I bought a nice cordless Makita drill with a pair of 18V Lithium batteries almost 6 years ago. Since then, I've added a cordless saw, sander, and planer to the system. I have been very happy with all of my tools. They're clearly well made, and I've had full use out of them every summer.
I had a bit of a disappointment on my last visit, however. Both of my batteries would no longer charge. I was not happy, seeing how expensive they are! But after talking to Olle and Janne, it seems that I was perhaps uncharitable. They've lasted over 5 years, and my pattern of using them a lot for short times and then setting for a long time in cold weather is hard on a rechargeable battery.
Substitutes for the original Makita batteries are available from many different suppliers at a much lower cost. On the other hand, if my battery fails, I'm totally without a power tool. So I compromised and bought one official battery and one aftermarket model.
I'll do my best to take better care of them in the future. I will also report how well the aftermarket battery holds up. I could save a lot of money over the years!