Dell inspiron 17r 7720 don't work on battery

[rbvndonh]

Hello,

I have Dell inspiron 17r 7720 with work on battery problem.
Motherboard:
DA0R09MB6H1

In bios there is:
AC adapter 180W visible.
Battery work normal condition information.
In windows it shows 100% charged battery and 41% health (it is greencell replacement battery).
It had replaced by someone power supply cable.

I've cheched PQ1, PQ2, PQ31, PQ32. I believed PQ34 will be bad, but there also isn' short.

Basing on that i replaced BQ24707A for new one, but nothing changed.
PR3, PR4, PR5, PR6 have OK values as in schematics.
I found that PR132 have 150ohm instead of 240ohm which shall be still OK for PQ1, but maybe for PQ3 generates problem?

Have you any hints what to check?

[mon2]

Re: Dell inspiron 17r 7720 don't work on battery

Measure the voltage to ground of pq34 (battery mosfet).

Source (1-2-3)
Gate (4)
Drain (5-6-7-8)

Measure with adapter and battery connected.

Then measure again with battery only.

The soldering of the charger IC is ok?

[rbvndonh]

Re: Dell inspiron 17r 7720 don't work on battery

D 1,065V
G19,5V
S19,5V

D 2V quite quick going down to 0V
G0V
S 2V goin slower down to 0,5V

IC is soldered properly.

[mon2]

Re: Dell inspiron 17r 7720 don't work on battery

Update - revising this post.

D 1,065V
G19,5V
S19,5V

These are good readings for the P-channel mosfet (PQ34).

When gate is 19v5, the mosfet is OFF so the drain pin = battery voltage.

When the GATE voltage is lower, then the mosfet is ON.

Are you able to charge the battery pack with perhaps another machine?

[rbvndonh]

Re: Dell inspiron 17r 7720 don't work on battery

SD - 4,6Kohm
SG - 21Kohm and rising
GD - 600Kohm and rising

NPN require i.e. 25V gate to switch on tranzistor, but here PNP require lower gate voltage to switch on. However there is 19,5V and it switch, but shouldn't. I am right?

On monday i shall have access to Dell E6540. It looks like the same battery.

[mon2]

Re: Dell inspiron 17r 7720 don't work on battery

No, please see my revised post. From your measurements, the mosfet appears to be working correctly.

With the high gate voltage, the mosfet is OFF. The drain pin = battery voltage = 1,065v. Battery is depleted.

When the battery only is used, the mosfet gate voltage = 0v to enable this mosfet but the battery is depleted.

When the battery & adapter are connected, you should have a charge voltage to charge this target battery @ PL6 coil.

Confirm the voltage on each pin of high side charging mosfet @ PQ33.

[rbvndonh]

Re: Dell inspiron 17r 7720 don't work on battery

Adapter only
D 19,5V,
G 1,06V
S 1,06V

With battery same readings.

[mon2]

Re: Dell inspiron 17r 7720 don't work on battery

PQ31 and PQ33 are N-channel mosfets so for these to turn ON, the gate voltage must be higher than the voltage being passed through source / drain pins.

So the gate voltage must be higher than 19 volts to enable (often ~25 volts).

At this time, the high side mosfet is DISABLED and the voltage readings are correct.

Now attach the battery AND the adapter to see if these voltage readings change or not.

[rbvndonh]

Re: Dell inspiron 17r 7720 don't work on battery

Yes, with battery and adapter still on PQ33:
D 19,5V,
G 1,06V
S 1,06V

Strange, that battery communicates fully charged, in bios show normal operation and in batteryinfoview shows 41% health (same in Dell diagnostics). It seems as it talk with battery.

[mon2]

Re: Dell inspiron 17r 7720 don't work on battery

Carefully, measure the voltage to ground of the REGN pin # 16 on the charger IC (PU8).

This is the LDO voltage that should be ~6 volts on this pin.

Next, remove all power -> measure the resistance (like before) but on PQ33.

Post each resistance measurement of this high side mosfet.

[rbvndonh]

Re: Dell inspiron 17r 7720 don't work on battery

PQ33:
SD 21Mohm and rising
SG 204Kohm
GD 24Mohm and rising

I didn't found for now any shorted tranzistor

With adapter only and adapter and battery
PU8
pin16 6.1V

Only battery pin16 is 0V.

I checked on ESD2
1. 3,3V so PS_ID shall be OK
3. 3V adapter only, -0,03V adapter and battery, 0V with battery only
4,5,6. adapter and battery 3.3V. Battery only 0V.

If there is smbdat and ambdclk is 3.3V then it is ok and ITE shall be OK?

I checked plenty of different topics, and EC capacitors close to battery are not shorted, however didn't checked capacity.

Maybe at real battery is damaged..

[mon2]

Re: Dell inspiron 17r 7720 don't work on battery

Based on the voltage measurements of PQ33 in post #7, the high side mosfet is not enabled. This may be due to the PQ33 being defective or the charger IC is unable to boost the required voltage for the gate pin.

Remove all power. Meter in DIODE mode.

Red meter probe, yes red to ground.
Black meter probe to PQ33 pin # 4 (gate).

What is the diode mode reading of this pin ?

Being an N-channel mosfet, the gate voltage is expected to be > 19 volts (adapter voltage) to enable this mosfet.

[rbvndonh]

Re: Dell inspiron 17r 7720 don't work on battery

Thank you for support. On battery from E6540 it is working without problem, so the main reason was battery itself.
Old power supply socket with cable was damaged and also old power adapter id pin was damaged. Maybe there was some shortage, which didn't caus any other damage.
That could be a main reaseon, that battery controller locked it.
It was very strange, as battery was visible, fully charged and 41% life, but was anyway locked.

[mon2]

Re: Dell inspiron 17r 7720 don't work on battery

That is what was asked in post #4. Sounds like that the battery is incompatible with this model of the laptop if the same battery is working inside another unit.

[rbvndonh]

Re: Dell inspiron 17r 7720 don't work on battery

With smaller, dedicated battery all works fine.
Thank you for help.
I shall somehow lock the topic? I dont see such option