JumpZero
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Lipo battery leak: is it possible?

Sun Jul 09, 2017 11:52 am

Hello,

I have a Seeduino Stalker (It's an arduino like system) http://wiki.seeedstudio.com/wiki/Seeedu ... _Solar_Kit connected to a Raspberry pi by radio nrf24L01+
I monitor the swimming pool temperature
http://gcolin.hd.free.fr/SystemDescript ... /page.html
Everything works fine
But...
3 days ago I noticed condensation under the transparent cover. I thought rain water has come inside. Clear liquid (I though water) was at the bottom of the box. I opened, cleaned and dryed.
But the following morning condensation again.
Plus the system has stopped 11pm same day just after daylight went off and restarted the following morning when daylight was back.
So I think the battery is dead and the liquid was not water but electrolyte. Do you think this is possible?
It seems possible according wikipedia specially the battery is exposed to high temperature: when the sun is there it can reach more than 60°C inside the enclosure. See here http://gcolin.hd.free.fr/Gujan/temperat ... /page.html(live graph)
But these last 2 days the system is up again with no problem....
Ok the question is more related to lipo battery than to Raspberry Pi but there is so much maker knowledge here ;-)
Any experience feedback from anybody?

Thks

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Ronaldlees
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Re: Lipo battery leak: is it possible?

Sun Jul 09, 2017 12:53 pm

"Do not leave lithium-ion batteries in any place exposed to direct sunlight, such as a vehicle dashboard or a window sill, or exposed to high temperatures such as a vehicle parked in the sun. Doing so may cause the lithium-ion battery to leak." - a quote from http://www.baj.or.jp/e/frombaj/03.html (battery association of Japan).

In this situation, I am tempted to use NiMH bats. Well, I almost always use NiMH. Even those should not be left in direct sunlight tho ...
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JumpZero
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Joined: Thu Mar 28, 2013 7:35 pm
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Re: Lipo battery leak: is it possible?

Tue Jul 11, 2017 10:10 am

Thank you,

Good point.
I cannot replace the battery with NiMH because the charger is made for LiPo battery.
BTW it's a kit with solar panel, charger, enclosure and battery, so it's quite annoying the battery cannot withstand temperature due to sun exposure...
Anyway for the next projects I'll choose NiMH.
There si always something good with experience

Thanks
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Jmp0

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Ronaldlees
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Re: Lipo battery leak: is it possible?

Tue Jul 11, 2017 2:56 pm

Even NiMH can leak if they get too hot, but I'm not a battery expert.

IMO - I would be tempted to separate the battery pack enough so that it could be put where it is shaded and cool. This is a good idea no matter what type of batteries are being used. The cabling would have to be such that nobody trips over it, etc. Tripping could be really bad next to a pool! I personally (if it were my project) would want any battery cable somehow placed under the concrete or deck, and secured so that it couldn't be a trip hazard - (personal, unprofessional opinion - and I'm not suggesting the use of cables or anything else - for anyone else).

For these kinds of applications, I like the Photon (particle.io). But, as you say, yours was already in the kit. The Photon can be put into 'sleep' mode, wake up, take a reading, go back to sleep, wake up, etc, etc). When in this mode, it takes almost no power at all to operate for a pretty long time (maybe a month, depending on cycles), and so really low power batteries can be used ...
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JumpZero
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Re: Lipo battery leak: is it possible?

Tue Jul 11, 2017 7:15 pm

Hi
Ronaldlees wrote: I would be tempted to separate the battery pack enough so that it could be put where it is shaded and cool. This is a good idea no matter what type of batteries are being used. The cabling would have to be such that nobody trips over it, etc. Tripping could be really bad next to a pool! I personally (if it were my project) would want any battery cable somehow placed under the concrete or deck, and secured so that it couldn't be a trip hazard - (personal, unprofessional opinion - and I'm not suggesting the use of cables or anything else - for anyone else).
This is exactly what I'm planning to do.
I'll put the new battery under the round plastic cover (see photo) it will not be exposed to sun but in the shade, + cooled by nearby water just under in the skimmer. The only problem it brings is: another opening in the box for the cable, it means it should be watertight, but I can do that (cable gland or epoxy resin or even hot glue).
Image
Ronaldlees wrote:For these kinds of applications, I like the Photon (particle.io). But, as you say, yours was already in the kit. The Photon can be put into 'sleep' mode, wake up, take a reading, go back to sleep, wake up, etc, etc). When in this mode, it takes almost no power at all to operate for a pretty long time (maybe a month, depending on cycles), and so really low power batteries can be used ...
I already do that, the Seeduino Stalker (an arduino compatible) goes to deep sleep with ultra low current consumption and its RTC wake it up every minute, then it reads temperature and send it by radio nrf24L01+. There is 1 year already it's working with 99.9% radio transmission ok. Even during winter when there is only 8 or 9 hours daylight and the weather is cloudy I had enough power in the battery to run 24H. In this graph you can see the battery charge (over 1 year), the lowest was 65% charge.
Image
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Jmp0

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Ronaldlees
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Re: Lipo battery leak: is it possible?

Wed Jul 12, 2017 12:28 am

Looks like a nice project, but if I were you I might be worried about somebody tripping over your sensor control unit. Is it on top of the deck, next to the pool? It seems like it is on top of the tile in the photo ...
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