Archive for the ‘NiCd/NiMH Batteries’ Category


The 1.2V AA 1050 mAh GP EkoPower NiMH batteries we test here are the traditional NiMH type (not LSD ones) and are of quite low capacity for a rechargeable battery. The fact that these NiMH batteries are rated at only 1050 mAh makes it clear why that capacity is not written with large letters, but you need to take some time to actually find where it is written. These GP EkoPower batteries are rated at up to 1000 recharge cycles which is still a plus even though they will be offering significantly less capacity than a standard Alkaline battery per charge.


We started the tests of the 1.2V AA 1050 mAh GP EkoPower NiMH batteries with a constant current discharge rate of 0.2A (200 miliampers) and they were able to provide us with just 991 mAh disappointing us a bit as they are supposed to provide 1050 mAh typical capacity. On the other hand the overall low capacity of these batteries may be the reason why the do not handle that well with 0.2A constant current load, it is possible that they will perform better in a low current drain situations. Also going up to 2A constant current load these batteries were clearly not capable of handling such high loads of about twice the battery capacity. So if you have these batteries you should stick to using them only in devices with low power requirements, what we can say is that we were not very satisfied with what we got from the 1.2V AA 1050 mAh GP EkoPower NiMH batteries.

The performance of the 1.2V AA 1050 mAh GP EkoPower NiMH Batteries in our tests:

– 991 mAh at 0.2A load
– 910 mAh at 0.5A load
– 747 mAh at 1.0A load
– 12 mAh at 2.0A load

– 1.205 Wh at 0.2A load
– 1.043 Wh at 0.5A load
– 0.798 Wh at 1.0A load
– 0.012 Wh at 2.0A load


The 8.4V 250 mAh Powerex Imedion NiMH batteries we test here are based on the new LSD NiMH type (low self discharge) and are supposed to retain up to 85% of their capacity after an year of storage unlike traditional NiMHs that discharge at a much faster rate when not being used. The best thing about LSD NiMH batteries is that they are ready to be used immediately after you get them, thanks to the low self discharge, though they are not going to offer their full capacity initially. These particular batteries are supposed to offer up to 1000 recharge cycles according to the manufacturer and though they are rated at 250 mAh they ar also supposed to provide minimum guaranteed 230 mAh capacity according to their specs.


In order to test the capacity of the 8.4V 250 mAh Powerex Imedion NiMH batteries we are using a constant current discharge rate of 0.05A (50 miliampers), but before measuring the real full capacity we measure the capacity available for use right out of the box. In the case of our test battery it was just 119 mAh or about half of the capacity of the battery, however we are not sure how long since it has been produced, though it is most likely more than a year. The 8.4V 250 mAh Powerex Imedion NiMH battery we tested here managed to provide 234 mAh capacity before hitting the 7V cutoff voltage and that is actually a bit over the minimum rating for the battery, though not that close the maximum of 250 mAh. Though in a few more cycles the battery might reach it’s full capacity as we are testing all LSD NiMH batteries after doing only one discharge/charge cycle and traditional NiMHs after a charge/discharge/charge.

The performance of the 8.4V 250 mAh Powerex Imedion NiMH Batteries in our tests:

– 234 mAh at 0.05A load

– 2.034 Wh at 0.05A load

In overall we are getting very good performance for an 8.4V NiMH battery, though some 9V Alkaline (not Carbon Zinc) batteries might be able to provide a bit higher useable capacity don’t forget that here you get a rechargeable battery with up to a 1000 recharge cycles.


The 1.2V AA 3200 mAh Mex Cell NiMH batteries are a clear example of a Chinese manufacturer labeling rechargeable NiMH batteries with higher capacity then they actually are. These batteries are supposed to be 3200 mAh, however they are being sold at a price of NiMHs with half that capacity, so this is supposed to raise some suspicion. So when you see batteries with very high capacity that are suspiciously cheap and from a brand that you’ve never head of, then you should be careful. Anyway, lets us see what is the actual capacity of these batteries and what current they can handle.


The maximum capacity we’ve got from the 1.2V AA 3200 mAh Mex Cell NiMH batteries at the minimum constant discharge rate of 0.2A we are using for testing NiMH batteries was 1486 mAh or more than twice less capacity than the batteries are supposed to provide. The only good thing here is that the batteries are handling pretty well with a current load of up to 1A, but going for 2 amps current draw and the voltage quickly drops below the 1V cutoff that we are using.

The performance of the 1.2V AA 3200 mAh Mex Cell NiMH Batteries in our tests:

– 1486 mAh at 0.2A load
– 1416 mAh at 0.5A load
– 1237 mAh at 1.0A load
– 145 mAh at 2.0A load

– 1.847 Wh at 0.2A load
– 1.700 Wh at 0.5A load
– 1.418 Wh at 1.0A load
– 0.148 Wh at 2.0A load

Definitely not worth buying these batteries as they are not delivering the promised capacity, not even half of it, they are actually something close to 1500 mAh and even though they are cheap, you will most likely get a better quality 1500-1600 mAh batteries for the same price. Be careful with unknown brands promising very high capacity battery at way too attractive price!