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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?Comment
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Re: Laptop battery charging circuit
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.Comment
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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.Comment
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What is the solution if the voltage on the + battery pin is 19volts, but the battery is not installed?
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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.Comment
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Thank youComment
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Voltages measured on a working notebook may be helpful.Attached FilesPremium supporters get full download access and other benefits.
I'm not happy to be so strong. because it's not humanlyComment
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Thank you so much for this great post, i'm starting to love this forumComment
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Great explanation. ThxsComment
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This is awesomeComment
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Thank you. It was very helpful.Comment
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Hi,
Recently I wanted to finally tackle recelling my dead HP NX5000 battery pack (3S2P pack) since there aren't any replacements available. Before recelling it was detected as a valid battery and it's charge was always stuck at 50% (although it didn't hold any charge).
Two middle cells had rust on them, the 4 other weren't affected by it. BMS wasn't corroded in any way, was pretty much in prestine condition. Replaced them with some moderately used 3S2P (charged to 11.44V) pack from a lenovo battery.
At first, everything seemed to work. Battery was still detected,...02-03-2026, 09:24 AM -
My question pertains to understanding the control circuity inside a Dell PT434 type battery used in Dell E6400, E6410 and other Dell notebooks?
Does anyone have a circuit diagram for the inside of a Dell PT434 battery and/or a description of how the control lines work to control this battery?
My reason for asking is I have a battery which I cannot get to charge beyond 1% in a Dell E6410 or E6400.
The LED bar graph charge indicator on the battery shows one LED lighted when the info button is pressed.
I have tried multiple different Dell power adapters. My Dell... -
I have a Dell latitude 5590 of unknown history. exterior looks mint/ barely worn but it is completely dead. I am a complete novice in board repair but do have a background in small appliance repairs so not a complete noob, but close. I have done the usual things i know of o try and revive d dead laptop for example opened up the laptop, disconnected the battery, RTC battery and while unplugged form the charger shorted out the battery pins in the RTC BATT connector. and this has not changed anything.
I took out and re seated the RAM modules and no difference.
I took out my multimeter... -
Hi Everyone,
I have brought you a mistery item
This laptop have come with some strange faults.
1. CMOS battery was flat 0v
Symptoms:
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Amp drawing was stuck at 0.005 milliamps.
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After inverstigation RTCD1 diode had a low value... -
Hi badcaps community, Im very begginer guy which transitioning from IT into Tech industry due to finding it more logical in long-term.
Recently had my laptop broken.
Left 220v cord disconnected from power supply for 1hour and cameback - laptop was gone.
Drained bios, laptop started and then shutdown instantly. (battery showed 0%)
It did not turned on again. Checked one last time with unscrewed battery (wanted initially just replace the battery as it had only 50% capacity left.
That was my quick "diagnosing". And it slipped from my hands while...
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