A tiny battery generates a very tiny amount of heat. Batteries have internal resistance, so charging and discharging is not perfectly efficient. Larger batterie

A tiny battery generates a very tiny amount of heat. Batteries have internal resistance, so charging and discharging is not perfectly efficient. Larger batteries generate much more heat by moving larger amounts of energy. Secondly, consider the relationship between volume and surface area. Volume grows to the power of 3, and area grows to the power of 2. A small battery naturally has a much lower ratio of volume to surface area than a big battery. With a higher ratio, it takes a lot longer for the heat to be lost to the cold because of how heat transfer works, and that's in addition to the larger batteries generating much more total heat energy. Thirdly, consider that the goal of an iPhone is to use as little power as possible so that your battery lasts as long as possible, which also means generating as little heat as possible. A grid battery does not have that same goal. It is not a "hilarious oversight". Heat pumps are incredibly efficient these days even in very cold weather and there are ways to mitigate the heat loss, such as insulation. Grid scale battery deployments up to this point are typically already done in small structures, so the batteries aren't just sitting out directly in the elements. Obviously it's better if you don't have to do anything at all, but it is a very legitimate option. Every system will have some losses, no matter what. A very efficient heat pump could result in less losses than relying on the batteries to resistively heat themselves in extreme cold. Just because it wouldn't work for a phone has nothing to do with how it would work for a grid battery, since scaling things up has a dramatic impact on efficiency for what we're discussing. For how condescending your comment seemed to be, you seem to be missing a lot of basic points. Please give people the benefit of the doubt. I didn't come here to be a jerk to anyone, I was trying to help people understand things they seemed to be missing, but HN got super toxic over this topic. Some of this stuff is very nuanced and difficult to explain, which means that some people have no patience for it. If I'm wrong about things, or make a mistake in my explanation, I'm always happy to learn, but your comment was not attempting to teach anything.