Laptop battery charging circuit

[Onabit]

Re: Laptop battery charging circuit

Thank You for this informative thread

Pls the charging IC bq736 hidrv and lowdrv give 1.3v
I don't understand is it correct or it suppose to be 3v... The system am working on is hp 640

[Liken]

Re: Laptop battery charging circuit

A question.

If laptop battery BMS is locked (there is not output voltage), and you bridge, force, output voltage (I know, it is not recommended and it is dangerous, this a theoretical question), would the laptop charge the battery?

Or put another way. If the battery BMS, through communications, tells the laptop that it is locked, would the laptop enable voltage for charging?

[Vesko356]

Re: Laptop battery charging circuit

A question.

If laptop battery BMS is locked (there is not output voltage), and you bridge, force, output voltage (I know, it is not recommended and it is dangerous, this a theoretical question), would the laptop charge the battery?

Or put another way. If the battery BMS, through communications, tells the laptop that it is locked, would the laptop enable voltage for charging?

No.

.

[Liken]

Re: Laptop battery charging circuit

No.

.

OK.

It's just that I was thinking what would happen if you had a battery with a locked BMS or with a blown fuse, and, instead of bridging it, you put a regular 4S BMS (without comms) in parallel with the original. So the laptop communicates status with the original BMS while receiving power through the parallel BMS. But I understand that most, if not all, will refuse to enable charging.

[cyngo]

Re: Laptop battery charging circuit

How is this charging process related to EC / KBC? I think they keep communicating so they can charge. for example on the SMB0_DAT & SMB0_CLK pins in the battery socket, where these pins are connected directly to the KBC. There are times when the pin drops because of the KBC so the charging process doesn't occur, there are also times when you need to flash the KBC or replace the KBC so that the charging process occurs.

[M Ramdhan Qurrota A'yun]

What is the solution if the voltage on the + battery pin is 19volts, but the battery is not installed?

[mon2]

This will probably be that the high side battery charge MOSFET is defective. The high side and low side mosfets switch on/off to lower the main power rail voltage to charge the battery. Remove all power. Meter in resistance mode. Test the resistance across the MOSFET pins:

Source / drain
Source / gate
Gate / drain

Each resistance must be hundreds of k ohms or higher else the mosfet is defective.

[wk kim]

Thank you

[Sametbey]

Voltages measured on a working notebook may be helpful.

[saveelektro]

Thank you so much for this great post, i'm starting to love this forum