Hallo,
Ive seen some project about disassemble and reinvet the use of AirTags and similar devices. I was thinking about insert one in my laptop since Ive some space.
1. ANDROID USER
Ive got Samsung S20 phone WITHOUT any google or samsung account (in future > LineageOS).
Which tag should I buy?

2. CONNECTION
Since Tags batteries are lithium 3.3V as CMOS motherboard pc battery, should be totally flawless process to connect directly (no fuse no diodes nothing) to CMOS terminal battery socket.

Thanks in advance

 

Laptop POWER batteries are seldom 3.3 volts. The memory battery is important enough that I suggest not messing with it.

 

The only risk I see if I dont power laptop for 2 years and CMOS battery get discharged.
Ok so I can take 3.3V from other sources, right? I will install a CR2032 rechargeable to the Tag and then parallel to a 3.3V motherboard source. Alternatively I can use a 5V source like USB to feed a Vreg to 3.3V.
Im very good at electronics and no problem at all to make a L7833 (3.3V reg) board (w caps and rev diode).

I wait more expert and brave DIYer. thanks

 

As tracker, ppl suggested this brand https://mili-shop.com/products/mili...with-key-ring-work-with-google-find-my-device , in particular this device. Android only but it's ok.
Since will be permanently inside my pc I want something reliable.
4x 36€ amazon it
1x 10€ aliexpress com


Said that, I wont see any problem about my circuit mod.
5v > L7833 (caps and diode) > 3.3V ML2032 exept the fact that it likes 20mAh charge current. Also they are expensive.
So Im looking for alternatives, small ones

LIFEPO4
On aliexpress I can find AAA LFP (will be reliable?) and relative BMS 1S

LI ION
I think again AAA will be the best form factor. 1S BMS

LIPO
Here the puch form factor let me chose between a lot of models. But the same factor could be the most dangerous.

All of these (BMS) can be recharged with USB 5V (that I will take from USB)
HERE THE SCHEME

 

AI suggested me 14500 lifepo4 + bms since they handle high temperature better and safer. What do you think?

 

I see the tracker device would be in a compartment made for some unused add-on. Probably there is power available at that connector. So you could add a charging circuit fed from that connector.

 

The CR2032 is a primary lithium cell and so has a terminal voltage of 3V, not the same as the nominal voltage of a secondary lithium cell with is generally 3.7V or the 3.65V of a LiFePO₄ cell, or 3.3V. While the tag might tolerate the overvoltage, I wouldn't assume that it will.

 

I see the tracker device would be in a compartment made for some unused add-on. Probably there is power available at that connector. So you could add a charging circuit fed from that connector.

There is Ssd slot there to the end of the ribbon connector. The space is small. Im not afraid to solder to usb pins.

 

The CR2032 is a primary lithium cell and so has a terminal voltage of 3V, not the same as the nominal voltage of a secondary lithium cell with is generally 3.7V or the 3.65V of a LiFePO₄ cell, or 3.3V. While the tag might tolerate the overvoltage, I wouldn't assume that it will.

Nice point but OBV I will put a Vreg like LM317 if L7833 is not suitable for. Alternatively a 1n400x diode would Vdrop 600mV so... BUT The tracker I linked says
Battery

• Battery Hours: 6-8 Months
• Charging Time: not support charging
• Battery Type: lithium_manganese_dioxide
• Voltage: 2.6v~3.6v
• Power Consumption: 9.5mA max @adv, 22uA avg @paired
  
  
  
  perfect for LiFePO4 that maximum reaches 3.65V while charging and 2,5V discharge max ( https://it.aliexpress.com/item/1005...8zzwqZ6b&utparam-url=scene:search|query_from: )

 

Don't really see an issue with that plan. As already noted, id be really sure of the voltage situation with the tag and physical damage. Don't get a battery that you have to force the laptop cover closed. Id recommend some of that foam double sided tape to hold things in place. And as far as BMS there are some very good pre-engineered modules so you don't have to do the designing yourself. I'm a fan of adafruit and sparkfun for those, but the aliexpress ones do just fine. I wouldn't get hung up on the thermal issue as far as battery chemistry. the area you point at is far away from the heat making stuff from what I can see.
And if you really want to go on the cheap, rip apart a disposable vape. battery management and battery cell right there. no specing out of parts required. Granted those are designed to a price point, but it will let you see about spacing and voltages without having to buy anything.