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  1. #21
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    https://cloud.tapatalk.com/s/58d87128...326_225137.mp4
    Here's a video of my CPAP while measuring the DC current. Sorry I had to keep the video extremely short to keep it below the file size restriction but fortunately it is more than long enough for this demostration

    I have the CPAP pressure set to 15cmH2O. The machine requires about 1.5 amps. The video also shows the current dropping to about .5 amps while I breathe out - this is due to the A-flex feature that reduces the pressure every time I exhale. I would say that this is one feature that definitely saves on batteries..

    Sent from my SM-A500W using Tapatalk

  2. #22
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    I couldn't playback the video. Not sure what is wrong. I hope you have better luck.

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  3. #23
    Senior Member BigE94's Avatar
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    Quote Originally Posted by Tyler883 View Post
    I couldn't playback the video. Not sure what is wrong. I hope you have better luck.

    Sent from my SM-A500W using Tapatalk
    Video played perfectly on my end. Thanks for that. So if the CPAP only needs 1.5 amps then I wonder why a 4amp unit wouldn't work. Again... above my head.
    I would rather be in the woods... my dog would rather be in the pool. My wife thinks we are both nuts.

  4. #24
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    I just tried the same measurement at 17 and 19.5

    The current does not noticeably change. While it makes sense that it would change. It also makes sense that the current has more to do with the way the mask on my face creates a load on the blower.

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  5. #25
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    Also, sorry, I'm not able to capture the start up current. The shunt on my ammeter is causing the CPAP to reset during start up. I actually have to short the ammeter leads to get the CPAP to startup.

    I see a 2.xxx reading flash across the screen but frankly it is not a reliable measurement.

    the 5 amp figure that you mentioned seems more reasonable.

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  6. #26
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    Lithium batteries are smart batteries in the sense that the require a battery management board (BMS) to prevent the battery from blowing up or catching on fire.

    Some of the things that the BMS board controls are:
    - high voltage cutoff
    - low voltage cutoff
    - high current cutoff
    - low current cutoff

    Your battery probably exceeds it's high current cutoff limit during startup. Meaning that the BMS is restricting the maximum current from the battery which would cause a brown out....the CPAP resets due to the brown out.

    You could probably create a work around by using a decoupling capacitor across your battery terminals. The capacitor would provide the high current that is required during startup.

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    Last edited by Tyler883; 03-26-2017 at 22:05.

  7. #27
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    Another thing you could try is turn the CPAP on while the mask is not on your face, then place the mask on your face. This doesn't work to bypass my current meter problems but you might have success with your battery.

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  8. #28
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    Quote Originally Posted by BigE94 View Post
    That is awesome and looks like something I would put together. You when you build a rig like that to transport a huge lead acid battery you have proven that you will do anything to go camping. I think with the lipo battery choices available now you could switch to something a lot smaller.... A lot smaller. I did see some solar options for the smaller battery in my OP. Would be interested to hear your thoughts. I'm thinking about a multi-day backpacking trip in July and solar charging would be great.
    I have a 24 watt solar panel which in ideal conditions can produce 2 amps. If my CPAP is using 2 amps for 7 hours then it would take my panel about 7 hours in ideal conditions to return that power to your battery. But there are a few reasons why this is only a crude guestimate.

    - the solar panel will likely never see ideal conditions. Personally, I like to consider the panel capable of performing at half its ideal capabilities. But this is just an arbitrary number. Someone in a rainy envi4ement might never see 50% of ideal conditions.
    - the charger controller that comes with my solar panel only charges my batteries to 12.8volts. This is rated output voltage for my lead acid batteries. If you check a website like battery university dot com, the lead acid battery is not fully charged until it receives a charging voltage of 14.45volts until the charge current drops to low number, for example 120mA. The formula is something like C/100.
    - as a battery get close to its full charge, the charge current decreases. Which means charging a cellphone to 80%, using it, then charging it to 80% again might take less time than charging it to 100%.

    Anyway, to summarize my system... it never provides a 2 amp charge and never charges my battery to full capacity in 1 day. And I'm estimating that a 15 hour charge time creates a sustainable system. But frankly, I'm doing a 10 day jamboree this summer and my system scares me. I met have to rely on a 110v charging station.



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    Last edited by Tyler883; 03-26-2017 at 22:37.

  9. #29
    Senior Member P-Dub's Avatar
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    The generic term is "oral appliance" -- there are many brands.
    Here's some information: http://www.aadsm.org/oralappliances.aspx

    You cannot buy a drugstore type and expect it to work. The movement of the lower jaw needs to be measured, and the distance that it is pulled forward by the appliance is determined specifically based on that. Different for everyone!

    Best advice: find a dentist who is an expert in dental sleep medicine:
    http://www.aadsm.org/FindADentist.aspx?1

    Good luck!

  10. #30
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    My son's orthodontic work has started with elastic bands. If an elastic band can move teeth, I wouldn't use an oral appliance without a doctor monitoring my therapy.
    I like the idea of an oral appliance. No batteries. No charging problems. No noise.

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