Here’s the thing – just because a battery can no longer power a high drain device, it doesn’t mean the battery is good for nothing. Car batteries for example have to provide 100s of amps to get that huge engine started. An old/dead car battery might not have the power left to start a high drain engine, but it will likely still be capable of providing a couple of 100 watts of power, which can be used to power things around the home.
Additionally you can use old/dead car batteries with solar panels to provide back-up emergency power on a budget.
As well as reusing car batteries, you can also reuse old sealed lead batteries such as those found in laptops. These might not be able to power the laptop any more, but they can still provide more than enough power to run smaller devices. If you still have the old laptop, you can use it to charge the battery!