Replacing 2 x AAA to LiPo in Bluetooth mouse.

[3dgeo]

Hello,

Mouse PCB pictures bellow (got to love electrolytic CAP factory mod, and yes, apart from a few pubes that got caught over time PCB came from Gigabyte factory looking like this).

My plan was to replace 2 AAA batteries (2.5V) with  Lipo (2.9-4.2V) and low voltage step down converter, but when I inspected the board I found USB VCC, USB DP (guessing Data Positive) and DM (Data Minus?) , it does not have USB port, those traces goes straight to IS1616 IC, so
I can assume that this chip is 5V tolerant? Battery wire goes straight fo that chip aswel, but battery and USB VCC are not connected together.
I can't find any info on BT module apart HT24LC08 – it's CMOS 8K 2-Wire Serial EEPROM, operating voltage: 2.2V~5.5V.
Is it safe to assume this module 5V capable? YOLO it and connect 5V directly to battery wires?     Would be great if I can just plug directly LiPo wires to old battery connector....

[3dgeo]

I YOLO it...............

Aaaaand it works  Tho I don't want to push my luck, LiPo will be max 4.2V, not 5V. This mod turned out way easier than I expected...

Cheers 

[nsrmagazin]

Its not safe, but riskable.

This "2 AAA batteries (2.5V)" is "3VDC". It seems your entire circuit is 5V tolerant, but it was powered from less to spare batteries. A "5VDC" USB power supply can be "4.5VDC" actually. It will work most likely, but do it at your own risk as I want to wash my butt!

[wasyoungonce]

Jeez that PCB and soldering is so bad it’s a wonder it works. From Gigabyte.... must be a sub-contractor.  Many of those BT modules are either 5V or 3.3V. The 5V versions usually have their own 3.3 v regulator or use one off module

[NiHaoMike]

I think the USB test points are for the wired or combo wired/wireless version of the mouse.

[3dgeo]

Jeez that PCB and soldering is so bad it’s a wonder it works. From Gigabyte.... must be a sub-contractor.  Many of those BT modules are either 5V or 3.3V. The 5V versions usually have their own 3.3 v regulator or use one off module

Yes, PCB looks bad, it got stains all over it. I found out it's a remake of a cheap very popular mouse in China, it's almost identical electrically, but with different shell. Tho it's very compact and comfy, don't want to trow it away, will be good for my laptop.

If anyone cares I ordered these bateries and will DIY BMS from but without boos circuit. I have TP4056 prebuild boards, but as I found out they connect battery again if it recovers above discharge voltage, "Great scotts" BMS reconnects only when it gets charger impulse.