What do I do with a dead UPS?

Question: My UPS is dead and I need to dispose of it. Is there any kind of special consideration here (is it dangerous?), or can I just dump it into the trash?
 
The answers to those three questions are yes, it can be, and no. Most of the batteries used in UPS systems are lead-acid, the same technology used in a car battery, so most of the things you've heard about those apply here. The batteries are sealed, and as long as that seal remains intact, the biggest danger—exposure to the sulfuric acid within—is minimal. Hit it with the compaction used by most garbage trucks, however, and you run the risk of giving someone an acid bath.

Even if the acid weren't an issue, however, you wouldn't want to just dump the battery into the local municipal waste stream. Lead is a potent toxin, with both immediate and chronic effects, so it needs to be disposed of properly. That's also true of cadmium, an ingredient of the primary alternative to lead-acid batteries, the Ni-Cd. So, no matter which type of UPS you've got, the contents of its battery are toxic. Try to avoid eating it, and don't just dump it in the trash.

Because they have toxic ingredients, disposal of batteries is regulated by the Environmental Protection Agency. The rules there are rich in bureaucratese (an example: "Batteries, as described in Sec. 273.9, that are not yet wastes under part 261 of this chapter, including those that do not meet the criteria for waste generation in paragraph (c) of this section."), but the EPA has also provided some human-readable advice. The feds are not the only ones with regulations; most states and a number of municipalities have their own rules governing how spent batteries are handled. The end result of this regulation is that the manufacturers of batteries that contain toxic waste are responsible for recycling them once they're no longer in use.

Notice that's "recycled," and not "disposed of." The rules require that the batteries get recycled, and many major manufacturers have banded together to form a non-profit company that collects the batteries and sends them into a single recycling stream; the vast majority of the lead and cadmium reclaimed from batteries ends up right back in other batteries. Many companies have their own programs in place for returning the spent batteries to them (APC's program, for example, lets you download a prepaid shipping label online).
If your manufacturer is not so generous, you may still be in luck, as the non-profit mentioned above also helps collect the batteries from consumers. A trip to its homepage lets you enter a zip code and find a battery drop-off location.

The EPA also recommends a similar resource.

If that's too much work, your state may make life even easier. In New York, for example, any place that sells batteries is required by law to accept them. As a result, the battery can be taken to any office supply, home improvement store, or drugstore.

So, in summary: your UPS's battery contains toxic ingredients; although these don't present a danger as long as the battery is intact, it's illegal to to dispose of it in the trash. Fortunately, you have plenty of options for getting rid of it safely, and with the knowledge that the toxic chemicals will be recycled.

 http://arstechnica.com/gadgets/2011/02/ask-ars-what-do-i-do-with-a-dead-ups/