit from the manufacturer at this address:
http://www.goalzero.com/shop/p/60/Escap ... enture-Kit

[ekubaskie]

I wondered if that would happen, but since I'm me, the link worked every time, lol. Thanx!

[DreamDiver]

I wondered if that would happen, but since I'm me, the link worked every time, lol. Thanx!

The goal zero apparently has two options for a 12V cigarette lighter adapter depending on the model you buy. You can get that and the PRS1 12V cigarette-lighter to cpap adapter. This would give you the most optimum efficiency for about 2 nights if your heat-disabled humidifier and cpap machine draw less than 10 amp-hours per night.

Yeah, you probably already know, but just in case others don't, it will be less efficient if you use the AC plug into the goal zero.

[CapnLoki]

OK, I'll try the electro-math. I don't know how much power your PR unit uses, but the ResMed loads are outlined here:

http://www.resmed.com/assets/documents/ ... lo_eng.pdf

As a first cut you might figure about 1 Amp load without a heated humidifier, or 8 AmpHours for a "standard night," with some setups as low as 5 AH, but others up to 15 AH. The described unit has a 14 AH AGM battery that claims a life-span of "hundreds of cycles." However, the common wisdom is that AGM batteries will only achieve good life-spans if discharged less then 50% of the total capacity, or for this battery about 7 AHs. AGMs have many virtues, but very deep discharge is not one of them, so if this is fully drained I wouldn't be surprised if it died within a dozen cycles and even a few such cycles could noticeably affect performance. Following this logic, this unit is good for a one night run only if your usage is not very demanding.

I have to assume that the wall and 12V charging times are reasonable, but remember that the last 10% charge usually takes an extended trickle charge, so the stated times may in practice only get you to 90%. The Solar charge time seem very optimistic. The 10 hour time assumes a full 15 watt output or about 1 Amp. On my boat I have 150 Watts of solar panels, but they (at the very best) only put out about 6 Amps; usually I'm happy to see 4 Amps during the middle of a sunny day, and that's taking care that they don't get shaded as the Sun moves in the sky. This means that getting 8 AHs might be possible in perfect conditions, but I would't count on more than 3-4 AHs unless you live in the dessert. A thin overcast would knock that down, and thick cloud cover or rain would almost eliminate solar capability.

On the plus side, this looks like a slick setup that would keep a variety of small devices (cell phone, ipods, kindles, etc) going, with the option of solar charging, if its sunny. But running a xPAP would would be marginal unless its a very low power setup. For one night in a pinch it might work but for longer periods or frequent use I'd be leery.

I'm new to CPAPs, but I've spent a lot of time living on battery power on a boat - most summers plus a few extended periods. The primary load is a small refrigerator, plus lights, computers, boat electronics, a TV, and now a CPAP. My battery bank is sized at about 4 times the daily usage, so that I'm often running between about 60% to 85% charge. This keeps the batteries healthy and gives me some reserve. If it goes below 50%, the voltage drops enough that some devices don't work properly and we go into panic mode!

If I were setting up for home emergency use (I guess I should, now that I'm getting dependent on a CPAP), or "camping" next to a car, I would get small AGM deep cycle battery, about 50 AmpHours for about $100 if you look for discounts. You could go smaller, but make sure you have at least double the expected daily usage. For home use its probably more cost effective to go larger and know that you have a week of runtime, plus power for cell phones, etc. AGMs can be run upside down, so you don't have to worry about it rolling over in the trunk. Gel batteries can also be used, but flooded car batteries have too many issues for portable or even home usage. You can get a good charger for under $50, make sure it has "AGM" mode; and a high quality trickle charger (search "Battery Tender") that you can trust for long term usage for under $40. Proper charging takes computer control that varies the current and voltage according to a formula for the battery type. Look for "3-step" or "4-step" chargers. Don't use a cheap charger or a car alternator for charging an AGM or Gel; this will lead to early death. One virtue of AGM is that it will hold a charge for extended times, much longer than flooded, but for emergency usage you want a good trickle.

BTW, when doing the math remember that charging has a 10-20% overhead in the AmpHours, plus it requires a higher Voltage. Also, avoid inverters which can cost 20%; my PRS1 works fine with a DC cable.

I hope this helps.