In Cheap and Good? -series we test the cheapest accessories we can find from the Internet.
The first installment is about a replacement battery for Fuji X100 series camera, made by Seiwei.
Original NP-95 batteries for Fuji cameras are quite expensive, here in Finland the price is about 50 Euros. Fuji cameras really need a backup battery or two, so it is tempting to search for cheap alternatives on the net. After a quick search, I found a great deal; two batteries for 9 Euros. Too good to be true ?
The batteries arrived and the visual appearance was quite good, considering the price. The rated capacity on the label was a whopping 2100mAh, over 15% increase to the original battery with 1800mAh . The batteries seemed to work just fine in camera use, so the first impression was very positive. I did feel like the batteries seemed to get empty quite soon after losing one battery bar. However, Fuji’s battery monitoring is not very reliable even with original batteries, so perhaps that was the reason.
To really know whether these batteries were as awesome as promised, a deeper investigation was made. The quickest way to know about battery quality is to measure its’ impedance. 1kHz impedance is a battery industry standard measurement and it gives a good overview on the quality of cell, the protective electronics and the interconnections. Typical result for a good lithium battery used in small devices is 80-100mΩ. My original Fuji battery impedance was 90mΩ. The two Seiwei battery impedances were 148mΩ and 151mΩ. Ouch. In practice this means that the average voltage level is lower, and the voltage drops are more severe during high current peaks like using camera flash. The result is a quicker shutdown. I guess Fuji’s battery monitor worked properly after all.
The real capacity of the battery was also tested. Two discharge currents were used, indicated relative to battery nominal capacity of 2100mAh (0.2C = 0.2 * 2100 = 420mA, 0.5C = 0.5 * 2100 = 1050mA). The results were less than stellar.
As can be seen from the graph, the promised capacity was not achieved. Not even close, even though a test was performed with quite small currents. No wonder the batteries were so cheap. I carefully disassembled one of the batteries, and I was pleased to see that there were some protection components and a temperature sensor. An accidental short-circuit of the battery while in the camera bag could be fatal without any protection. However, the overall quality of workmanship was not of highest standard. After seeing the test results and the innards, I wouldn’t dare to leave this battery alone in a charger.
In conclusion, the batteries were cheap and they do work, kind of. The capacity was very poor and together with high impedance the battery life is very short and you may experience unexpected shutdown in burst mode or when using flash. In camera use, you want a reliable and safe battery in all conditions, and Seiwei batteries do not fit the bill. Better save your money for an original spare battery.
Buying cheap batteries is always a gamble, both from safety and performance point of view. Remember this when looking for great battery deals!