# Custom battery
This guide applies to the [easy-pv.co.uk](https://easy-pv.co.uk/) and [easy-pv.ie](https://easy-pv.ie) versions of Easy PV. The information provided here may not be accurate for easy-pv.com.
To add a custom battery in Easy PV navigate to **My Components** > **Batteries** on the left-side menu or **Components** > **Edit Batteries** from the top drop down menu. You will need the datasheet from the manufacturer, below you will find guidance on how the information in the datasheet corresponds to the values Easy PV asks for.If your custom battery is not showing up in the inverter task, see the 'Additional details' section and check the compatibility is correct.
#### **Inputting information from datasheet** Below is a list of definitions and potential variations for each value on different manufacturer data sheets:**Technical info** | **Variations** |
---|---|
**Battery Capacity:** total battery capacity. Usable capacity may be less if there is a max permitted discharge depth. | - Battery module energy - Battery system capacity |
**Max Discharge:** maximum depth to which the manufacturer recommends that this battery is discharged. Typically 80 or 90%. | - Depth of discharge |
**Round Trip Efficiency:** percentage of electricity recovered from the battery in a charge-discharge cycle. Around 95% is typical for lithium ion batteries. | - Peak round-trip efficiency |