How can I run a CPAP in my tiny van?

[SternWake]

I'm sorry, but I'm done.


It's one thing to repeat oneself over and over responding to people who can't seem to do a search and think no one ever has had their same question, but to have to repeat oneself over and over to the same person, in the same thread and on multiple threads covering the same subject  is too much.

 

[amwbox]

I'm sorry, but I'm done.


It's one thing to repeat oneself over and over responding to people who can't seem to do a search and think no one ever has had their same question, but to have to repeat oneself over and over to the same person, in the same thread and on multiple threads covering the same subject  is too much.

You need a word doc or something so you can quickly paste in blocks of info.

 

[BigT]

I'm sorry, but I'm done.


It's one thing to repeat oneself over and over responding to people who can't seem to do a search and think no one ever has had their same question, but to have to repeat oneself over and over to the same person, in the same thread and on multiple threads covering the same subject  is too much.

The problem I'm having is that your answers are 50 paragraphs long and way too tech-heavy.  

All I wanted was a simple answer to my question, but instead I got a overly-long reply with too much information to absorb, at least for the layman.  
I find myself reading your replies over and over, trying to find the part that addresses the question I asked.  

Instead of a clear and consise answer, addressing the key points in simple, layman's terms, I get a reply that reads like an engineers textbook with far too much information for someone just starting out to take in.  

I'm also seeing replies that suggest you're not reading my posts, or perhaps misunderstanding them.  (sorry, but I'm not going back 11 + pages to quote where you replied to a question I never asked).  

I do thank you for your help, though.  I'm sure if I do a few searches I'll find an answer to my last question.  And someday, when I'm ready to install an AGM in the back of my van, connected to solar and the alternator, I'll know just where to look for my answers.  

 

[akrvbob]

If I connect my 190W panel via my MPPT cc to my OEM, under-hood 12V battery, and maybe buy one of these (just in case)  http://www.amazon.com/gp/product/B0...rd_t=36701&pf_rd_p=2090149782&pf_rd_i=desktop , would that be OK for powering a .35 - .50 (estimated) Amp-per-hr. CPAP, or would the OEM battery suffer a painful and premature death from repeated, albeit occasional and minor, cycles?  

Or have I beaten this to death so badly that if I ask one more question you'll send someone to my house with a bazooka?

No, don't use the starting battery, almost universally we agree to not use the starting battery if you can afford a house battery.

Don't put the house battery under the hood, too hot, batteries don't like heat. But eve more it's not worth the mental anguish it will cause you.

Keep the 190 watt panel, keep the controller you have, put the AGM battery in the back and hook it up.

You are done. You've done the best job you can and now it's out of your control. The battery will last as long as it will last and then you will replace it. Is spending a little more money to replace the battery really worth all this mental anguish you have put yourself through? 

Have you done any research into the principles of Zen? I think you may be a candidate for them. Of course I think everyone is a candidate for them, but you specially 

Bob

 

[SternWake]

I can't give a yes or no answer when the answer is "it depends".

If the 'It depends' part is not written so you cannot understand it, I can't help you.

I'm told, that with my writing style, than pausing for the commas, is key to getting the jist of it all.

Best of luck Big T.

 

[BigT]

I can't give a yes or no answer when the answer is "it depends".  

If the 'It depends' part is not written so you cannot understand it, I can't help you.

I'm told, that with my writing style, than pausing for the commas, is key to getting the jist of it all.

Best of luck Big T.

Thanks for all your help.  I really do appreciate it.  

And just so you know that I do listen to and take your advise...  I'm installing an AGM in the back of the van and connecting it to the alternator & panel.  

-T

 

[BigT]

It looks like shadowing won't be as much of an issue as I feared.  I was able to push the panel and kayak apart far enough that the boat shouldn't cast a shadow 'till late in the afternoon/early in the morning (depending on which way I'm facing).  

Now to see what kind of gas mileage I get with all this crap on the roof. :s

 

[BigT]

Well it works.  In fact I'm cycling the battery so little when I run the CPAP, I'm not sure the panel is even doing anything.  I'm not really sure how I'm supposed to tell, though.  There are three lights on the charge controller that tell whether the battery is fully charged, half charged, or nearly empty, and so far the light indicating a full charge has never changed.  
How do I tell if the charge controller is letting Voltage through to the battery?  

Another possible issue that was discussed in this thread was the possibility that the Acc plug could heat up while running the CPAP all night.  
So far this doesn't seem to be an issue at all.  I ran it for 9 straight hours last week while camping at a KOA in Manchester Beach, Ca. and checked it the moment I turned the unit off in the morning.  The plug wasn't even slightly warm.  

Sometimes I wonder, given its current usage (1 or 2 nights a week on occasional weekends away), if I really need a solar panel at all.  
On my last trip I used the CPAP for 9 hours on Friday night, then drove 23 miles south and used it again on Saturday night for another 7 hours.  The light on the charge controller never changed.  

I'm not planning to remove the panel and cc, but I do wonder if it's even doing anything.  

 

[SternWake]

Get yourself a clamp on Ammeter, something like this:

http://www.amazon.com/Uni-T-UT210E-...=1441610591&sr=8-3&keywords=uni+t+clamp+meter

Clamped over one wire, not both, it will show the current running through the wire.

It is also a full function digital multimeter, so you can see battery voltage too.

Ideally, You want to see battery voltage rise to 14.46v from the solar, and be held there until amps taper to 0.38 amps, then drop to 13.6v float. I am not familiar with your solar controller at all.

The Clamp on meter can be used to see how much current the Cpap pulls, or any other load pulls as well.

Just keep an eye out on the Ciggy plug. When you notice you have to wiggle and twist it to get it to stay put and pass current, which will happen, it is just a matter of time, then you can consider replacement with something more durable and efficient, like Anderson powerpoles.

For now, enjoy, and congratulations.

 

[BigT]

Thanks for the tip on the meter!  I've been needing a new multimeter for years, and this one seems like it has nice options, like the clamp.  

Morningstar has a digital meter I can plug directly into my charge controller, but it's $90.  This multimeter seems like it will do the same (mostly) job and have the added advantage of being used for a lot more than just my solar.  

After reading Amazon reviews of this model, and finding out that some models don't read DC Amps, I've added it to my shopping cart. 

 

[SternWake]

I've no experience with that particular meter I linked, I just knew that brand was among the cheapest that could measure both AC and DC current.  Most cheaper clamp meters can only to AC.


They are awesome to have and a great learning tool but my link was not a particular  product endorsement, merely an economical example of such a product.

Let us know how it works out for you and what your system is outputting, but you might have to drain the battery further to see the panel put put its maximum at solar noon.  If it is already  above 85% or so by the time Solar noon approaches, you will not see the maximum panel output.

With the clamp meter you can see panel output rise when you clean it off with cool water, if you take readings quick enough.

Make sure to use Alkaline batteries in the clampmeter.  Nicad or Nimh rechargeables will throw off readings as they are lesser voltage even when fully charged, and while NImh can maintian higher voltage at higher rates of discharge than alkaline and be perfectly functional in most devices, a Multimeter is not one of them.

My Sears clampmeter accuracy was way off with Nimh''s installed.

 

[BigT]

I've no experience with that particular meter I linked, I just knew that brand was among the cheapest that could measure both AC and DC current.  Most cheaper clamp meters can only to AC.


They are awesome to have and a great learning tool but my link was not a particular  product endorsement, merely an economical example of such a product.

That model gets really good, mostly 5-star, reviews on Amazon, but they claim a $124.00 savings if purchased through them.  Not sure I believe that.  Sounds a little too good to be true, and things that sound too good to be true often are.  

I found another, slightly cheaper model on Amazon, but after reading a review from a solar installer who bought one, I found out that it didn't measure DC Amps. 
I long ago learned to read the reviews and answered-questions on Amazon before hitting the "Submit Order" button.  Good stuff in there.

 

[SternWake]

I long ago learned to read the reviews and answered-questions on Amazon before hitting the "Submit Order" button.  Good stuff in there.

Agreed, but there is also some bad information too.  Usually this is easy to disregard as it is written poorly or otherwise shows the reviewer to not be the sharpest chisel in the drawer.  Sometimes reviews include separate slightly varying products too, and might not be applicable to the exact product purchased/desired.

My clamp meter has been an awesome tool in helping others and myself to better understand their/my DC systems and to confirm my other gauges, whether voltage or amperage.  I make a guess at amp flow, then check my guess and either I am close, or I overlooked something, or something is wrong.  All learning experience.

My buddy's batteryminder 12248 charger appears to be working perfectly, all the lights come on and do their thing, but it no longer produces any current.

Sure a simple voltmeter could indicate no charging has occurred, but seeing 0.00 amps flowing when 8 amps should have been flowing convinced my friend it had failed,  where as battery voltage alone could and did not.

Once you get the clamp meter, and employ it and experiment with it, your understanding of and confidence in your DC system will increase ten fold in the first week.

 

[GotSmart]

I bought this, and it gives out just enough information so I do not panic.  I can tell when something is wrong and get out the serious equipment.

http://www.amazon.com/gp/product/B000EVWDU0?psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00

 

[offroad]

I bought this, and it gives out just enough information so I do not panic.  I can tell when something is wrong and get out the serious equipment.

http://www.amazon.com/gp/product/B000EVWDU0?psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00

That's what I have.

 

[BigT]

But that's just for Voltage, isn't it?

 

[GotSmart]

Dont get too crazy about your system.  Tat shows when you have a drop or increase, and what is wrong.  It is a cheap way to monitor things.  After  using it for a couple days, you will be able to te when everything is normal or as a problem.  (This from a guy with fuses on everything!)

 

[NeedAnEscape]

 (This from a guy with fuses on everything!)

Having properly sized Fuses on everything is always a good thing. The worst thing your solar system can do if it doesn't properly charge your batteries is wear out the battery quicker. A short without proper fuses can result in this:

 

[GotSmart]

That is why I have my fuse box fused.  :s

 

[SternWake]

Some vehicles will have other loads shared on the circuit which feeds the Ciggy plug receptacle, and if these loads are on, it will throw off the voltage reading on a voltmeter plugged into the dashboard ciggy receptacle.

A digital multimeter is a great too to have, A clamp on Digital multimeter is significantly better in this lifestyle as one can then test the current draw of any single device or the charging current from any charging source.

The more measuring tools the better. Since BigT only has one single battery underhood, the surface charge left over from the alternator after a drive could have voltage reading higher allow him to believe the solar system is responsible for the higher voltage, even if the solar system was doing nothing due to an open circuit or a faulty controller.

I have 2 of these on my dashboard:
http://www.amazon.com/DROK-Digital-...qid=1441734434&sr=8-2&keywords=drok+voltmeter

One for each battery, but they are wired to only come on with the ignition, and they are enlightening.

By all means, employ voltmeters and keep an eye on them, but they are hardly a gas gauge. A voltmeter relates to battery state of charge on a battery still in use, the same way one can judge how much a rock weighs by throwing it at a rubber band, and seeing how far it stretched.

Also be sure to compare any given voltmeter to a known accurate meter before just trusting it. A 0.1v difference is huge.

But one can argue, 12.8v+ battery is charging, 12.8v or less, it is discharging, and that is all some ever care to know.

Big T's Northstar battery will have a fully charged resting Voltage above 13v. That Innova voltmeter says anything above 12.6v is 100% charged.

12.6v resting on his Northstar battery is anything but fully charged.
The voltage trap is an evil one. Skirt the edges of it.