Author Topic: Moteino sleep issues  (Read 1470 times)

malik

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Moteino sleep issues
« on: November 05, 2019, 03:52:35 PM »
I have had bunch of Moteinos running with RFM69hW, most of the devices are sleeping properly, giving about 10uA sleep current which is what I expected.
I have noticed after few months one of the Moteino started draining the battery quicker, upon inspection, I realised its using 300 uA which is odd, considering rest of the units have same hardware and firmware. So to make sure its RF using the excess current, I have de soldered the RF module (Not fun Job), and I noticed current draw went to normal. As a test I solder this RF module onto a breakout board and checked the draw again and result showed higher current draw.

Now I have couple of questions here.

1. Why this problem started after few months of use,
2. What is best way to debug this module to find the source of leak.




Felix

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Re: Moteino sleep issues
« Reply #1 on: November 05, 2019, 07:09:26 PM »
How old is this RFM69HW module? I have not been selling HW modules for years now, only HCW.
Sounds like this is restricted to a single module.
Can you make that same module go back to 10uA sleep current? Or will it always draw 300uA?

Could it be corrosion developed on the flux residue of the radio module? Can you inspect that under a microscope for such corrosion?

If it's just an isolated case like this, and it's not some obvious cause, then I can't be sure. AFAIK these radio modules contain genuine Semtech SX1231h chips, but are packaged in china, with love, and a huge amount of corner cutting, but at prices we all also love.

So ...... after saying all that, if that would happen to me, I would swap the radio modules, and keep an eye on that same node, to see if the same behavior repeats ever again.

malik

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Re: Moteino sleep issues
« Reply #2 on: November 06, 2019, 04:40:31 AM »
It’s fairly old, but it’s been in service only few months. Corrosion is possible, because units are exposed to harsh conditions, like underfloor to monitor the tem/humidity. When we take them out we see a lot of dirt on them. Also we have lacquer the main board. Is it  possible lacquer is causing this.

Felix

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Re: Moteino sleep issues
« Reply #3 on: November 06, 2019, 08:42:30 AM »
Depends what laquer you use and what is actually corroded.
Unless you completely encapsulate the board in protective enamel/laquer, there is a fair chance they get damaged from exposure, and that behavior would then not be surprising.

malik

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Re: Moteino sleep issues
« Reply #4 on: November 08, 2019, 06:27:43 AM »

TomWS

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Re: Moteino sleep issues
« Reply #5 on: November 08, 2019, 08:30:10 AM »
FWIW, I have found that CorrosionX, mentioned in previous posts on this forum, works extremely well at preventing corrosion.  I have tried lacquers, potting, and various other methods, but have found this the most effective of all methods.  It's messy, yes, but that's one of its benefits - it seeps into every crevice to seal against moisture.

As an extreme example, I have one device, which is a dosing pump to dose my man-made stream with algaecide, where I have an ESP8266 and various other electronics in the same enclosure as the pump.  I had liberally coated the circuit boards and motor contacts when I assembled it and it has been operating reliably for the last two years.  I was stunned, when I went to refill the tank at the end of summer to discover that the tubing fittings had leaked and the circuit board was actually partially covered in liquid (either condensation or algeacide, I don't know), but it was still operating without any sign of corrosion.  Now THAT is protection!

malik

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Re: Moteino sleep issues
« Reply #6 on: November 08, 2019, 09:05:09 AM »
Question is, how do we remove corrosion from a RF module, to see if the corrosion is the cause of higher current.

Felix

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Re: Moteino sleep issues
« Reply #7 on: November 08, 2019, 09:24:02 AM »
Ultrasonic cleaning.

malik

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Re: Moteino sleep issues
« Reply #8 on: November 08, 2019, 09:35:58 AM »
« Last Edit: November 08, 2019, 09:42:39 AM by malik »

Felix

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Re: Moteino sleep issues
« Reply #9 on: November 08, 2019, 09:46:23 AM »
Yes I suggest watching some YT videos on how to do it. Various phone repair shops shows this done on smartphone mother boards, to get corrosion and water damage off, or just cleaning flux after repairs.