Addendum (21.6.2012): This review is from a Weiss LP-E6, which was still entitled at that time with 1800 mAh. The batteries work the way (after about 1 1/2 years) still properly. Here the (otherwise unchanged) Review:
I ordered three batteries and they work in my 5D Mark II with battery handle almost flawlessly, the registry works etc.. Sometimes one does not recognize the battery pack, then I take it out, put it back in and then it's mostly.
As electrical engineer course I was interested in the actual capacity of the battery, I then measured with a borrowed ALC 8500 Expert. Short: None of my three battery has reached the specified 1800 mAh in approach.
Loaded I first with the original Canon charger, discharged at 650 mA and a final discharge voltage of 6.2 V. Two of the batteries had after a few charging cycles about 1500 to 1525 mAh, the third about 100 mAh less. My original Canon LP-E6 battery came under the same test conditions at 1750 mAh. The Weiss batteries have a typical discharge curve, the tension remains until shortly before the end of more than 7.1 V and then bends quickly, while the voltage on my Canon battery after the häfte of discharge under 7.1 V and almost linearly up to 6 , 2 V falls.
The Canon battery charger has, however, not fully charged, by charging the battery with the use ALC 8500 (charger / discharger) I came with my best white battery to a capacity of 1575 mAh (50 mAh more than the Canon charger).
Self-discharge, loss of capacity over many charging cycles and behavior at low temperatures, I have not been thoroughly tested; a battery of about 1 week had lying around 2-3% of its cargo lost, which I think is a good value.
On the whole I am satisfied with the battery so far very satisfied; Weiss would specify the capacity of 1550 mAh, I would have awarded 5 stars clearly. Ansmann reveals honest information here.
PS: Another tip for hobbyists: In order to connect the battery to the universal charger, I Entlöttlitze pulled slightly wider and then tinned with solder. This fits in well then the two contacts, the two ends I then fixed on a small plate with hot glue, so that I can easily put the battery on the board and slide it into the solder tinned.
Addendum (23.6.2011): Due to a post in the DSLR forum, I would like to point out a fact: Since the discharge curve of the Weiss batteries not as linear runs when Canon battery, camera, but the remaining capacity probably determined by the open-circuit voltage, it can happen at the Weiss batteries that they keep very well until shortly after reaching the 30% mark but already empty are. This is by no means a defect in the batteries, the camera is simply set to the discharge curve of Canon batteries and therefore can not correctly determine the remaining capacity of the Weiss batteries.
Practically, this means: If a white battery for 700 photos taken 30% charge status is still displayed, must not assume that about 300 pictures can be made one. Although this would be mathematically correct, but the battery is then as good as empty.