Can I use the same charger for VRLA batteries and Lithium batteries?

In this blog post, the experts at Valen will take you through the unique charging characteristics for VRLA batteries and Lithium batteries and what can happen if you use the wrong type of charger.

When installing any type of deep cycle battery, it’s important to ensure you use a battery charger suited to the specific battery technology being used.

Lithium Phosphate batteries function very differently from VRLA (Valve Regulated Lead Acid) batteries and therefore have different charging requirements.

First, let’s take a look into deep cycle VRLA battery charger characteristics

In the world of batteries, VRLA batteries are considered to be ‘dumb’ and therefore require a charger that is ‘smart’.

A ‘smart’ battery charger has been pre-programmed with an advanced algorithm dependent on the specific battery technology. This is the same for solar charging with either a PWM or MPPT solar regulator. (See our related blog on the differences between PWM and MPPT solar charger controllers)

A VRLA battery charger or solar controller puts out the required boost voltage into a flat battery. Once the battery hits a predetermined charge level, the charger will automatically switch into float charge mode in order to keep the battery neatly topped up. This float charge mode is essential to ensuring the longevity of VRLA batteries.


So, what about Lithium batteries?

Lithium batteries are a whole different ball game. This is because most Lithium batteries are considered to be ‘smart’ as they have a BMS (Battery Management System) installed inside the battery. The BMS actively regulates the charge coming into the battery from the battery charger or solar controller.

The BMS equalises the charge, keeping all the individual Lithium cells operating together nicely. Because of the function that the BMS performs, most Lithium batteries are charged with a straight 14.4V output. This means that they have a ‘dumb’ charger, or power supply, while the battery itself is ‘smart’. Therefore, Lithium batteries have the total opposite set up to VRLA batteries and chargers.


What happens if I use the wrong battery charger on the wrong battery technology?

As explained above, because of the various battery technologies and charger functionalities, you will most likely incorrectly charge the battery by using the wrong charger type.

If you charge a Lithium battery with a VRLA battery charger, the Lithium battery will never reach full charge, and you will ultimately lose capacity in the battery.

If you charge a VRLA battery with a Lithium battery charger, because the battery charger is not ‘smart’ this means there is no float stage, so the battery is constantly being charged. Ultimately the battery will become hot and will begin to swell or bulge, completely damaging the battery.

Which battery is right for my application?

Need some more information on using the correct type of charger for your battery system?

For further tips, check out our following relevant blog posts:

You can always contact our friendly team for additional support. We’d be happy to answer any questions you have about battery chargers and charging methods. Simply click here to get in touch.

Or you can schedule a no-obligation 15-minute phone chat with one of our experienced battery experts.

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