I need help with dell precision m4800 that dont detect battery. i try all the trobleshooting change battery,do hard reset , everything i know not work.it only power with the adapter and the charging led will be blinking orange light fast please some one here should help on how to fix this problem.
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Re: Dell precision m4800 not detecting battery
Measure the voltage to ground of each pin of the battery connector. Post the measurements. -
Re: Dell precision m4800 not detecting battery
These measurements look ok. We are checking if the smbus lines are stuck or not. You have ~3v on the lines so they are not stuck.
Next, you will need to attach the battery and measure the voltage to ground of these pins again.
Are you able to take the logic board out of the enclosure for more measurements?
We need to check some readings of the charger IC.
Does this laptop function ok with only the power adapter? Does the bios report the correct power rating of the power adapter?
If you boot into windows, does the laptop show the battery graphics?Comment
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Re: Dell precision m4800 not detecting battery
Does the laptop ever complain about 'unknown power adapter ' ?
Are you able to take voltage measurements of the battery connector with the battery connected? Then we can check the battery present pin voltage.
Has this laptop ever been exposed to liquid damage? Just stopped working with the battery one day?
Is the battery with enough of a charge at this time to be able to power the logic board?Comment
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Re: Dell precision m4800 not detecting battery
Not at my computer but need to review the charger IC. This charger IC will have local mosfets that act like switches to enable or disable the use of the battery if the adapter is missing.
The charger IC monitors the battery status and also will charge the battery if the adapter is suitable with enough power. The batteries must be known good batteries.
Do check the battery contacts.
Which charger IC is onboard? Is it the usual BQ series? Share the topside markings of this charger IC. Will check the same once at my desk.Comment
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Re: Dell precision m4800 not detecting battery
1) The schematic for this logic board is posted here:
https://www.badcaps.net/forum/showth...ighlight=M4800
2) See attached. Remove the battery and power up with only the power adapter.
Measure the voltage to ground of pin # 5 = PBAT_PRES# pin.
This pin has a local pull-up resistor @ PR2. Without the battery, this voltage to ground should be ~3 volts.
With battery connected, PBAT_PRES# = 0 volts.
Without battery connected, PBAT_PRES# = ~3 volts.
Confirm it.
3) Charger IC is @ PU700 = BQ24737RGRRAttached FilesComment
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Re: Dell precision m4800 not detecting battery
These are good readings. Is the battery the original? Can you test with another known good battery?
What is the history of this laptop?Comment
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Re: Dell precision m4800 not detecting battery
the battery is original that come with the laptop and i also get a new different battery from different store still not working.
the problem is battery not detected with X mark shown on the battery graphic.Comment
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Re: Dell precision m4800 not detecting battery
Remove all power. Meter in resistance mode.
Check the resistance of the resistor network at PR3.
One meter probe on pin #3 of the battery connector. Other meter probe to pbat_smbclk. Reading should be ~100 ohms.
Repeat for pbat_smbdat line.
Post your measurements.Comment
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Re: Dell precision m4800 not detecting battery
See attached.
Use the meter probes across the resistor network with the RED arrows.
Then repeat the same test with the probes at the YELLOW arrows.
Each should return a value of ~100 ohms. We are only checking to be sure that PR3 resistor network is ok.Attached FilesComment
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Re: Dell precision m4800 not detecting battery
These are very high readings.
The resistance should be ~100 ohms for each check, not in the Kohms.
Can you short your meter probes and post the measurement?Comment
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