The ornamental design for a lead-acid battery, as shown and described.
FIG. 1 shows the front view of the lead-acid battery design, the rear view being a mirror image thereof.
FIG. 2 shows the top view of the lead-acid battery design.
FIG. 3 shows the bottom view of the lead-acid battery design.
FIG. 4 shows the right view of the lead-acid battery design.
FIG. 5 shows the left view of the lead-acid battery design.
FIG. 6 is a perspective view showing the front, top and right of the lead-acid battery design; and,
FIG. 7 is a perspective view showing the front, top and left of the lead-acid battery design.
The broken lines in the drawings are for the purpose of illustrating unclaimed portions of the lead-acid battery and form no part of the claimed design.