Are Lead-Acid and Lithium Battery Chargers Interchangeable?

Posted May 18, 2023

If you use lithium batteries, you may wonder if you can charge your lithium battery with your lead-acid battery charger. This may not be a good idea because, despite lead-acid battery chargers technically being able to charge a lithium battery, there are vital voltage and energy differences to keep in mind so as to prevent you from potentially damaging your lithium battery. For example, lead-acid battery chargers usually deliver a constant voltage, whereas lithium battery chargers deliver both voltage and current that are constant. Below we cover the main distinctions between lithium and lead-acid battery chargers and how to determine which one is right for you.

ProMariner ProSport HD6 LiFePO4 Battery Charger

What Are the Differences Between Lead-Acid and Lithium Battery Chargers?

Both types of chargers can charge your battery to 14.6 volts, but they have unique ways in which they get your battery there. From charge speeds to higher voltage requirements, we have summarized the most important factors to consider when comparing these two types of battery chargers:

Lead Acid Battery Chargers

A lead-acid battery is generally made up of 6 cells that each have 2 volts. This results in a resting voltage that is 12 volts. On the other hand, a lithium battery has 4 cells that each have 3.2 volts, which results in a resting voltage of 12.8 volts. This is important to keep in mind because lead-acid batteries function by providing a battery with low voltage over a long period of time. This works due to the current raising the terminal voltage inside the battery until the upper charge voltage is achieved, at which point the battery becomes saturated, and the current drops.

Lithium Battery Chargers

A lithium battery charger works similarly, except that it has a higher voltage per cell and a more narrow voltage tolerance. Additionally, a lithium battery does not have a trickle charge when it is at full charge. When a lead acid battery remains connected for too long, it can become overcharged once it receives a full charge. A charger meant for a lithium battery will be built to ensure this does not happen when it is at full charge.

ProMariner ProTournament 240 LiFePO4 Battery Charger

Can You Use a Lead-Acid Battery Charger To Charge a Lithium Battery?

Sometimes using a lead-acid battery charger for a lithium battery can result in damage due to the differences in how the two observe the battery’s charging stage. When a lithium battery has a different ideal discharge level, a lead-acid battery will mimic an exaggerated amount of discharge that can damage the lithium battery. Some believe that you should be able to use lead-acid and lithium chargers interchangeably as long as you can set the maximum charge of the battery yourself.

However, after nearly a decade of experience in the field, the experts at RELiON agree that you should be wary of any advice that attempts to conflate the charging needs of these two batteries. We encourage new Lithium battery owners to use a charger that has a Lithium specific charge profile, like the ProMariner ProSport HD, for LiFePO4 batteries. These are easy to find since most chargers on the market today have a lithium charge profile, and LiFePO4 is the predominant Lithium battery chemistry in the marketplace. However, some customers would like to continue using their existing Lead-Acid charger if possible. Although many existing lead-acid chargers will still charge our Lithium battery, it is generally discouraged to do this. The risk is the lead-acid chargers may wind up in fault code condition at some point, despite the Lithium battery probably having received a full recharge. The problem is that the conditions incurred during the fault codes can also cause issues and/or damage to other system electronics, and even the charger itself. Therefore, we strongly recommend you use a Lithium battery charger. If this recommendation is neglected then it is best to choose AGM, Gel, sealed battery charge profiles to charge a Lithium battery.

How Do I Know Which Charger Is Right For My Battery?

If you are not sure what your best charging options are for your lithium battery, you can reach out to a RELiON specialist to receive help on your available choices and whether or not you are making the right choice.