Question

What is the limit of lead acid discharge?

Answer 1

The limit of lead-acid battery discharge refers to the point at which the battery should not be discharged any further to avoid damaging its lifespan or capacity. Generally, the limit is defined in terms of the depth of discharge (DoD), which is the percentage of the battery's capacity that has been used.

Here are the key points to consider:

1. Recommended Discharge Limit: For most lead-acid batteries, it's recommended to limit the discharge to 50% of the battery's total capacity. This means that if you have a 100Ah (amp-hour) battery, you should ideally not use more than 50Ah before recharging. Discharging beyond 50% can shorten the battery's life and performance.
   

1. Deep Discharge Limit: Lead-acid batteries can tolerate deeper discharges (e.g., 80%) without immediate failure, but repeated deep discharges (using more than 50% of capacity regularly) will significantly reduce the battery’s overall lifespan.
   

1. Voltage Cutoff: Another way to define the discharge limit is by voltage. Typically, the voltage of a fully charged 12V lead-acid battery is around 12.6-12.8V, and it should not be discharged below 10.5V under load. Going below this voltage repeatedly can cause permanent damage to the battery.
   

1. Effect of Over-Discharge: Over-discharging lead-acid batteries can lead to sulfation, where lead sulfate crystals build up on the plates, reducing the battery’s ability to charge and discharge properly. This irreversible process significantly shortens the life of the battery.
   

To sum it up: While you can discharge a lead-acid battery down to about 80% DoD occasionally, for longevity, you should aim for around 50% discharge, and never let the voltage drop too low (below 10.5V) during use.