Please help me figure out this camping battery stuff

I know there are a ton of threads just like this one. I've read most, if not all, of them and I just feel more confused than ever. I know many of you have extensively researched this and will have valuable insight so I'm begging you to please be patient with another thread asking about battery options and help a fellow apniac out.

My extended family is planning a camping trip for this summer and I'm trying to figure out the best battery option. Here is all the information that's pertinent.

Equipment:
PRS1 50 series Auto. 14-17 range pressure
Humidifier (plan to not activate during camping due to power drain)
I will probably buy this car socket cord unless you have a different reccomendation: https://www.cpap.com/productpage/respir ... -cord.html

Needs/situation
Hoping to be able to get 2 to 3 nights on a single charge
Battery can be very heavy, it won't be carried far from our vehicle.
Ability to charge from car socket or outlet plug is a plus (but not required)
Looking for the cheapest solution that will work for the above.

My initial camping attempt years ago involved using one of those car jumper boxes with a cigarette adapter (straight 12v to the machine) It was an older machine, not my current set up. Anyway, the battery died on me in the middle of the night and I had an awful time. I've avoided camping ever since.

Anyway, my initial thoughts were just to get a car battery and connect directly to that. But based on what I have read, the deep discharges of the steady continuous use harms the batteries health because its not what cars typically do to them. It sounds like "deep cycle" or "Marine" batteries might be the best / cheapest option for a reliable solution? Does that sound right?

So, I guess what I'm looking for is suggestions for the following:
Best / cheapest battery for the 2 to 3 night capacity that can handle multiple charge/discharge cycles. (weight is not an issue up to 50-60 pounds)
Best way to charge it (equipment, process etc)
Best way to connect it to my machine.
Also, any other suggestions or wisdom you could pass my way would be very appreciated.

this thread has the latest
viewtopic.php?f=1&t=103170&st=0&sk=t&sd=a&hilit=camping

Plan to try it out ahead of time because the shipped product has a high failure rate (replacements seem to usually work)

blakepro wrote:...
Needs/situation
Hoping to be able to get 2 to 3 nights on a single charge
Battery can be very heavy, it won't be carried far from our vehicle.
Ability to charge from car socket or outlet plug is a plus (but not required)
Looking for the cheapest solution that will work for the above.

Based on your needs I would recommend the setup I put together recently:

viewtopic.php?t=102775

The battery is 35 Amp-hours, although you probably shouldn't take it below 20%; keeping above 50% gives it hundreds of cycles. My 560 at pressure 9 only used 4 Amp-hours, so you might be around 8 AH per night. In other words, two nights would work, three might be problematical. There are a few easy solutions: get a second battery and use it separately or wired in parallel (NOT in series!), get a larger battery (AGM is preferred but a Walmart 100 AH marine deep cycle is the most bang for the buck as long as you don't have to carry more than 5 feet and you don't tip it over!), or you could spend some time charging from the car since these batteries (Any AGM or flooded deep cycle) are compatible with the car's alternator/regulator and will recover a sizable charge in about an hour. I can figure out the best way to hook this up - be careful with the jumper cables that come with the BatteryTender - they are wired to charge the car battery and may be backwards for your application - I will have to cogitate on this!

I would not recommend the Powered 32000 mentioned in recent threads because it is only about 8-10 AmpHours and would only last you one night, and it takes several hours (maybe 5-6 ?) to recharge from a deep discharge. Also, the AGM batteries I describe are good for home backup and are able to jump start a car and run small aplliances. And the BatteryTender charger is good for slow charging car/motor cycle batteries, etc.

BlackSpinner wrote:this thread has the latest
viewtopic.php?f=1&t=103170&st=0&sk=t&sd=a&hilit=camping

Plan to try it out ahead of time because the shipped product has a high failure rate (replacements seem to usually work)

Thanks for that link. I read all 113 posts. That option looks interesting, but I'm afraid my higher pressure may be a barrier. I'll keep it in mind though. I like how compact and simple it is.

CapnLoki wrote: Based on your needs I would recommend the setup I put together recently:

viewtopic.php?t=102775

The battery is 35 Amp-hours, although you probably shouldn't take it below 20%; keeping above 50% gives it hundreds of cycles. My 560 at pressure 9 only used 4 Amp-hours, so you might be around 8 AH per night. In other words, two nights would work, three might be problematical. There are a few easy solutions: get a second battery and use it separately or wired in parallel (NOT in series!), get a larger battery (AGM is preferred but a Walmart 100 AH marine deep cycle is the most bang for the buck as long as you don't have to carry more than 5 feet and you don't tip it over!), or you could spend some time charging from the car since these batteries (Any AGM or flooded deep cycle) are compatible with the car's alternator/regulator and will recover a sizable charge in about an hour. I can figure out the best way to hook this up - be careful with the jumper cables that come with the BatteryTender - they are wired to charge the car battery and may be backwards for your application - I will have to cogitate on this!

I would not recommend the Powered 32000 mentioned in recent threads because it is only about 8-10 AmpHours and would only last you one night, and it takes several hours (maybe 5-6 ?) to recharge from a deep discharge. Also, the AGM batteries I describe are good for home backup and are able to jump start a car and run small aplliances. And the BatteryTender charger is good for slow charging car/motor cycle batteries, etc.

I read both of your threads and I really like your set-up you have here.

A few questions for you:
If I wanted to skip the battery box but still make things safer, could I connect the quick connect wires that come from the battery tender and then just cover the terminals with hot glue gun to insulate them? I *think* it would protect the setup from any shorts/sparks and In an emergency, I could always just pry off the "glue".

Is there any sort of way to charge this thing while driving somewhere? Like if I connected it in parallel to my cigarette adapter, would it slowly add to the charge? Or would I be at risk of damaging things by doing this?

blakepro wrote:...
A few questions for you:
If I wanted to skip the battery box but still make things safer, could I connect the quick connect wires that come from the battery tender and then just cover the terminals with hot glue gun to insulate them? I *think* it would protect the setup from any shorts/sparks and In an emergency, I could always just pry off the "glue".

I have a thing about boxes because I've seen (several times!) meltdowns from shorted terminals. At the very least get some of those rubber "hoods" that cover the terminals so that an errant screwdriver (or metal lunchbox, etc.) won't cause a disaster.

blakepro wrote: Is there any sort of way to charge this thing while driving somewhere? Like if I connected it in parallel to my cigarette adapter, would it slowly add to the charge? Or would I be at risk of damaging things by doing this?

Your cigarette lighter should have the alternator output (about 14.4 Volts when driving above idle) which is appropriate for charging AGM or flooded batteries. An advantage of larger batteries is that they accept a charge faster - you can figure about it will accept in Amps about a quarter of the Amp-hour rating, so the 35 AH battery I use would accept about 9 Amps from your alternator (which is probably rated at somewhere between 35 and 60 Amps output). It likely doesn't put out enough Volts at idle so you have to be driving to do this. And also, I'll have to look carefully at the wiring so we don't get it backwards, but yes, this is very doable and its all with "of the shelf" parts.

EDIT: It occurs to me that the cigarette lighter might be fused at 10 Amps so you should definitely try this out with a depleted battery before going in the wild. And there's nothing wrong with adding a wire directly to the car battery and running it to your deep cycle battery.

CapnLoki wrote: Your cigarette lighter should have the alternator output (about 14.4 Volts when driving above idle) which is appropriate for charging AGM or flooded batteries. An advantage of larger batteries is that they accept a charge faster - you can figure about it will accept in Amps about a quarter of the Amp-hour rating, so the 35 AH battery I use would accept about 9 Amps from your alternator (which is probably rated at somewhere between 35 and 60 Amps output). It likely doesn't put out enough Volts at idle so you have to be driving to do this. And also, I'll have to look carefully at the wiring so we don't get it backwards, but yes, this is very doable and its all with "of the shelf" parts.

EDIT: It occurs to me that the cigarette lighter might be fused at 10 Amps so you should definitely try this out with a depleted battery before going in the wild. And there's nothing wrong with adding a wire directly to the car battery and running it to your deep cycle battery.

Would that be a male to male cigarette adapter like this: http://www.amazon.com/SOLAR-ESA1-Male-O ... er+adapter
I could plug that directly into the female plug adapter for the battery tender setup: http://www.amazon.com/gp/product/B0041C ... PDKIKX0DER

What would be the best way to check the current charge level of the battery when I'm out camping? Could I just use my little harbor freight multimeter? http://www.harborfreight.com/7-function ... 98025.html

blakepro wrote: Would that be a male to male cigarette adapter like this: http://www.amazon.com/SOLAR-ESA1-Male-O ... er+adapter
I could plug that directly into the female plug adapter for the battery tender setup: http://www.amazon.com/gp/product/B0041C ... PDKIKX0DER

Yes, that should work. I would double check that the positive tip connects to the other positive tip, but its very likely that's the case,

blakepro wrote: What would be the best way to check the current charge level of the battery when I'm out camping? Could I just use my little harbor freight multimeter? http://www.harborfreight.com/7-function ... 98025.html

That's a little problematical. Reading the voltage can give you a rough idea, but there are uncertainties that almost equal the voltage range. You can find simple "battery charge" meters but all they do is is say 12.6 volts is full, and 11.5 is discharged. The problem is these are only remotely accurate when the battery is under a constant load. The best way is an "amp-hour meter," and finding a reasonably priced meter (about $50) was what started me on this. Without that, the best you can do is read the voltage just after running the pump and try to build a "map" of voltage vrs charge.

I use my cpap on whitewater rafting trips all the time. Here is my set-up.....
PR System One 60 Auto A-Flex, No humidifier used while camping
Pressure 15/17
PR shielded DC cord
PR 12V battery adapter cable with clips
Werker 12V 20A batteries - sealed AGM battery

Make sure you buy the PR brand cables. They work best with the PR machine, and are the recommended cables for that machine. I carry multiple batteries when I am off the grid for 7-8 days. The 12V 20A was the smallest and lightest I could find @ 13 lb. each. If you are car camping, you could get a larger battery. I used this system all last summer with wonderful results. I used it as low as the low 30s without any problems. I got 2-3 nights per battery. I was careful not to drain any of the batteries. I carry a smaller battery tester to monitor them. I recharge once I'm home, so I haven't tried to recharge off a car battery. I have a friend who took this same system on a 21 day Grand canyon trip and used a large solar panel to recharge, he felt that the solar recharge option wasn't worth the money or hassle.

I am now in search of a small, light weight battery system for kayak touring. 52 lb. of 12V batteries are no problem to carry in my raft, but not usable in my kayak. Because of my higher pressure settings, the BPS C-100 and the PowerAdd Pilot would probably only give me 1-1.5 nights @ a rather high price. The PowerAdd Pilot is half the cost, but still not great for only one night (plus the mixed reviews on it's function).

For car camping, you will have no problems with a 12V battery set-up. Just remember to keep the batteries charged up at home when not in use. I top mine off every 2-3 weeks to keep them fresh.

raftergirl wrote:I use my cpap on whitewater rafting trips all the time. Here is my set-up.....
PR System One 60 Auto A-Flex, No humidifier used while camping
Pressure 15/17
PR shielded DC cord
PR 12V battery adapter cable with clips
Werker 12V 20A batteries - sealed AGM battery

Make sure you buy the PR brand cables. They work best with the PR machine, and are the recommended cables for that machine. I carry multiple batteries when I am off the grid for 7-8 days. The 12V 20A was the smallest and lightest I could find @ 13 lb. each. If you are car camping, you could get a larger battery. I used this system all last summer with wonderful results. I used it as low as the low 30s without any problems. I got 2-3 nights per battery. I was careful not to drain any of the batteries. I carry a smaller battery tester to monitor them. I recharge once I'm home, so I haven't tried to recharge off a car battery. I have a friend who took this same system on a 21 day Grand canyon trip and used a large solar panel to recharge, he felt that the solar recharge option wasn't worth the money or hassle.

I am now in search of a small, light weight battery system for kayak touring. 52 lb. of 12V batteries are no problem to carry in my raft, but not usable in my kayak. Because of my higher pressure settings, the BPS C-100 and the PowerAdd Pilot would probably only give me 1-1.5 nights @ a rather high price. The PowerAdd Pilot is half the cost, but still not great for only one night (plus the mixed reviews on it's function).

For car camping, you will have no problems with a 12V battery set-up. Just remember to keep the batteries charged up at home when not in use. I top mine off every 2-3 weeks to keep them fresh.

Thank you so much for responding. It makes sense that you would use smaller batteries in multiples for your custom situations. What do you use to test the batteries? Its one of the things I'm concerned with.

Here is my camping setup.

Optima Yellow Top deep cycle car battery out of my old Mercedes (play car).
Home made cable with clips to directly clip on the battery terminals.
Resmed series M Auto with broken humidifier (does not heat up).

I have gotten 5 nights out of the Optima Yellow top and still had plenty of charge left using my ResMed Series M at pressure of 7 with the humidifier turned off.

When I get home from camping the Optima Yellow top battery goes back in the trunk of the Mercedes (where the battery compartment is) and I hookup the car battery cables and trickle charger. It is ready to go for the next camping trip or to start the car after about a day or so.

I specify the Optima because it is a sealed battery that will not spill. The yellow top version is rated for use as a starting battery or a deep cycle battery. The Optima batteries are not cheap ($175?) and not the highest amp hour battery available but it does a very nice double duty job. Once I even used it to jump start the RV!

I have used this in a tent several times but use the exact same setup in an RV even though the RV has its own "house" battery. I always fill the humidifier even though it does not heat up. The passive humidification helps quite a bit.

I use a simple battery tester that I got at Home Depot. It gives me an idea (green, yellow, red) of where I'm at. You can get fancier ones that will give you a more pinpoint reading, but for about $10 I just want a ballpark idea.

I use multiple smaller batteries because they pack easier in the dry box on my raft, they are easier to lug over rocks & sand to camp from the raft, and I can take just the number I need depending on the length of trip. If you are stationary car camping, then one larger battery would make more sense.

Also, I strongly advise that you buy the brand of cables that are meant for your system, and not "jerry rig" something. This will avoid any warranty issue that may arise in the future.

"Wet cell" deep cycle batteries are cheaper than sealed lead acid (AGM or gel cell) deep cycle batteries. The main drawback is that wet cell batteries can be spilled.

The battery box helps in case you spill some acid from the battery. SLA can leak, but they do so less often than wet cells.

Be sure any "marine" battery you get is a "deep cycle" marine battery. There are "starting" and "dual purpose" marine batteries that don't take a deep cycle as well as a true deep cycle.

A regular car battery can also work well, especially if you don't discharge it very deeply. If you discharge it deeply, it will still work, but it will have to be replaced more often. Depending on the price difference, and the number of trips you take, it might work as well as a deep cycle battery.

Thanks for all the info and feedback everyone. Its helpful to know whats working (and not working) for everyone, and the conversation helped a lot!

I went with the setup CapnLoki recommended. It seems to fit my particular needs the best. I did go with official respironics wires for connecting to my machine.

The only thing I don't feel like I have a good handle on at the moment is how to check the current charge. Like, if I've used it for two nights and I want to see if I can make it another night, What would be the easiest way to figure out the % of charge left? Everyone is always warning not to let it get too far discharged, so how do I make sure I'm not too low to avoid damage?

I bought this little volt meter, but it sounds like thats not really the best way to go about it: http://www.amazon.com/gp/product/B00962 ... UTF8&psc=1

blakepro wrote:...
The only thing I don't feel like I have a good handle on at the moment is how to check the current charge. Like, if I've used it for two nights and I want to see if I can make it another night, What would be the easiest way to figure out the % of charge left? Everyone is always warning not to let it get too far discharged, so how do I make sure I'm not too low to avoid damage?

I bought this little volt meter, but it sounds like thats not really the best way to go about it: http://www.amazon.com/gp/product/B00962 ... UTF8&psc=1

There are two ways to check the charge level. You can measure the the voltage, and try to correlate that with a state of charge, or you can measure the Amp-hours that have been used or recharged. I have never trusted the voltage, and when I live on my boat I check the Amp-hour meter (a $300 gadget) at least a dozen times a day. I mention a small AH meter (about $50) in:
viewtopic.php?t=102179
Unfortunately this can only tally charge or discharge, it can't do both at the same time. However, I've found for CPAP use the important thing is to measure the load of various settings, and this can only be done with an Amp-hour meter. Then its easy to figure how long the battery will last.

If you want to do it by voltage only, you have to watch out for inaccuracies. For instance, if you briefly charge a depleted battery, it may read a high voltage until you put a load on it. And a heavy load will make a battery read low. But if you always read just after turning off the load, then you should get a repeatable value. In addition, each battery has its own chemistry and its own "state of charge" curve so you'll have to work that out by trial and error. Google "agm state of charge chart" and you will get dozens of charts - take your pick. You might even try to track down the chart specific to your battery. Using these charts you should be able to measure charge state to within 10 or 20%.

Just to report. I don't have a fancy amperage hours reader or anything, so I'm relying on volt readings right after I wake up.

So far, this is what I can share.
I wanted to test just using my machine exactly as I do now. That's with the full 5 humidity setting. I knew this would tax the battery considerably, but I wanted to get a worst case baseline first.
Volt readings:
13.2 After full charge by battery tender
12.0 After first night (5 humidity setting) 6 hours of use
6.5 After machine died in the middle of the second night. (5 humidity) 5 hours of use before dying.

So it looks like I can get 11 hours of use with my settings on a 5 humidity level. Its charging up again. I'll try another round of nights at a 3 to see how far I'll get this time.