Well, I'm no expert but my thoughts are that the temperature alone is damaging for the battery (and it will be ~warm since it is basically inside the laptop). U

Well, I'm no expert but my thoughts are that the temperature alone is damaging for the battery (and it will be ~warm since it is basically inside the laptop). Unless you have a way to change it the charge will also be at 100% which is also not ideal. The margins of error are quite small considering that they sometimes explode well within their intended use case (which is not powered on 24/7). The consequences of a fire in a battery is quite severe, and unlike normal laptop usage you probably won't be around it when it starts (or, worse, you might be asleep). So, I'd err on the safe side and buy a UPS that at least covers the intended use case. For something as efficient as a laptop it isn't expensive either.