Finally got a battery!

[nomoore]

I finally got a battery. Yay!

I've been wanting to get a battery for a while, at least for the rare case in which the power goes out at night (hasn't happened yet in 8 months since I started therapy). Well my girlfriend decided she wants to go camping (yay, I love camping) so I had to buy a battery. So I researched it and ended up buying a small 12 volt deep cycle battery. It's about the size of a large motorcycle battery. It is Absorbed Glass Mat (AGM) technology so I don't have to worry about knocking it over.

The battery I bought is the Odyssey PC680. http://www.odysseybatteries.com/battery/pc680series.htm
The battery is 17 amp hours.
The CPAP.com battery is 6.6 amp hours and is listed as lasting 9.43 hours at a pressure of 13 (probably generous) on my Intellipap Auto.
9.43 divided by 6.6 = 1.42
1.42 times 17 = 24.14
That's 24.14 hours, right at three 8 hour nights. There's not much wiggle room there at three nights and I'm likely to sleep longer than 8 hours while camping anyway so I guess I'll figure that at 2 nights.

I also bought a "Battery Tender Plus" which is designed to work well charging an AGM type battery. I can also leave this charger hooked up forever with no ill effects. I made myself a DC cable using parts bought at Radio Shack and Auto Zone. My Intellipap Auto has a separate DC and AC input and will automatically switch to DC power when the AC power is lost. I tested this feature and it works great. I can hook up the AC and DC power to the Intellipap and the Battery Tender to the battery, set it and forget it. I am protected! WooHoo!!!

I bought both the battery and the charger online through Summit Racing Equipment
Battery Tender Plus - Part # DTN-021-0128
Odyssey PC680 Battery- Part # ODY-PC680

After shipping these two items cost me $193.85

The camping trip this weekend got canceled but we have others planned already. I will probably test my new setup soon.

[DreamStalker]

Sounds like a winning combo. I have the Battery Tender Plus too and like the easy hookup. Most definitely, test out the system at home before going camping.

I have done more than my lifetime share of camping in the past but realized that my camping days were pretty much over and I gave all my equipment away to my nephew a couple of years ago (I think the bug bit him ). Happy camping!

[carbonman]

I'm going to order my battery this weekend.

I'm going to go w/the Optima Blue top.
I like the size/weight of the Odyssey battery.
I have pretty much resigned myself that my camping
is going to be car camping, so for the cost/weight/performance
ratio, the Optima will work much better for me.

The thought of adding an extra 20#(battery,machine,etc)
to a backpacking trip is just out of the question.

I'm also going to get a solar charger, so when doing multi-day
camping trips, I can charge without power.

Thoughts/comments/suggestions

[DreamStalker]

I'm going to order my battery this weekend.

I'm going to go w/the Optima Blue top.
I like the size/weight of the Odyssey battery.
I have pretty much resigned myself that my camping
is going to be car camping, so for the cost/weight/performance
ratio, the Optima will work much better for me.

The thought of adding an extra 20#(battery,machine,etc)
to a backpacking trip is just out of the question.

I'm also going to get a solar charger, so when doing multi-day
camping trips, I can charge without power.

Thoughts/comments/suggestions

I too have the blue top Optima and am very happy with it ... although I have only tried for a couple of nights, I calculated about a week of use before I have to start worrying about getting it recharged should I be out of power for that long.

I'm very interested to know what setup you come up with for the solar charger.

[carbonman]

I'm very interested to know what setup you come up with for the solar charger.

This is what I'm looking at.
The RV/boater crowd are big into this solar stuff.
I'm thinking WAAAAAAY down the road....what if
the power grid goes down.

http://www.outdoorgb.com/p/solar_powere ... ountry=USA

http://www.siliconsolar.com/12v-solar-b ... 17859.html

[nomoore]

I considered an Optima but I wanted something I could take on a long motorcycle trip or maybe a short kayak trip. It shouldn't be too hard to wire it up to be charged by the motorcycle while riding.

I have also considered charging with solar power. I started looking into it and decided it would be WAY to expensive for me right now. Although the idea is still rattling around up there. I think some of the panels are pretty tough and waterproof. I wonder if I could rig up a solar charger to put on top of a Kayak. Hmmmm...

[DreamStalker]

I'm very interested to know what setup you come up with for the solar charger.

This is what I'm looking at.
The RV/boater crowd are big into this solar stuff.
I'm thinking WAAAAAAY down the road....what if
the power grid goes down.

http://www.outdoorgb.com/p/solar_powere ... ountry=USA

http://www.siliconsolar.com/12v-solar-b ... 17859.html

At 0.1 amp charge, you may need about 10 or 12 of those panels to charge during the day (w/ full sun) for one night of CPAP use.

[nomoore]

I'm very interested to know what setup you come up with for the solar charger.

This is what I'm looking at.
The RV/boater crowd are big into this solar stuff.
I'm thinking WAAAAAAY down the road....what if
the power grid goes down.

http://www.outdoorgb.com/p/solar_powere ... ountry=USA

http://www.siliconsolar.com/12v-solar-b ... 17859.html

Those would take WAAAAY too long to charge a battery. The battery I got is 17 amp hours and I figure it would last me 2.5 to 3 nights. Lets divide that by about 2.5 for a night of use by me. That's 6.8 amp hours used per night.

One of those chargers lists itself as 100mA or one tenth of an amp hour. So with ideal efficiency in the brightest sun it would take 10 hours to charge up one amp hour. It would take 68 hours to charge the 6.8 amp hours used in one night. That's not taking into account that the battery would need to be charged at a lower rate near the end of the charging cycle to completely top it off, therefore taking 1.5 to 2 times that amount of time.

You're going to need a bit more power. The 15 watt on the siliconsolar.com site might do it in a single day. 15 (watts) divided by 12 (volts) = 1.25 amps. That's the same output as my battery tender. It's probably not as efficient/quick a charge though. I need to test and see how long it takes for my battery tender to charge it after a night of use.

[timbalionguy]

A 15 watt panel is definitely going in the right direction. You might be surprised and find it is actually adequate, as their voltage increases as the load decreases. For a 'soft' power source like a solar panel, the battery will 'clamp' the voltage to a safe level near end of charge as long as the panel isn't too large and it is not left too long that way. If you really want good results, use a 20W or bigger panel with a battery charging controller.

I have several 38 amp hour gel cells that I use for astronomy and amateur radio. I intend to dedicate one to my IntelliPAP for backup power. I will use a charge tender or similar charger to keep it topped off. For camping, these batteries are heavy, but OK since anywhere I would go with them would be by car or truck.

Ultimately, I will have a large 12 volt battery system on float charge in my house for the ham radio setup. When that is complete, that will supply power to the IntelliPAP as well.

[nomoore]

A 15 watt panel is definitely going in the right direction. You might be surprised and find it is actually adequate, as their voltage increases as the load decreases. For a 'soft' power source like a solar panel, the battery will 'clamp' the voltage to a safe level near end of charge as long as the panel isn't too large and it is not left too long that way. If you really want good results, use a 20W or bigger panel with a battery charging controller.

I have several 38 amp hour gel cells that I use for astronomy and amateur radio. I intend to dedicate one to my IntelliPAP for backup power. I will use a charge tender or similar charger to keep it topped off. For camping, these batteries are heavy, but OK since anywhere I would go with them would be by car or truck.

Ultimately, I will have a large 12 volt battery system on float charge in my house for the ham radio setup. When that is complete, that will supply power to the IntelliPAP as well.

What is a "charge tender"? Is that a specific device or a generic name for what the siliconsolar website is calling a "charge controller"?

[DanJuan]

I considered an Optima but I wanted something I could take on a long motorcycle trip or maybe a short kayak trip. It shouldn't be too hard to wire it up to be charged by the motorcycle while riding.

I had some spare room under my gas tank so I installed an extra Oddysey battery that will charge when the bike is running. It, along with the bikes regular Oddysey battery should give me three or more nights and still be able to start the bike. Especially handy if I'm at a rally and don't ride much for a few days.

[billbolton]

The battery I bought is the Odyssey PC680. http://www.odysseybatteries.com/battery/pc680series.htm
The battery is 17 amp hours.
The CPAP.com battery is 6.6 amp hours and is listed as lasting 9.43 hours at a pressure of 13 (probably generous) on my Intellipap Auto.
9.43 divided by 6.6 = 1.42
1.42 times 17 = 24.14
That's 24.14 hours, right at three 8 hour nights. There's not much wiggle room there at three nights and I'm likely to sleep longer than 8 hours while camping anyway so I guess I'll figure that at 2 nights.

You should NOT discharge that sort of battery below 50% of capacity if you want a resonable service life out of it, which would mean ~12 hours usage, not ~24.

In any case, even if you tried to use 100% of the rated capacity, your CPAP machine will most likley cut out once the terminal voltage of the battery gets below 11V (or so), so you wouldn't get 24 hours out of it!

Also, you need to take notice of the chart on the web page you linked, which shows the actual capacity at the "20 hour rate" to 16AH at 25 degrees Celcius, with the final terminal voltage being 10.02 Volts, so the 17AH "headline" rating is somewhat misleading in any case.

All up, if you don't mind reducing the service life, you may get a couple of nights out of it at the stated current draw you have indicated, but even that might be a bit of a stretch!

Cheers,

Bill

[nomoore]

The battery I bought is the Odyssey PC680. http://www.odysseybatteries.com/battery/pc680series.htm
The battery is 17 amp hours.
The CPAP.com battery is 6.6 amp hours and is listed as lasting 9.43 hours at a pressure of 13 (probably generous) on my Intellipap Auto.
9.43 divided by 6.6 = 1.42
1.42 times 17 = 24.14
That's 24.14 hours, right at three 8 hour nights. There's not much wiggle room there at three nights and I'm likely to sleep longer than 8 hours while camping anyway so I guess I'll figure that at 2 nights.

You should NOT discharge that sort of battery below 50% of capacity if you want a resonable service life out of it, which would mean ~12 hours usage, not ~24.

In any case, even if you tried to use 100% of the rated capacity, your CPAP machine will most likley cut out once the terminal voltage of the battery gets below 11V (or so), so you wouldn't get 24 hours out of it!

Also, you need to take notice of the chart on the web page you linked, which shows the actual capacity at the "20 hour rate" to 16AH at 25 degrees Celcius, with the final terminal voltage being 10.02 Volts, so the 17AH "headline" rating is somewhat misleading in any case.

All up, if you don't mind reducing the service life, you may get a couple of nights out of it at the stated current draw you have indicated, but even that might be a bit of a stretch!

Cheers,

Bill

Thanks for the heads up!
That's interesting that they rate it that way considering they say 11.5 volts is fully discharged in the documentation section. It really is misleading. They do mention that their batteries can take 400 charge/discharge cycles up to 80% depth of discharge though instead of the 50% that you mention. I'm anxious to see what state of charge it has after one night. I need to borrow my dad's digital volt meter.

On a different site I see that 11.58 volts is generally considered a 20% charge for AGM batteries. It makes sense to me that they would say 11.5 is fully discharged so you don't go below the max 80% depth of discharge.

http://www.windsun.com/Batteries/Batter ... 0Batteries

So basically it looks like I need to take the 16 amp hour rating from the chart and drop that by 20% to get the 80% depth of discharge.

16 times 0.8 = 12.8 amp hours

so 1.42 times 12.8 = 18.176 hours of run time to ~11.5 volts

That's still 2 nights of use. That's what I was aiming for.

[billbolton]

They do mention that their batteries can take 400 charge/discharge cycles up to 80% depth of discharge though instead of the 50% that you mention.

Its your call what you do with it, but I've yet to see a AGM battery that gives what I would call a reasonable service life it is regularly discharged to 20% of capacity.

• Battery life is directly related to how deep the battery is cycled each time. If a battery is discharged to 50% every day, it will last about twice as long as if it is cycled to 80% DOD. If cycled only 10% DOD, it will last about 5 times as long as one cycled to 50%. Obviously, there are some practical limitations on this - you don't usually want to have a 5 ton pile of batteries sitting there just to reduce the DOD. The most practical number to use is 50% DOD on a regular basis. This does NOT mean you cannot go to 80% once in a while. It's just that when designing a system when you have some idea of the loads, you should figure on an average DOD of around 50% for the best storage vs cost factor (from the same web site that you linked)

Cheers,

Bill

[carbonman]

How do you know you have really accepted your cpap therapy?

When you are excited to get new cpap stuff.

I pulled the trigger on my Optima Blue top yesterday.
Should be here next week. YaHooooo!

Last week I got a new seal for my mask.
I counted the days til it came.

billbolton, you're very knowledgeable about batteries and such,
what are your thoughts on a solar charging solution??