The charger does not charge the batteries one by one. 2 or 4. The problem is that it does not charge them fully. If one is empty and the other is halfway, it will charge until one is full and the other will remain halfway. I bought a much more expensive charger from Panasonic that shows the volts. After I had charged 4 together with the Varta one, I put them in the other and there were 2 half-charged and 2 empty. The batteries are great. Just stay away from the charger.

The product comes with 3 charging cables (plug, car adapter, and USB cable for charging on a laptop/PC/power bank!!!). The charging of the 3 batteries was completed in 2 hours. Once the charging is complete, the device automatically turns off (so you don't have to deal with it). The batteries have been in my possession for a few days, and I don't have an opinion yet. Buy it, it's worth it. The packaging says 4xAA 2600mAh, not 2500mAh. After 3 years of use on a landline phone (to show who's calling), the 3 batteries last for 3 months, and the 4th battery, which is in a wall clock, lasts for 12-13 months. Overall, I am satisfied with their performance and the cost of purchasing the whole package. After 28 months of use, their performance has dropped to 1 month (from being charged for 3 months on my landline phone, all 3 pieces). The 4th one, which is in the clock, works perfectly. I can easily see them lasting for 36 months of use before they need to be replaced.