CPAPtalk.com

Seawind36 wrote: ↑

Mon May 28, 2018 9:17 pm

As long as you're not using heated humidifier or heated hose you would probably do well with a few of these U1 scooter batteries. Just remember you don't want to discharge them down to 0% of capacity as it will shorten their life. Plan to use 50-80% of the battery capacity, then charge.

Does this apply to the deep cycle batteries? How do know how far down they are?

That is deep cycle batteries. starter batteries are more like 15-20% of capacity.

Seawind36 wrote: ↑

Mon May 28, 2018 9:17 pm

As long as you're not using heated humidifier or heated hose you would probably do well with a few of these U1 scooter batteries. Just remember you don't want to discharge them down to 0% of capacity as it will shorten their life. Plan to use 50-80% of the battery capacity, then charge.

Does this apply to the deep cycle batteries? How do know how far down they are?

Wow - so much happens while you sleep!

First - scooter batteries are a good choice. The U1 size is 24 pounds for 35 amp-hours. They are deep cycle, which means they can be drained to about 20% around 200 times. If you go to zero that number goes way down. If you only go to 50% you might get 500 to 1000 cycles,which may be important if you're using them daily. Shop around - cost should be about $65. And use the ResMed converter, don't use an inverter.

If you don't use humidity, you might well get 4 nights from one battery. A second is a good backup. (If you use my BatteryTender setup get a second "ring connector" for the second battery for fast changing.) You could also get a larger AGM - it all depends on your settings, wallet, and other needs. If you want humidity, its a different ballgame - you would need a large battery to go 4 nights.

BTW, starting batteries are considered too low to reliably start when depleted only 30% (to 70% State of Charge), and can be permanently damaged by even a single discharge to zero.

chunkyfrog wrote: ↑

Mon May 28, 2018 9:08 pm

I bet CapnLoki has been boating today . . .
And having fun--I hope.
He helps a lot. He deserves a load of fun.

I was having fun on the boat, but its still on land - Launch is set for Friday.

I was installing a new controller for the solar panels, and testing out a new inverter and a charger for my computer. I guess that's a fun day for me!

palerider wrote: ↑

Tue May 29, 2018 12:00 am

lordvader wrote: ↑

Mon May 28, 2018 11:16 pm

Honda is the way to go. Super quiet.

many times more expensive than a battery, and *infinitely* noisier

I agree! And I certainly wouldn't want to run it all night - that's rather anti-social!

I have a Honda for charging when the solar panels fall behind. I recently converted it to propane so I don't have to carry gas on the boat.

amenite wrote: ↑

Mon May 28, 2018 8:16 pm

I guess Toyota Prius owners already know this, but from what I've read the more recent Prius models have inverter + A/C outlets built in (maybe as an option?). If car camping I think I would borrow a Prius if I could get my hands on one. The kicker is the car can be put in what is called "Ready" mode whereby you can plug stuff in and run it off the battery via the car's inverter, and the car just turns on when the battery runs down low enough, charges the battery, then turns the gas engine off automatically. From what I've read this was something you had to hack with older models by tying an inverter in to the standby battery pack in the rear of the vehicle, but Toyota has added this as a feature with the inverter built in and a few a/c outlets.

I'm not sure I'd be happy camping next to a car that might start by itself in the middle of the night! Actually the load of a pump for a few nights shouldn't trigger that. Also, I don't think I would borrow someone's car for a camping trip just to save a few bucks on a battery.

CapnLoki wrote: ↑

Tue May 29, 2018 5:13 am

I'm not sure I'd be happy camping next to a car that might start by itself in the middle of the night! Actually the load of a pump for a few nights shouldn't trigger that. Also, I don't think I would borrow someone's car for a camping trip just to save a few bucks on a battery.

It might work for someone who needs their heat and humidity. Or if you have a few people who need power. And if I can power the home with it in an outage even better.

amenite wrote: ↑

Mon May 28, 2018 8:16 pm

I guess Toyota Prius owners already know this, but from what I've read the more recent Prius models have inverter + A/C outlets built in (maybe as an option?). If car camping I think I would borrow a Prius if I could get my hands on one. The kicker is the car can be put in what is called "Ready" mode whereby you can plug stuff in and run it off the battery via the car's inverter, and the car just turns on when the battery runs down low enough, charges the battery, then turns the gas engine off automatically. From what I've read this was something you had to hack with older models by tying an inverter in to the standby battery pack in the rear of the vehicle, but Toyota has added this as a feature with the inverter built in and a few a/c outlets.

I think there is an option in Japan for the Prius PHV (our Prius Prime) [the current plugin] that permits running something small like a coffee pot on a picnic. This accessory would not work on the US models though.

Many people camp in a Prius with it in READY mode using the air conditioner. The engine only runs periodically to charge the large battery, for about 5 minutes at a time. If you have the 12V adapter for your CPAP that could work.

Most CPAPs that have an external power brick (a piece that looks somewhat like a literal brick in the power cord) run on direct current. I believe that this includes the one you have. The brick accepts alternating current and coverts it to direct current.

Thus, if you're using a battery or a DC generator, it makes no sense to use an inverter that converts it to AC and then use the standard household power cord to convert it back to DC.

Seawind36 wrote: ↑

Mon May 28, 2018 9:17 pm

How do know how far down they are?

Unfortunately, that's a real tough question. I have some expensive instruments to track daily use but it still comes down to experience and guesswork (is there any difference between the two?) The traditional test is a simple voltmeter. Fully charged is 12.7 volts, half is around 12.3. When it goes below 12.0 you may want to charge. If there's a load on the battery it will be somewhat lower, and of course there's a variation between batteries. In fact, if you google "agm voltage state of charge" you'll find a number of charts with variations as high as 0.3 volts.

You can also get a basic cigarette lighter plugin volt meter "fuel gauge." If you do my setup you'll have a cigarette socket, and with the 1 to 5 splitter you could add a second if you want to monitor continuously or charge a cell phone.

Its important that you try out your setup before the trip, but it might be painful to run without humidity for 4 nights to see if the battery lasts! I wish I had a better answer. After your first trip you'll have a much better understanding of how it works for you.

BTW, if we knew your pressure setting and camping location (high desert or swamp, etc) we could make a better guess on the usage.

My pressure is set at 13. I will be camping in the hills of East Tennessee near a river. I found a 40 w solar panel and was thinking maybe I could use that to charge the battery during the day (assuming we have sun!)

amenite wrote: ↑

Tue May 29, 2018 5:24 am

And if I can power the home with it in an outage even better.

Yes, yes, we can clearly see your agenda.

Seawind36 wrote: ↑

Tue May 29, 2018 10:49 am

My pressure is set at 13. I will be camping in the hills of East Tennessee near a river. I found a 40 w solar panel and was thinking maybe I could use that to charge the battery during the day (assuming we have sun!)

So the S9 AutoSet at pressure 13 with no humidity or heated hose draws about 0.75 Amps at 12 volts through the converter. 8 hours is then 6 amp-hours, 4 nights is 24 amp-hours, so a single fully charged U1 battery (with 35 amp-hours) should last with a fair margin.

https://www.resmed.com/us/dam/documents ... lo_eng.pdf

The way to estimate solar panels is take the wattage, divide by about 17 (the voltage of most panels) to get the max amps - about 2.35 amps for your panels. Then you find the solar factor for your location - its about 4 for much of the East in the summer. That is the estimate average total hours assuming you kept the panel in sun all day. That would come to over 9 amp-hours, more than you'd use in a night. Unfortunately, it assumes "average" weather so you could easily have 3 overcast days. Sometimes even seemingly nice days don't have good illumination. Also, if you're on the south side of a hill, or shaded by trees, you might only get partial sun. I get most of my power on the boat from the sun, but my panels are almost never shaded, and I have several fallback options. For these reasons, I usually advise not getting into solar unless its a real long term commitment. For the cost of the panel you could get a second battery which will be more reliable.