# Battery (System-Level)

**Libraries:**

Simscape /
Driveline /
Sources

## Description

The Battery (System-Level) block represents a generic self-discharging battery. You can use the block to model hybrid and battery electric drives at a medium-level fidelity for drive cycle analysis. The block is a simplified version of the Battery (Simscape Electrical) block and uses the same parameters, where applicable. This will aid your transition to a higher fidelity model, if necessary. The Battery (System-Level) does not support battery fade, aging, dynamics, or temperature dependent properties. You can access these features using the Battery (Simscape Electrical) block.

You can choose to simulate a battery with finite or infinite charge. The block can also help you to determine how decreased voltage affects performance and control requirements. To learn more about observing battery performance, see Plot Basic Characteristics for Battery Blocks (Simscape Electrical).

### Battery Model

When you set **Battery charge capacity** to
`Infinite`

, the block treats the battery like a
resistor and a constant voltage source in series. When you set **Battery
charge capacity** to `Finite`

, the block
treats the battery like a resistor and a charge-dependent voltage source in series.
In this case, the voltage is a function of charge and has the following
relationship:

$$V={V}_{0}\left(\frac{\text{SOC}}{1-\beta (1-\text{SOC})}\right)$$

where:

`SOC`

(state-of-charge) is the ratio of current charge to rated battery capacity.*V*_{0}is the voltage when the battery is fully charged at no load, as defined by the**Nominal voltage, Vnom**parameter.*β*is a constant that is calculated so that the battery voltage is*V1*when the charge is*AH1*. Specify the voltage*V1*and ampere-hour rating*AH1*using block parameters.*AH1*is the charge when the no-load (open-circuit) voltage is*V1*, and*V1*is less than the nominal voltage.

The equation defines an approximate relationship between voltage and remaining charge. This approximation replicates the increasing rate of voltage drop at low charge values and ensures that the battery voltage becomes zero when the charge level is zero. The advantage of this model is that it requires few parameters, which are typically available on manufacturer datasheets.

### Variables

To set the priority and initial target values for the block variables prior to simulation,
use the **Initial Targets** section in the block dialog box or Property
Inspector. For more information, see Set Priority and Initial Target for Block Variables.

Nominal values provide a way to specify the expected magnitude of a variable in a model.
Using system scaling based on nominal values increases the simulation robustness. Nominal
values can come from different sources, one of which is the **Nominal
Values** section in the block dialog box or Property Inspector. For more
information, see Modify Nominal Values for a Block Variable.

### Assumptions and Limitations

The block assumes that self-discharge resistance does not depend on the number of discharge cycles.

## Ports

### Conserving

## Parameters

## Extended Capabilities

## Version History

**Introduced in R2022a**

## See Also

Battery (Simscape Electrical)