I’m trying to design a battery protection circuit for this 300mAh 3.7V LiPo battery.
I’m an EE student which is designing his first pcb. Please forgive questions with obvious answers.
The seller specifies a battery protection circuit is already present. Should I trust it or I’d be better off providing my own?
The rating of the battery is 0.5C for average discharge current, 1C peak discharge current and 300 mAh. From what I understood, that is a really low rating for LiPO batteries and is not consistent with the 4 to 6 A current limiting protection which they state.
The IC which I would intend to use is TI BQ297x. The design suggested on its datasheet is typical, with 2 FETs to manage charging and discharging. The FETs should be chosen according to their
rds. However, the overdischarge voltage threshold of the IC can vary from 90 mV to 200 mV in 5 mV steps and with a max current of 300 mA that would require
2rds = 300 mOhm, that is a quite high. Should I modify the suggested design to meet such a low current? Would it be a good idea to place a resistor between the 2k2 resistor and the FET to increase the voltage drop and avoid high
I understand that Chinese sellers are not a reliable source of information. However, I was not able to find any LiPO battery from online stores like Digikey, Mouser and so on. Where do you guys recommend to buy to be sure about the product listed?
150 mA would be more than enough for my application. I’ll try to find a better alternative to BQ297x. My final design needs to be as small as possibile because it has to be a smartwatch for health monitoring. I think a ready made protection circuit is not a good way to optimize space. Same holds for old Nokia batteries with integrated protection circuits, I fear.