Why is my RV battery not fully charging?

Understanding the Converter Dial

On RecPro converters, there’s a small adjustable dial called a potentiometer. It controls both the charging mode and the voltage level.

The sticker beside it can be confusing, but here’s how to read it:

• The left side of the dial controls four-stage smart charging, designed for lead-acid batteries.

• The right side of the dial is intended for lithium-ion batteries or for powering appliances directly in your RV.

Once you’ve chosen the correct side for your setup, you can fine-tune the voltage:

• Lower voltage: turn the dial toward the top.

• Higher voltage: turn the dial toward the side you’re using.

Factory Default Settings

Converters are typically shipped in four-stage smart charging mode (the left side of the dial).

If you’re not sure which mode yours is in, you can tell by watching the LED light indicator while turning the dial with a screwdriver.

When the LED flickers, that means you’ve crossed over to the other side of the dial, switching between smart charging and lithium/direct power modes.

Fine-Tuning and Voltage Adjustment

For a more precise setup, you can use a multimeter to check the output voltage while adjusting the potentiometer. This helps confirm you’re within the proper range for your specific battery.

Keep in mind that different battery types require different voltage targets for optimal charging. You should always check the manual or specifications for your battery brand to confirm the best settings, especially for lithium batteries, which can vary in chemistry and built-in protection systems.

If you’re just trying to get oriented with the dial and make sure your converter is working correctly, these general guidelines will help you get in the right direction.

Why It Stops Around 80%

If your converter seems to charge your lead-acid battery only up to about 80%, that’s usually by design. In four-stage smart charging mode, the converter is programmed to stop before hitting full voltage to prolong the battery’s lifespan.

Fully charging a lead-acid battery every time can cause unnecessary stress and shorten its life.Lithium batteries may charge differently and reach higher levels depending on how the converter and BMS are configured.

In Short

• Left side of the dial: smart charging (lead-acid)

• Right side: lithium or direct power mode

• LED flicker: indicates switching between modes

• Multimeter: use to fine-tune voltage

• 80% charge: normal for smart charging mode

• Always check your battery manual: ideal voltages vary by type

If your converter is working correctly but your battery isn’t quite reaching 100% it doesn’t mean something’s broken, it’s probably doing exactly what it should.