BMS laptop battery, fuse link blown ?

[zioricci]

Hi everyone,

I replaced the cells of a Toshiba satellite battery that was almost 100% charged but the voltage was 0V at the ends of the connector.

I tried to reset the BMS by short-circuiting the positive pole of the battery pack with the positive pole of the connector but without success.

In the meantime I bought a new battery but looking at the battery pcb, I found this fuse


https://ibb.co/Hqfw35L
https://ibb.co/mCP4LT9

resting on a mosfet probably as a protection against overheating. I found this fuse resting on a mosfet probably as a protection against overheating. As can be seen from the photo, internally only one leg is connected to the control unit, does this mean that there has been an excessive current absorption phenomenon and therefore overheating ? The mosfets are still good.

If I put a drop of tin to rejoin the leg to the central unit, would there be hope of recovering the battery or is there a risk that the phenomenon would reoccur ?

Thx

[Vesko356]

Re: BMS laptop battery, fuse link blown ?

You have no idea what it's all about. It's better not to get involved in things you don't understand at all - it's not as simple as you think. You don't have the knowledge (even basic) or the tools to perform a laptop battery pack cells replacement.

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[zioricci]

Re: BMS laptop battery, fuse link blown ?

You have no idea what it's all about. It's better not to get involved in things you don't understand at all - it's not as simple as you think. You don't have the knowledge (even basic) or the tools to perform a laptop battery pack cells replacement.

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I am realizing that communicating in written form is not enough to convey what a person really knows. It's not clear to me what makes it clear that I don't have the basic knowledge. Can you explain ? Thank you.

[Vesko356]

Re: BMS laptop battery, fuse link blown ?

I am realizing that communicating in written form is not enough to convey what a person really knows. It's not clear to me what makes it clear that I don't have the basic knowledge. Can you explain ? Thank you.

Yes I can explain - since you tried to replace the cells and expecting the battery to operating as it should means you have no basic knowledge on the matter. Also your questions about the fuse means also lack of basic knowledge. In 90% of the cases after this procedure (cells replacement) the controller sets a permanent flag and lock the battery, but bearing in mind the fact that the fuse has blown means that it's 100% locked (the controller itself sends a signal to the thermo-controlled fuse which cuts the power line, simultaneously setting a permanent flag). The very fact that you're trying to "reset the BMS" by "short-circuiting the positive pole of the battery pack with the positive pole of the connector" means lack of basic knowledge (just don't show me YouTube videos where this procedure is shown please). The controller must be unsealed and in FAS mode (SEALED meaning that it’s password-protected so no actions can be done until the chip is UNSEALED, and in Full Access Mode), after unsealing the permanent flags (PF Status) must be cleared (PF Status = 0000) to make the battery operable again, this can be done by the special tool for the purpose only. For example NLBA1 battery tool. Not to mention that after battery cells replacement the chip must be reprogrammed too (EV2300 adapter and BqEvsw software for example if it's TI controller) and afterwards calibrated, and so on.

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[zioricci]

Re: BMS laptop battery, fuse link blown ?

Yes I can explain -...........

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Thanks for the reply.

Perhaps we don't understand each other but for me the basic knowledge in the electronics sector is Ohm's laws, Kirchooff's principles, operational amplifiers etc... I know these very well both theoretically and practically because I studied them at the University, but for fun and necessity I am a technician myself, even if I know very well that I can't have the experience of a professional technician.

So I don't have all the technical skills on laptop batteries, except in its general operating principles, and I didn't know that component was a fuse even if I know the purpose of a fuse well. The university can't provide all the skills, otherwise I wouldn't have asked here.

I just took the whole cell pack off a compatible battery and connected it to the original battery pcb, hoping it would work but it didn't and hence the discovery of that fuse and hence my question.

Edit:
I forgot, tomorrow I will receive a new battery and even if I wanted to try to restore the contact inside the fuse, I would have done it just out of curiosity, with all the necessary precautions, of course.

[harp]

Re: BMS laptop battery, fuse link blown ?

Inside this fuse is internal heater element, about 10R-50R, which is driving by transistor. If you do to jumping fuse, be shure to monitor if transistor get signal to cutoff power - if so, disconnect bms from battery. The Vesko was rude, it can be say in other way...

[mcplslg123]

Re: BMS laptop battery, fuse link blown ?

Dont take it personal-these are opinion by professional in the field. So take it in postively and set yourself to upgrade skills.Later comments by @vesko were asked by OP and he just said you should'nt proceed as you dont have necessary tools/skills etc etc. So i dont see anyone being rude here.