4650mAH become 5000mAH?

Yesterday I received a Dell D620 battery to realt, from one of our India friend. The battery fail, because one segment of battery seem to have internally disconnected due to it operated exceed the safety boundary.



The battery is label 11.1V 56WHr. Which is a total of 5200mAH LG cells inside. But since I only have 4800mAH (which normally perform in range 4650-4750mAH for the others notebook), so I put in the labeled 4800mAH cells.

Some of Dell battery, allow a maximum of 13.3V charging voltage, which is 4.43V per cell. Although manufacturer claim that cell are allow to be charged at maximum of 4.5V. But generally, to keep the things safe, it is undesired to pushing the limit. In fact, most battery charger limit the charging voltage to 4.2V per cell.

Although the maximum charging voltage is 13.3V, but it don't charge up to 13.3V okay. At approx 13V, the battery will enter pulse charge mode. Dell battery is always using pulse charge mode, so the battery is allow to be fully charged faster at the nearly end of charging (example, last 10% can use up to 1hour if using constant Voltage limiter charge method, you probably only need half an hour to charge it to 100% with ExpressCharge(TM of Dell) system).

So the battery end of charge at 13V, which is 4.33V per cell. Compare to those stop charge at 4.2V, I found something interesting, the cell get a few hundreds mAH (approx 400mAH) extra for the 0.13V extra.

LG(Korea) 2600mAH cells in original battery pack, I thought LG 2600mAH is orange color.