How Do Lithium and Lead-Acid Battery Chargers Differ?

How Lead-Acid Battery Chargers Work

A lead-acid battery typically consists of six cells, each producing 2 volts, resulting in a total resting voltage of 12 volts. In contrast, a lithium battery is composed of four cells, each with a voltage of 3.2 volts, yielding a resting voltage of 12.8 volts.

This distinction is crucial because lead-acid batteries operate by delivering a low voltage over an extended period. As current flows, it raises the terminal voltage within the battery until it reaches the upper charge voltage. At this point, the battery becomes saturated, and the current begins to decrease.

How Lithium Battery Chargers Work
Lithium battery chargers operate similarly to lead-acid chargers but have a higher voltage per cell and a narrower voltage tolerance. Unlike lead-acid batteries, lithium batteries do not use a trickle charge when fully charged. If a lead-acid battery remains connected after reaching full charge, it can become overcharged. In contrast, lithium chargers are designed to prevent this from happening.

Can You Charge a Lithium Battery with a Lead-Acid Charger?
Using a lead-acid battery charger on a lithium battery can potentially cause damage due to their differing charging requirements. Lead-acid chargers may mimic an exaggerated discharge level that can harm lithium batteries. While some believe you can interchange lead-acid and lithium chargers if you can manually set the maximum charge, experts at BYPOWER advise caution.

They recommend that new lithium battery owners use chargers specifically designed for lithium batteries, such as the ProMariner ProSport HD for LiFePO4 types. Many modern chargers come with lithium charge profiles, as LiFePO4 is the most common lithium chemistry on the market.

Some users may want to continue using their existing lead-acid chargers. While many lead-acid chargers can technically charge lithium batteries, this practice is generally discouraged. Lead-acid chargers may enter a fault code condition, even if the lithium battery appears fully charged. The conditions that trigger these fault codes can cause issues or damage to other electronic systems and even the charger itself. Therefore, it is strongly recommended to use a dedicated lithium battery charger. If you must use a lead-acid charger, opt for those with AGM, Gel, or sealed battery charge profiles to minimize risks.