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[Equipment] Calling all electronics experts....
#1
Calling all electronics experts....
Hello all
I am starting this thread in the hopes of resolving an intriguing problem when running a Philips Dreamsation on a 12 volt cable which is connected to an Ecoflow River Pro portable solar generator. I have noticed threads on this forum talking about making custom cables and running CPAP machines of USB-C so I am hoping some experienced people could give their input and together we can solve the issue.

My story starts with the need to run my Dreamstation whilst camping. initially I had purchased the genuine Philips 12 volt cable and built myself portable battery by combining a cheap battery box and a car battery. This worked well and got me through the trip, however it had some drawbacks. 

I started to investigate alternative solutions such as the official Dreamstation battery pack but found it quite expensive for what it was, so I looked at other options and settled on an Ecoflow River Pro, this unit ticked a lot of boxes for both CPAP and non-CPAP usage.

So I was about to head off on a camping trip and decided to do a test run of my Dreamstation prior to leaving. I connected the 12v lead turned all heaters and humidifiers off and started the test. Everything was going OK, current draw was fluctuating between 0 and 30 watts and it ran like this for about 10 minutes. Then the Ecoflow shut down with an on screen alert saying "Overload" how was that possible? I then restarted the test and sure enough a random amount of time later the overload light came back on and the Ecoflow shut down. 

I repeated the test a few more times looking for a pattern and noticed the Ecoflow shutting down as the wattage dropped to 0. I then turned the heated hose to 1 which increased the current draw by 10 watts so it was fluctuating between 10 and 40 watts. It ran OK for a few hours at least until the hose heater cycled off and the current dropped back down again. So it seemed that increasing the device load prevented the overload warning.

I thought maybe the 12v port is faulty so I plugged in my Engel camp fridge and let it cycle all night with no issues, it was drawing 130 watts peak so the Ecoflow can supply the power when needed. I also tried a 12v laptop charger and watched the current draw drop from 60 watts to 0 as the laptop charged, again no issue. 

I reached out to Ecoflow tech support but just got basic support that didn't help, once they learned it was a CPAP device they basically just said it is not supported and washed their hands of it. 

I then posted in the Ecoflow facebook group and found a gentlemen an Tennessee that had the exact same issue when using the dreamstation on 12v also, he confirmed that using a Jackery solar generator resolved the problem so it appears the issue is endemic to the Ecoflow device when coupled to a dreamstation.

So as far as I can tell there is something about the load profile of the dreamstation that is triggering the over current protection falsely in the Ecoflow. I have tried crudely replicating the load profile with LED strips and switching them on and off but was unable to get the unit to trip out. The other thought I had was to build a load simulator using a brake light globe from a car, a 555 timer and power transistor to slowly fade up and down the light globe in an attempt to simulate the dreamstation load, that was I could engage Ecoflow tech support as I was no longer talking about issues with a medical device. 


Initially I thought maybe there was some RF noise or AC ripple coming from the dreamstation so I put a 1 farad capacitor across the 12v supply but no luck on that front. 

I took a video to demonstrate the issue. 
Link removed as I don't have 4 posts yet, however if you are a smart cookie: watch?v=NxY6S_tZhZ8



Does anyone have any suggestions on where to next? I was thinking of maybe putting an oscilloscope on the 12v rail to see if there are any voltage spikes, as the issue seems to happen when I exhale and the current drops. If that could be proven then perhaps I could build some sort of filter or add some diodes.

Thanks.
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