Question

At what voltage is a lead acid battery dead?

Answer 1

A lead-acid battery is considered "dead" or fully discharged when its voltage drops to about 10.5 volts or lower.

Here’s a breakdown of the typical voltage levels:

1. 12.6-12.8 volts: Fully charged (after charging).
   

1. 12.0-12.4 volts: A partially charged battery, still functional.
   

1. 11.8 volts: About 50% charge.
   

1. 10.5 volts or lower: The battery is considered dead or discharged, and if left in this state for too long, it can be damaged.
   

It’s important to note that lead-acid batteries should ideally not be discharged below 10.5 volts because this can lead to sulfation (a process where lead sulfate crystals form on the battery plates), which can permanently damage the battery. Regularly discharging them too deeply will shorten their lifespan.