A few months ago I bought an Anker A1336 72 Wh power bank with a nice display, supporting 3 USB ports, 100W charge and discharge power and simultaneous loading and discharge. All in all, a great power bank, and I reviewed it here and here. However. there are a number of limitations mostly related to prevent overheating, of which I only became aware while using the power bank extensively. So let’s have a look:
When charging or discharging the power bank, its temperature rises, and while you don’t go to the specified charge/discharge power limits you probably won’t notice. But try to recharge the power bank with a 65W power supply while at the same time connecting a notebook and mobile phones, all with low batteries and high power draw, and you will notice a quick rise in the power bank’s temperature, which in turn quickly leads to counter measures.
The main limitation: When the temperature of the power bank reaches 42 degrees as seen on its display, supplying power to other devices stops. In addition, the power bank will only charge itself with 22W once temperature has risen beyond 42 degrees. In such a setup and normal outside temperatures, it takes about half an hour to get to this state when discharging the power bank at a rate of 70W + 20W. Note that it doesn’t feel hot on the outside, it just feels warm to the touch. Perhaps the cells inside are much warmer because 42 degrees doesn’t strike me as very hot.
Once the power bank has cooled down a bit, normal operation resumes automatically. So how did I discover the limitation?: After a long day on battery, it sometimes happens to me that the power bank and my other devices are all empty at the same time. As the power bank can charge and discharge simultaneously, I thought I could just use one power supply to recharge the power bank and from there forward a part of the power to my notebook and two phones simultaneously. All devices will charge slower but that would have been acceptable. But slowing down recharging to 22W instead of the maximum 100W and shedding the connected devices makes the process take a lot longer than I would have anticipated.
Still, I like the power bank a lot, and I’m glad it doesn’t have a fan, as I prefer silence to a running fan.