I’m experimenting with a factory Dell J1KND battery. A quick test with a resistor between pins 6 and 1 confirmed the guess- battery voltage appears on the positive terminals. Measuring the pin to ground resistance in and out of system we see that the laptop pulls pin 6 to ground when battery is inserted. Well, we still have pins 6 and 7 to figure out. It then occurs to me that some batteries have a signal called System Present, and only allow charging/discharging if they see that signal. Something else is going on- time to check if we are missing anything. At the same time, I can plug into the laptop and it stays powered. Once the laptop’s charge indicator goes from yellow to green and power supply current drops, we can start the tests.įirst check is battery voltage and once again it is 0V. Voltage check confirms that- we are now at 11V and rising, meaning the fast charge constant current phase is on, and the battery is finally charging. That may be a good sign- battery is now taking current. Leaving things alone for a bit and checking back in a few hours, the power supply current went up drastically from about 0.5A at 19V to 1.5A.
#Asus n53sv schematic series
That seems to indicate it is alive, but too discharged to allow for charging- most likely staying in precharge mode with a large series resistor limiting input current to very low values. Ok we’ve just confirmed 3 and 4 are indeed the SMbus pins and the battery is talking to the charger. And pin 3 definitely looks like an I2C clock, pulsing nonstop during the comm intervals, while pin 4 looks like an I2C data. Poking around with a scope, we can see activity on pins 3 and 4. Voltage on the pins is now 12.6V, meaning the charger is trying to do its job but no current is actually making it in. With the laptop powered by a bench power supply, we can see a notable surrent spike when battery is inserted, so something does happen. Plan B- put the battery back in laptop and observe signals on the pin. We apply normal for it voltage (in the range of 3-4.2V per cell) and see if it “takes”any current. Next step is to try waking the battery up. Pins 6 and 7 remain mystery for now and pins 8 and 9 are the battery positive. That most likely means we have SMbus (a typical comm channel for notebook batteries) on pins 3 and 4, and a battery temperature on pin 5. Pin 5 has a single channel TVS/Diode looking thing. The next two pins (3,4) are routed through a SOT23 device that measures as a dual diode- most likely a dual Zener/TVS for ESD protection of comm lines. It is pretty obvious that the larger blades are power and ground, and by measuring resistance to case ground we can tell that the leftmost two pins are ground.
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