[WheresWaldo]

Two additional batteries tested. These particular batteries were eBay listed as 1750mAh but in actuality they were clearly marked 1400mAh. Just an FYI, standard Minolta batteries are also 1400mAh.

File Date

View Picture EXIF

You will notice that these are rated at 1400mAh or about 86% capacity of the OEM Pentax batteries. At about $7.50 per battery that should be a bargain. These batteries weigh a few grams less than the Pentax batteries at approximately 73 grams each.

Using the CBA II I ran both batteries through three cycles to make sure there wasn't an issue with the batteries themselves. These cycles were done at a 1C (1400mAh) discharge rate to ensure that there were no issues with the individual batteries.

These Chinese batteries were tested with the following parameters:

Battery Type > LiIon
Battery Capacity > 1.4
Battery Voltage > 7.4
Battery Cells > 2
Test Type>Discharge
Cutoff Voltage > 6.0
Discharge Current > 0.5

The Pentax battery was not retested for this round.

To remind everyone I choose a discharge current of .5 Amps as this is what I suspect the average drain from a mix of screw drive auto focus use and internal flash use might average out to and to keep in line with best practice when I tested AA and AAA batteries in the past.

I performed each discharge test about 10 minutes after pulling the batteries off the Pentax D-BC50 charger. The 1400mAh Chinese batteries were consistent and had a power curve very similar to the 1800mAh and 2000mAh batteries tested previously. The voltage sustainable under load was just a bit less than that of the Pentax OEM battery but not enough to affect camera operation. The consistent readings does indicate that there is some quality control built into the manufacture of these batteries. These batteries were so close that only 1mAh separated them. If I was looking to match a set of batteries this is well within the range that I would call identical performance. Again let me remind everyone that stated capacities are usually measured at a percentage of the total rated output. That measurement is usually .2C or 20% of the rated capacity, so in order to see a reading of 1400mAh I would need to test them at .28 A not the .5 A that I did. Because of this we should expect the numbers to be lower. In nearly all the tests I got about 1300mAh readings. During the final test, as listed above, 1331mAh and 1332mAh were the actual capacities from these batteries. Performance was 95% of rated capacity, within a margin of testing error. By comparison the OEM Pentax, rated 14% higher, actually output 1552mAh at the same current draw also 95% of their rated output.



Are these Chinese battery worth the cost? Well these two batteries cost me $15.10 shipped from Hong Kong. The Pentax battery is currently available from B&H for 46.95 + shipping.

Bottom line: Each Chinese 1400mAh battery 14% less capacity and only 15% of the cost, you decide.

In a few months I will revisit all three pairs of batteries to see how they are holding up to use.

Attached Images

1400mAh.pdf (49.0 KB, 445 views)

---

Last edited by WheresWaldo; 01-09-2009 at 07:15 AM. Reason: Small spelling and grammar corrections

[dazman]

Once again, great test report/review. Your efforts are appreciated. Thanks