Has anyone seen one of these?

Always learning

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Jul 28, 2020
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I found this cell inside my eiger under the hood work light.
If you are in UK, these under the hood lights were sold at Homebase, and now and then you still see them on ebay, gumtree etc. These eiger lights are very similar, if not the same, under the name "Braun" in USA.
I will upload a pic of the cell that came inside this eiger light as I never seen one 18650 cell with the same reference, so other users can have a look.

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It looks to be an 18650 with a protection circuit - quite a common configuration in devices powered by Li-ion batteries.
 
gauss163 said:
It looks to be an 18650 with a protection circuit - quite a common configuration in devices powered by Li-ion batteries.
Yes, it has written on the side TNL-ITR 18650 3.7V 2000mAh
 
Yup, quite common. It's a 1S1P simple BMS, basically. It protects over/under-voltage. Obviously no balancing circuitry. The IC's are possibly the DW01 chips as they are very cheap (these are the ones on the TP4056 w/ protection circuitry)
 
^^^ Single-cell protection circuits mustdo more than simply protect against extremevoltages(OVP/UVP). They also protect against overcurrent (OCP)and may also need to permanently disableextremely overdischarged cells (0V inhibition), e.g. see the datasheet for the Seiko S-8261, a common protection IC used on protected 18650s.

It is important to keep in mind that generally such protection circuits are less safe than completely integrated systems such as in a laptop- which e.g. include multiple levels of redundant protection, as is explained here.
 
Thanks guys for the comments.
As I said above, I also have a laptop battery to open up and take the cells out. Do you recommend any YouTube video that you guys think it shows the most appropriate way to take the cellsout of its casingand test them? I have been watching a few videos already but probably some of you also know other videos that I didn't come across yet.
I'm about to order aLiitoKala Lii-500 4 Slots Smart Intelligent Battery Charger.
 
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