Got my battery now a few battery 101 questions

[TheresaD]

Please be patient here... This could get lenghty. I have read through as many of battery related threads as I think I can digest at the moment and I think I get most of the info. I do have a few random questions though. I just bought an 85AH deep cycle marine battery so that I can power my CPAP machine when camping without hookups. At present I don't have anything in my trailer that runs off of any kind of power. (Haven't gotten that far yet) For right now this battery will be dedicated to my cpap. So here are my questions.

Where should I look to find one of those battery boxes that I see folks using to put their batteries on the tongue of their trailer? I don't have a tongue box. The place that I bought my battery does batteries and that's it. He didn't have any of those boxes there. Would this be something that's fairly easy to find at Wally world or Harbor Freight or a big box store? Not sure where to look for these.

I'm assuming that once the battery is in said box that there are ports of some sort that the cables go into to hook up to the battery? Do any of you have any special secret way of attaching these to the tongue. A friend of mine is going to weld a cross piece into the A-frame to serve as a mounting bracket. What would you use to secure the box?

You all talk about how much your battery has discharged after using it. How do you know this? (Remember I'm a total rookie with this) Are you getting up in the morning and doing the math? (please tell me no! I hate math) Is there some sort of meter that I should get so that I can check this? If so is it something that gets mounted to the battery or is it just a tool that you put to the terminals to check it?

I bought the battery Saturday. Since it's sitting and hasn't been used yet will it still be at 100% capacity when I go to use it at the end of the week or should I have it hooked up to a tender/trickle charger right now so that it will be at full power when I go to use it at the end of the week? I should mention that I won't have it completely hooked up to the tv for the first use so it won't be getting charged while I drive. I will merely have the battery with me in the truck and will hook up to it when I get to where I'm going. Should it always be on the trickle charger when I'm not using it?

What should I consider too low before I need to recharge the battery? Assuming I have mastered the math or have gotten some sort of meter that will tell me how low it is. If I get really low at the weekend is it as simple as hooking jumper cables up to my truck and the deep cycle and charging it that way to bring it back up?

Thanks in advance for your patience with these remedial questions. Eventually I'll get my head around it all.

[Shadow Catcher]

Ignorance is curable, Best to ask questions.

Where should I look to find one of those battery boxes that I see folks using to put their batteries on the tongue of their trailer?
I got my present one from an RV supply, also available on line.
I don't have a tongue box. The place that I bought my battery does batteries and that's it. He didn't have any of those boxes there. Would this be something that's fairly easy to find at Wally world or Harbor Freight or a big box store? Not sure where to look for these.

Wall mart may have it on line, or Amazon or...

I'm assuming that once the battery is in said box that there are ports of some sort that the cables go into to hook up to the battery?
Yes
Do any of you have any special secret way of attaching these to the tongue. A friend of mine is going to weld a cross piece into the A-frame to serve as a mounting bracket. What would you use to secure the box?
Many come with a belt that hold them in place.

You all talk about how much your battery has discharged after using it. How do you know this? (Remember I'm a total rookie with this) Are you getting up in the morning and doing the math? (please tell me no! I hate math) Is there some sort of meter that I should get so that I can check this? If so is it something that gets mounted to the battery or is it just a tool that you put to the terminals to check it?
The battery needs to be checked with a meter and the voltage will tell you the state of charge http://www.batteryfaq.org about half way down the page or http://www.marxrv.com/12volt/12volt.htm neither require math
You do not want to let it get below 50% if you can help it (shortens its life).

I bought the battery Saturday. Since it's sitting and hasn't been used yet will it still be at 100% capacity when I go to use it at the end of the week or should I have it hooked up to a tender/trickle charger right now so that it will be at full power when I go to use it at the end of the week?
It is probably not at full charge and yes you will need to charge, this is a good time to use a meter (practice) to see its state. It has to be some hours after charging to be read.
I should mention that I won't have it completely hooked up to the tv for the first use so it won't be getting charged while I drive. I will merely have the battery with me in the truck and will hook up to it when I get to where I'm going. Should it always be on the trickle charger when I'm not using it?
Depends on the charger, some will maintain others not.

What should I consider too low before I need to recharge the battery? Assuming I have mastered the math or have gotten some sort of meter that will tell me how low it is. If I get really low at the weekend is it as simple as hooking jumper cables up to my truck and the deep cycle and charging it that way to bring it back up?
Jumper cables will help but will not likely get the battery up to full charge, if you can use the charger

Thanks in advance for your patience with these remedial questions. Eventually I'll get my head around it all.

The http://www.batteryfaq.org has the most complete up to date information I have found on care and feeding of deep cycle batteries. Go have fun take pictures and let us know how it works out.

[dh]

Where should I look to find one of those battery boxes that I see folks using to put their batteries on the tongue of their trailer? I don't have a tongue box. The place that I bought my battery does batteries and that's it. He didn't have any of those boxes there. Would this be something that's fairly easy to find at Wally world or Harbor Freight or a big box store? Not sure where to look for these.

Wall-mart has them on the shelf in the automotive and sporting goods departments.

I'm assuming that once the battery is in said box that there are ports of some sort that the cables go into to hook up to the battery?

The lid to the box has provisions to fit over the cables.

Do any of you have any special secret way of attaching these to the tongue. A friend of mine is going to weld a cross piece into the A-frame to serve as a mounting bracket. What would you use to secure the box?

The box should come with a bracket and strap. The bracket bolts to the mount and the strap runs through it and over the box. The box will come with mounting instructions.

You all talk about how much your battery has discharged after using it. How do you know this? (Remember I'm a total rookie with this) Are you getting up in the morning and doing the math? (please tell me no! I hate math) Is there some sort of meter that I should get so that I can check this? If so is it something that gets mounted to the battery or is it just a tool that you put to the terminals to check it?

There are many ways to do this. The voltage across the battery terminals tells you how discharged it is. If you have a 12v cigarette lighter style outlet in the cabin, Wall-Mart has a simple battery meter that will plug into it and display battery life on a "fuel guage"

I bought the battery Saturday. Since it's sitting and hasn't been used yet will it still be at 100% capacity when I go to use it at the end of the week or should I have it hooked up to a tender/trickle charger right now so that it will be at full power when I go to use it at the end of the week? I should mention that I won't have it completely hooked up to the tv for the first use so it won't be getting charged while I drive. I will merely have the battery with me in the truck and will hook up to it when I get to where I'm going. Should it always be on the trickle charger when I'm not using it?

The battery was sitting a lot longer than that on the shelf before you bought it. I would charge before using in your application.

What should I consider too low before I need to recharge the battery? Assuming I have mastered the math or have gotten some sort of meter that will tell me how low it is.

The popular opinion around here seems to be around 12V.

If I get really low at the weekend is it as simple as hooking jumper cables up to my truck and the deep cycle and charging it that way to bring it back up?

Refer to the sticky "charging while towing" linked below

http://tnttt.com/viewtopic.php?t=28620

Thanks in advance for your patience with these remedial questions. Eventually I'll get my head around it all.

Don't sweat it!

[eamarquardt]

Here's an interesting article.

http://cchipman.com/cpap_on_batteries.htm

You shouldn't follow the example in the article and run your battery down to the level he does. The degree to which he drew down his battery, if a constant practice, will be hard on your battery and its performance will eventually be degraded and you will see a shortened battery life and premature failure.

With a 100 amp hour battery you shouldn't run it down past using 50 amp hours or roughly two night useage if your's uses about the same amount of power as his (if all the battery does is power your cpap).

You shouldn't charge a battery at more than 10% of it's amp hour capacity so you should plan on a bit over two hours at 10 amps as a minimum time to properly recharge your battery after a single night's useage.

Sizing the battery and using it, IMHO, is the easy part. The important part is how your gonna properly charge it with the right current over an appropriate amount of time for reliable service and so that you obtain a reasonable service life out of your battery.

After you size a battery for a project, properly charging the battery is the hard part, IMHO.

Your camping style (hookups or not), driving style (touring a lot during the day), solar, generator, etc. will determine what approach works best for you. Simply hooking up your cpap battery to your car battery for some period each day isn't going to be, IMHO, a viable solution to recharging your battery. The proper care and feeding of a battery is important if you want to get good service (reliable power and reasonable battery life) out of your battery.

Hope this helps.

Cheers,

Gus

[dreadcptflint]

Theresa,

There is nothing wrong with being a rookie especially if you keep asking questions you will be an expert before you know it. Here is my set up:



Yes, I doubled up some 3/4 in plywood and bolted it to my frame. I also stained and under coated it. (I was really intrigued by the whole woody concept and wanted to see what it would do). My Battery box and cabinet were purchased on eBay.

I have a gauge in the cabinet that is linked to my solar charger. An easy way to do it is get a gauge that you plug into the outlet. If you charge the battery when you get home and make sure that it is charged when you leave then you should be fine. I was able to run my battery four nights just using my CPAP and no charger so you should be OK with just a couple of night running just your CPAP.

You are in for some fun.

Matt

[TheresaD]

Thanks for all the replys guys. I really appreciate it. (Gus, I got your pm earlier but I'm just getting time to reply now.)

I will check out Wally World for a battery box. We don't have any super centers near me so hopefully the regular one will have them.

Will pick up a meter while I'm there.

For those of you that understand this stuff - I am using a Resmed S9 Autoset machine. Average usage is 6 1/2 - 7 hrs per night at average pressure of 11-12 with EPR setting of 1(low).
That being said, I don't really know what the power consumption is while I'm using it. I am currently checking out Resmed's site to see if I can get that. If I can find that I'll be in better shape. I think I'm getting a better understanding of how to calculate the amps thanks to everyone on here.

I am somewhat confused still with regard to what is a safe level to draw the battery down without compromising it. I was under the impression that deep cycle batteries could be drained down lower than 50%. Is this not the case? For the record, I don't have a gell/mat battery. Mine is the type you add water to. The limited info that I found with the machine recommended a 50AH or higher battery to operate it. I went with getting an 85AH battery for a couple of reasons. It was more in the price range of what I could afford, it was more than recommended, and it was also within a weight range that I could lift myself without too much difficulty (don't have the best back). I'm hoping that 85AH will get me through at least 2 nights and more desireably 3 without charging. Based on what's being said here, it's sounding like 3 might be pushing it. I will be using the battery solely for the cpap. I guess this weekend will be a good test. I will need it for 2 nights. Then I'll need it for 3 the following weekend.

If I'm understanding things, using the jumper cables and the truck is not an optimal way to charge without compromising the battery. Might have to look into solar alternatives for when I'm without power. Can a generator be used for charging? I don't prefer to listen to one, but if I needed to I could borrow one from my friend temporarily.


Matt - how many AH is your battery? Were you running your humidifier? (BTW nice set up!)

Again... thanks all for your patient explanations... It is starting to sink in.

[dh]

I re-read, looks like nobody hit the keeping the battery on the trickle charger. I use a maintainer on a battery in storage, as in durring the off season. When I was living farther north, the lawn tractor would come off and the snow blower would go on.