I have three UPSes running in the house, two of them have been up for the past 9-10 years now. Needless to say that through the years, I've collected several depleted sealed lead-acid (VRLA) batteries. Now, I know that I can't just throw these away in the trash and hope for the best... no. They've been in storage until now along with a few old motorcycle & car batteries, plus a number of NiCd & NiMH cells. Because of this, a part of my workshop quite literally became a toxic waste dump.

Frankly, I want to get rid of them, but in a correct and environmentally-friendly way. Any ideas?