When is Actual Capacity and Maximum Capacity valid

[steve6375]

Hi
I have come across some batteries which only last 30 minutes, but the design capacity is 4000 mAh (=3.5hrs), the max capacity is 3200 mAh and when fully discharged and charged, the actual capacity reads 3200.

I thought the battery should show a low capacity if it only lasts 30 mins as the SMART stuff will adjust these figures.

Basically, this seems to imply that I cannot always trust the 'max capacity' reading.

I understand that to have a vaild max capacity reading, the battery should have undergone a complete charge/discharge/charge cycle (to remove any SMART calibration errors caused by partial charge/discharge cycles). But I have done this and I still get a high reading when the battery only lasts for 30 minutes!

How come?

Thanks
Steve

[David (PassMark)]

The short answer is that I don't really know the true reason. I can only speculate.

Our BatteryMon software doesn't attempt to calculate these figures. It gets them from the the charging circuit and device driver in the PC.

The charging circuit and device driver where probably designed with certain battery and battery capacities in mind. They were probably also designed to take into account some limited degradation of the battery. Being of a chemical nature batteries always degrade.

But it sounds like your battery has an outright fault (80% drop in capacity). Which the charging circuit probably doesn't know how to deal with.

But BatteryMon should make this behaviour easier to see, the charge graph, after a few minutes of running, should show a much steeper decline in remaining capacity that one would normally expect.

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David