NO!!! to used battery lead
DO NOT UNDER ANY CIRCUMSTANCES USE A CAR BATTERY FOR LEAD!!!
1. Sulfuric acid will burn your skin
2. Sulfuric acid vapor will burn your nose, throat & sinus cavities.
3. Sulfuric acid is volatile and can/will explode when exposed to sparks. Check out the warning tags on your battery. Could you imagine that stuff EXPLODING on your face, arms and hands?
4. You can not just "wash" the acid off of the lead to clean it up to use.
5. Besides, whatcha gonna do with a quart of nasty acid? Can't pour it out...don't want to save it...
I'm not much of a recycler, but in this instance ALWAYS take any auto/truck/deep cycle battery to a battery recycling place. Most places charge you a "core charge" - if you don't bring a dead battery in, they add $5 - $10 to your ticket. Some places will take old dead batts off your hands for nothing; others charge a few bucks.
Get that old battery out of your yard. It's not doing you any good.
Take it from an old car garage guy - if you've ever seen what battery acid can do (or had just a slight whiff of the stuff "sting" the nose and eyes), you will understand why I am saying what I am saying.
Preacher Man