Measuring cell temperatures while testing?

sunseeker

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Joined
Aug 30, 2017
Messages
16
Hi guys,

did anyone ever came up with a DIY setup to measure the temperature while testing 18650 cells?

Since I'd love to test all thesecells when I am not at home or during my sleep cycles, I am worried that I won't recognize when one cell runs too hot when bulk-charging them initially, right after they came out of the old laptop packs. For the worst case, I would like to disconnect the charger when a cell gets too hot and I am not around.

I played with the idea of chaining a couple of DS18B20 TO-92 Temperature Sensor and hooking them all up to a RasPi. They are one-wire and have an ID, so that one can read them individually although they are all hooked up on one string in series. I thought about building some kind of a clip that I could lay over the bulk-charge cell holder and read from them every 10 secs.

Even with the BT-C3100 I sometimes wonder if it stopped charging due to excessive heat and picked up charging a couple of times without me noticing. When I check the results in the morning, I wouldn't know.

I am also interested in the data.. so temperature curves of different cells etc.

Do you guys think that this could work? Given that it's possible to put these sensors in touch with each unterlying cell.

Thanks!
 

SimonW

Member
Joined
Aug 26, 2017
Messages
89
Definitely do-able, a couple of members here have done similar:

By 'daromer'

Also, Jeremy Choy
http://secondlifestorage.com/t-Show-off-your-DIY-and-modified-tools?pid=11572#pid11572
Though I've been unable to find any further information about Jeremy's

I have a whole heap of Sanyo cells to test so I'm also working on similar but using LM35DZ's and an STM32 rather than Arduino or RasPi.
It's early days, but same basic idea as you, cut the charger if overheated cell while unattended.
 

nilsd

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Aug 31, 2017
Messages
1
I'm gonna putfourDS18B20s on a piece of wood and just let them rest on the cells in the Opus, and send a push to my phone when any of them goes above 50C.

Until I have a safer place to do this ratherthan inside my house I'm gonna be over-careful =)

I just bought a metal box from Ikea where I put my Opus!


image_xybgzy.jpg
 

daromer

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Oct 8, 2016
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5,565
Yeah i did such a visualization. Works with the image I have done too
 

sunseeker

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Aug 30, 2017
Messages
16
Thank you very much guys!
Cool that you have that kind of setup, Dan! I've must missed that video of yours :)

I guess most important to me is to be able to trigger a 240 volt switch when temperatures get too high. Cool that you used Graphite and Grafana, though I guess my idea with keeping track of single specific cells is just too much work in the end.

Cheers,
Heiko
 

daromer

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Oct 8, 2016
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5,565
Yeah the setup is growing for each day :)
Yeah with a Rasp that is easily done. I also have a video on how to controll a SSR relay. Just switch that one out for an arduino relay board and you are good to go.

This whole thing can of course be be done with ESP8266/ESP32, Arduino or any other computer out there :)
 
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