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Implement generic battery model

Simscape / Electrical / Specialized Power Systems / Electric Drives / Extra Sources

The Battery block implements a generic dynamic model parameterized to represent most popular types of rechargeable batteries.

This figure shows the battery equivalent circuit that the block models.

For the lead-acid battery type, the model uses these equations:

Discharge Model (i* > 0)

$${f}_{1}\left(it,i*,i,Exp\right)={E}_{0}-K\cdot \frac{Q}{Q-it}\cdot i*-K\cdot \frac{Q}{Q-it}\cdot it+{\text{Laplace}}^{-1}\left(\frac{Exp(s)}{Sel(s)}\cdot 0\right)$$

Charge Model (i* < 0)

$${f}_{2}\left(it,i*,i,Exp\right)={E}_{0}-K\cdot \frac{Q}{it+0.1\cdot Q}\cdot i*-K\cdot \frac{Q}{Q-it}\cdot it+{\text{Laplace}}^{-1}\left(\frac{Exp(s)}{Sel(s)}\cdot \frac{1}{s}\right)$$

For the lithium-ion battery type, the model uses these equations:

Discharge Model (i* > 0)

$${f}_{1}\left(it,i*,i\right)={E}_{0}-K\cdot \frac{Q}{Q-it}\cdot i*-K\cdot \frac{Q}{Q-it}\cdot it+A\cdot \mathrm{exp}\left(-B\cdot it\right)$$

Charge Model (i* < 0)

$${f}_{2}\left(it,i*,i\right)={E}_{0}-K\cdot \frac{Q}{it+0.1\cdot Q}\cdot i*-K\cdot \frac{Q}{Q-it}\cdot it+A\cdot \mathrm{exp}\left(-B\cdot it\right)$$

For the nickel-cadmium and nickel-metal-hydride battery types, the model uses these equations:

Discharge Model (i* > 0)

$${f}_{1}\left(it,i*,i,Exp\right)={E}_{0}-K\cdot \frac{Q}{Q-it}\cdot i*-K\cdot \frac{Q}{Q-it}\cdot it+{\text{Laplace}}^{-1}\left(\frac{Exp(s)}{Sel(s)}\cdot 0\right)$$

Charge Model (i* < 0)

$${f}_{2}\left(it,i*,i,Exp\right)={E}_{0}-K\cdot \frac{Q}{\left|it\right|+0.1\cdot Q}\cdot i*-K\cdot \frac{Q}{Q-it}\cdot it+{\text{Laplace}}^{-1}\left(\frac{Exp(s)}{Sel(s)}\cdot \frac{1}{s}\right).$$

In the equations:

*E*is nonlinear voltage, in V._{Batt}*E*_{0}is constant voltage, in V.*Exp(s)*is exponential zone dynamics, in V.*Sel(s)*represents the battery mode.*Sel(s)*=`0`

during battery discharge,*Sel(s)*=`1`

during battery charging.*K*is polarization constant, in V/Ah, or polarization resistance, in Ohms.*i**is low frequency current dynamics, in A.*i*is battery current, in A.*it*is extracted capacity, in Ah.*Q*is maximum battery capacity, in Ah.*A*is exponential voltage, in V.*B*is exponential capacity, in Ah^{−1}.

The parameters of the equivalent circuit can be modified to represent a particular battery type, based on its discharge characteristics. A typical discharge curve consists of three sections.

The first section represents the exponential voltage drop when the battery is charged. The width of the drop depends on the battery type. The second section represents the charge that can be extracted from the battery until the voltage drops below the battery nominal voltage. Finally, the third section represents the total discharge of the battery, when the voltage drops rapidly.

When the battery current is negative, the battery recharges, following a charge characteristic.

The model parameters are derived from discharge characteristics and assumed to be the same for charging.

The Exp(s) transfer function represents the hysteresis phenomenon for the lead-acid, nickel-cadmium (NiCD), and nickel-metal hydride (NiMH) batteries during charge and discharge cycles. The exponential voltage increases when a battery is charging, regardless of the battery state of charge. When the battery is discharging, the exponential voltage decreases immediately.

For the lithium-ion battery type, the impact of temperature on the model parameters is represented by these equations.

Discharge Model (i* > 0)

${f}_{1}(it,i*,i,T,{T}_{a})={E}_{0}(T)-K(T)\cdot \frac{Q({T}_{a})}{Q({T}_{a})-it}\cdot \left(i*+it\right)+A\cdot \mathrm{exp}\left(-B\cdot it\right)-C\cdot it$

${V}_{batt}(T)={f}_{1}(it,i*,i,T,{T}_{a})-R(T)\cdot i$

Charge Model (i* < 0)

${f}_{1}(it,i*,i,T,{T}_{a})={E}_{0}(T)-K(T)\cdot \frac{Q({T}_{a})}{it+0.1\cdot Q({T}_{a})}\cdot i*-K(T)\cdot \frac{Q({T}_{a})}{Q({T}_{a})-it}\cdot it+A\cdot \mathrm{exp}\left(-B\cdot it\right)-C\cdot it$

${V}_{batt}(T)={f}_{1}(it,i*,i,T,{T}_{a})-R(T)\cdot i,$

with

${E}_{0}(T)={E}_{0}|{}_{{T}_{ref}}+\frac{\partial E}{\partial T}\left(T-{T}_{ref}\right)$

$K(T)=K|{}_{{T}_{ref}}\cdot \mathrm{exp}\left(\alpha \left(\frac{1}{T}-\frac{1}{{T}_{ref}}\right)\right)$

$Q({T}_{a})=Q|{}_{{T}_{a}}+\frac{\Delta Q}{\Delta T}\cdot \left({T}_{a}-{T}_{ref}\right)$

$R(T)=R|{}_{{T}_{ref}}\cdot \mathrm{exp}\left(\beta \left(\frac{1}{T}-\frac{1}{{T}_{ref}}\right)\right),$

where:

*T*is nominal ambient temperature, in K._{ref}*T*is cell or internal temperature, in K.*T*is ambient temperature, in K._{a}*E*/*T*is reversible voltage temperature coefficient, in V/K.α is Arrhenius rate constant for the polarization resistance.

β is Arrhenius rate constant for the internal resistance.

Δ

*Q*/Δ*T*is maximum capacity temperature coefficient, in Ah/K.*C*is nominal discharge curve slope, in V/Ah. For lithium-ion batteries with less pronounced discharge curves (such as lithium iron phosphate batteries), this parameter is set to zero.

The cell or internal temperature,

*T*, at any given time,*t*, is expressed as:$T(t)={L}^{-1}\left(\frac{{P}_{loss}{R}_{th}+{T}_{a}}{1+s\cdot {t}_{c}}\right),$

where:

*R*is thermal resistance, cell to ambient (°C/W)._{th}*t*is thermal time constant, cell to ambient (s)._{c}*P*is the overall heat generated (W) during charge/discharge process and is given by_{loss}${P}_{loss}=\left({E}_{0}(T)-{V}_{batt}(T)\right)\cdot i+\frac{\partial E}{\partial T}\cdot i\cdot T.$

For the lithium-ion battery type, the impact of aging (due to cycling) on the battery capacity and internal resistance is represented by these equations:

$Q(n)=\{\begin{array}{l}{Q}_{BOL}-\epsilon (n)\cdot \left({Q}_{BOL}-{Q}_{EOL}\right)\begin{array}{ccc}& if& k/2\ne 0\end{array}\\ Q(n-1)\begin{array}{ccc}\begin{array}{ccc}\begin{array}{ccc}& & \end{array}& & \end{array}& & otherwise\end{array}\end{array}$

$R(n)=\{\begin{array}{l}{R}_{BOL}+\epsilon (n)\cdot \left({R}_{EOL}-{R}_{BOL}\right)\begin{array}{ccc}& if& k/2\ne 0\end{array}\\ R(n-1)\begin{array}{ccc}\begin{array}{ccc}\begin{array}{ccc}& & \end{array}& & \end{array}& & otherwise\end{array}\end{array},$

with

$n=k{T}_{h}\begin{array}{ccc}& (k=1,2,3,\mathrm{...}\infty )& \end{array}$

where:

*T*is half-cycle duration in s. A complete cycle is obtained when the battery is discharged and charged or conversely._{h}*Q*is battery maximum capacity in Ah, at the beginning of life (BOL), nominal ambient temperature._{BOL}*Q*is battery maximum capacity in Ah at the end of life (EOL), nominal ambient temperature._{EOL}*R*is battery internal resistance in ohms at the BOL, nominal ambient temperature._{BOL}*R*is battery internal resistance in ohms at the EOL, nominal ambient temperature._{EOL}ε is battery aging factor. The aging factor is equal to zero and unity at the BOL and EOL, respectively.

The battery aging factor, ξ, is expressed as

$\epsilon (n)=\{\begin{array}{l}\epsilon (n-1)+\frac{0.5}{N(n-1)}\left(2-\frac{DOD(n-2)+DOD(n)}{DOD(n-1)}\right)\begin{array}{ccc}& if& k/2\ne 0\end{array}\\ \epsilon (n-1)\begin{array}{ccc}\begin{array}{ccc}\begin{array}{ccc}& & \end{array}& & \end{array}& & otherwise\end{array}\end{array},$

where:

*DOD*is battery depth-of-discharge (%) after a half-cycle duration.*N*is maximum number of cycles and is given by$N(n)=H{\left(\frac{DOD(n)}{100}\right)}^{-\xi}\cdot \mathrm{exp}\left(-\psi \left(\frac{1}{{T}_{ref}}-\frac{1}{{T}_{a}(n)}\right)\right)\cdot {\left({I}_{dis\_ave}(n)\right)}^{-{\gamma}_{1}}\cdot {\left({I}_{ch\_ave}(n)\right)}^{-{\gamma}_{2}},$

where:

*H*is cycle number constant (cycles).ξ is exponent factor for the DOD.

ψ is Arrhenius rate constant for the cycle number.

*I*is average discharge current in A during a half cycle duration._{dis_ave}*I*is average charge current in A during a half cycle duration._{ch_ave}*γ*_{1}is exponent factor for the discharge current.*γ*_{2}is exponent factor for the charge current.

**Type**Provides a set of predetermined charge behavior for four types of battery:

`Lead-Acid`

`Lithium-Ion`

(default)`Nickel-Cadmium`

`Nickel-Metal-Hydride`

**Simulate temperature effects**When you select this parameter, the

**Temperature**tab becomes visible and displays the thermal model parameters. The Ta input port becomes visible to supply the ambient temperature. The**Simulate temperature effects**parameter is available only if the**Type**parameter is set to`Lithium-Ion`

. Default is cleared.**Simulate aging effects**Select this parameter to enable the

**Aging**tab becomes visible and display the aging model parameters. To enable the**Simulate aging effects**parameter, set the**Type**parameter to`Lithium-Ion`

. Default is cleared.**Use a preset battery**The parameter contains a list of 10 predetermined temperature parameters of typical lithium-ion batteries. Default is

`no`

. The parameters in the**Temperature**tab are not accessible when a preset is selected. The**Use a preset battery**parameter is available only if the**Type**parameter is set to`Lithium-Ion`

and**Simulate temperature effects**is selected.**Nominal voltage (V)**The nominal voltage,

*Vnom*, of the battery in V. The nominal voltage represents the end of the linear zone of the discharge characteristics. Default is`7.2`

.**Rated capacity (Ah)**The rated capacity,

*Qrated*, of the battery in Ah. The rated capacity is the minimum effective capacity of the battery. Default is`5.4`

.**Initial state-of-charge (%)**The initial state-of-charge (SOC) of the battery. An SOC of 100% indicates a fully charged battery and 0% indicates an empty battery. This parameter is used as an initial condition for the simulation and does not affect the discharge curve (when the option

**Plot Discharge Characteristics**is used). Default is`100`

.**Battery response time (s)**The response time of the battery (at 95% of the final value). Default is

`30`

. This value represents the voltage dynamics and can be observed when a current step is applied.This example uses the battery response time of 30 s.

**Determined from the nominal parameters of the battery**Load the corresponding parameters in the entries of the dialog box, depending on the selected

**Type**, the**Nominal voltage**, and the**Rated capacity**.When a preset model is used, the detailed parameters cannot be modified. If you want to modify the discharge curve, select the desired battery type to load the default parameters, and then clear the

**Determined from the nominal parameters of the battery**check box to access the detailed parameters. Default is cleared.**Maximum capacity (Ah)**The maximum theoretical capacity,

*Q*, when a discontinuity occurs in the battery voltage in Ah. This value is generally equal to 105% of the rated capacity. Default is`5.4`

.**Cut-off voltage (V)**The minimum allowable battery voltage in V. This voltage represents the end of the discharge characteristics. At the cut-off voltage, the battery is fully discharged. Default is

`5.4`

.**Fully charged voltage (V)**The fully charged voltage,

*Vfull*, for a given discharge current. The fully charged voltage is not the no-load voltage. Default is`8.3807`

.**Nominal discharge current (A)**The nominal discharge current, for which the discharge curve has been measured, in A. For example, a typical discharge current for a 1.5-Ah NiMH battery is 20% of the rated capacity: (0.2 * 1.5 Ah / 1 h = 0.3 A). Default is

`2.3478`

.**Internal resistance (Ohms)**The internal resistance of the battery in ohms. When a preset model is used, a generic value is loaded, corresponding to 1% of the nominal power (nominal voltage multiplied by the battery rated capacity). The resistance is supposed to be constant during the charge and the discharge cycles and does not vary with the amplitude of the current. Default is

`0.013333`

.**Capacity (Ah) at nominal voltage**The capacity,

*Qnom*, extracted from the battery until the voltage drops under the nominal voltage. This value should be between*Qexp*and*Qmax*. Default is`4.8835`

.**Exponential zone [Voltage (V), Capacity (Ah)]**The voltage,

*Vexp*, and the capacity,*Qexp*, corresponding to the end of the exponential zone. The voltage should be between*Vnom*and*Vfull*. The capacity should be between 0 and*Qnom*. Default is`[7.7788 0.2653]`

.**Discharge current [i1, i2, i3,...] (A)**Allows specifying different values of discharge current. The discharge characteristics for these currents are presented in the second part of the graph. Default is

`[6.5 13 32.5]`

.**Units**Choose either

`Time`

(default) or`Ampere-hour`

as the*x*-axis for the plot.**Plot**Plots a figure containing two graphs. The first graph represents the nominal discharge curve (at the

**Nominal Discharge Current**) and the second graph represents the discharge curves at the specified discharge currents.

To enable this tab, set the **Type** parameter
to `Lithium-Ion`

and select **Simulate
temperature effect**.

**Initial cell temperature (deg. C)**The initial cell or internal temperature of the battery, in °C. Default is

`20`

.**Nominal ambient temperature T1 (deg. C)**The ambient temperature, in °C, at nominal condition of operation. It is assumed that all parameters provided in the

**Parameters**tab are obtained at this ambient temperature. Default is`20`

.**Second ambient temperature T2 (deg. C)**The ambient temperature, in °C, at the second operating condition, preferably below the nominal ambient temperature. Default is

`-30`

.**Maximum capacity (Ah)**The maximum battery capacity, in Ah, at the second ambient temperature. Default is

`4.8`

.**Initial discharge voltage (V)**The initial discharge voltage at the second ambient temperature, in V, when the discharge current is applied. Default is

`7.1`

.**Voltage at 90% maximum capacity (V)**The discharge voltage, in V, when 90% of the maximum capacity is used, at the second ambient temperature. Default is

`5.655`

.**Exponential zone [Voltage (V), Capacity (Ah)]**The discharge voltage, in volts, and the capacity, in Ah, corresponding to the end of the exponential zone, at the second ambient temperature. Default is

`[6.58 1]`

.**Thermal resistance, cell-to-ambient (deg. C/W)**The total thermal resistance, in °C/W, between the cell and ambient points of measurement. It is assumed the cell temperature is equivalent to the average internal temperature of the battery. Default is

`0.6`

.**Thermal time constant, cell-to-ambient (s)**The temperature response time constant, in seconds, between the cell and ambient points of measurement. You can obtain this value from the ambient temperature step response while the battery is in idle mode. Default is

`2000`

.**Heat loss difference [charge vs. discharge] (W)**The power loss difference between charge and discharge in W, when the battery is charged and discharged at the same C-rate and ambient temperature. Default is

`0`

.Determine the power loss difference (Δ

*P*) using the following expression:$$\Delta P=\frac{{t}_{c}({\theta}_{2}-{\theta}_{1})}{{R}_{th}}$$

where

*θ*and_{1}*θ*are the rates of change of the battery internal temperature (°C/s) during discharge and charge, respectively._{2}

To enable this tab, set the **Type** parameter
to `Lithium-Ion`

and select **Simulate aging
effect**.

**Initial battery age (Equivalent full cycles)**Battery age or equivalent full cycles at the beginning of the simulation. A full cycle is defined as a complete discharge and charge to 100% DOD and 100% SOC, respectively, at a nominal ambient temperature and nominal discharge and charge current. Default is

`0`

.**Aging model sampling time (s)**Simulation time step of the aging model, in s. Default is

`1e6`

.**Ambient temperature Ta1 (deg. C)**First ambient temperature during the aging performance test, in °C. Default is

`25`

.**Capacity at EOL (End of Life) (Ah)**Maximum capacity at EOL at ambient temperature Ta1, in Ah. Default is

`5.4*0.9`

.**Internal resistance at EOL (Ohms)**Internal resistance at EOL at ambient temperature Ta1, in ohms. Default is

`0.013333*1.2`

.**Charge current (nominal, maximum) [Ic (A), Icmax (A)]**Nominal and maximum charge current in A. Default is

`[2.3478, 3]`

.**Discharge current (nominal, maximum) [Id (A), Idmax (A)]**Nominal and maximum discharge current in A. Default is

`[2.3478, 10]`

.**Cycle life at 100 % DOD, Ic and Id (Cycles)**Number of cycles at 100% DOD, nominal charge and discharge current, first ambient temperature. Default is

`1500`

.**Cycle life at 25 % DOD, Ic and Id (Cycles)**Number of cycles at 25% DOD, nominal charge and discharge current, first ambient temperature. Default is

`10500`

.**Cycle life at 100 % DOD, Ic and Idmax (Cycles)**Number of cycles at 100% DOD, nominal charge current, maximum discharge current, first ambient temperature. Default is

`1000`

.**Cycle life at 100 % DOD, Icmax and Id (Cycles)**Number of cycles at 100 % DOD, maximum charge current, nominal discharge current, first ambient temperature. Default is

`1400`

.**Ambient temperature Ta2 (deg. C)**Second ambient temperature, in °C, during the aging performance test. Default is

`45`

.**Cycle life at 100 % DOD, Ic and Id (Cycles)**Number of cycles at 100% DOD, nominal charge and discharge current, second ambient temperature. Default is

`950`

.

This figure shows detailed parameters extracted from the Panasonic NiMH-HHR650D battery data sheet.

From the specification tables, obtain the rated capacity and the internal resistance. The other detailed parameters are derived from the Typical Discharge Characteristics plot.

Parameter | Value |
---|---|

Rated Capacity | 6.5 Ah |

Internal Resistance | 2 mΩ |

Nominal Voltage | 1.18 V |

Rated Capacity | 6.5 Ah |

Maximum Capacity | 7 Ah (5.38 h * 1.3A) |

Fully Charged Voltage | 1.39 V |

Nominal Discharge Current | 1.3 A |

Capacity @ Nominal Voltage | 6.25 Ah |

Exponential Voltage | 1.28 V |

Exponential Capacity | 1.3 Ah |

These parameters are approximate and depend on the precision of the points obtained from the discharge curve. You can use a tool called ScanIt (provided by amsterCHEM, https://www.amsterchem.com) to extract values from data sheet curves.

The discharge curves you obtain with these parameters, marked by dotted lines in next plots, are similar to the data sheet curves.

To represent temperature effects of the lithium-ion (Li-ion) battery type, an additional discharge curve at ambient temperature different from the nominal temperature is required along with the thermal response parameters. Additional discharge curves are not usually provided on the data sheet and may require simple experiments to be obtained. The following examples show parameters extracted from the A123 Li-iron-phosphate ANR26650M1 and the Panasonic Li-cobalt-oxide CGR 18,650 AF battery data sheets.

The A123 ANR26650M1 data sheet specifications include the required discharge curve points, along with other required parameters.

From the data sheet, these parameters are derived for the A123 Li-ion temperature-dependent battery model.

Parameter | Value |
---|---|

Nominal voltage (c) | 3.22 V |

Rated capacity | 2.3 Ah |

Maximum capacity (d) | 2.3 Ah |

Fully charged voltage (a) | 3.7 V |

Nominal discharge current | 2.3 A |

Internal resistance | 10 mΩ |

Capacity at nominal voltage (c) | 2.07 Ah |

Exponential zone (b) | [3.4 V, 0.23 Ah] |

Nominal ambient temperature | 25 °C |

Second ambient temperature | 0 °C |

Maximum capacity at 0 °C (h) | 2.208 Ah |

Initial discharge voltage at 0 °C (e) | 3.45 V |

Voltage at 90% maximum capacity at 0 °C (g) | 2.8 V |

Exponential zone at 0 °C (f) | [3.22 V, 0.23 Ah] |

Thermal resistance, cell-to-ambient (estimated) | 0.6 |

Thermal time constant, cell-to-ambient (estimated) | 1000 |

In the figure, the dashed lines show the discharges curves obtained from the simulation at different ambient temperatures. The model performance is very close to the data sheet results.

The same approach for parameter extraction is applied to the Panasonic Lithium-Ion CGR18650AF with these specifications.

These parameters are extracted for the battery model.

Parameter | Value |
---|---|

Nominal voltage (c) | 3.3 V |

Rated capacity | 2.05 Ah |

Maximum capacity (d) | 2 Ah |

Fully charged voltage (a) | 4.2 V |

Nominal discharge current | 1.95 A |

Internal resistance (estimated) | 16.5 mΩ |

Capacity at nominal voltage (c) | 1.81 Ah |

Exponential zone (b) | 3.71 V, 0.6 Ah |

Nominal ambient temperature | 25 °C |

Second ambient temperature | 0 °C |

Maximum capacity at 0 °C (h) | 1.78 Ah |

Initial discharge voltage at 0 °C (e) | 4 V |

Voltage at 90 % maximum capacity at 0 °C (g) | 3.11 V |

Exponential zone at 0 °C (f) | 3.8 V, 0.2 Ah |

Thermal resistance, cell-to-ambient (estimated) | 0.06 |

Thermal time constant, cell-to-ambient (estimated) | 1000 |

The figure shows a good match between the simulated discharge curves (dashed line) and the data sheet curves. The accuracy of the model depends on how precise the selected points from the data sheet discharge curves are.

To model a series and/or parallel combination of cells based on the parameters of a single
cell, the parameter transformation shown in the next table can be used. The
`Nb_ser`

variable corresponds to the number of cells in series, and
`Nb_par`

corresponds to the number of cells in parallel.

Parameter | Value |
---|---|

Nominal voltage | 1.18 * Nb_ser |

Rated capacity | 6.5 * Nb_par |

Maximum capacity | 7 * Nb_par |

Fully charged voltage | 1.39 * Nb_ser |

Nominal discharge current | 1.3 * Nb_par |

Internal resistance | 0.002 * Nb_ser/Nb_par |

Capacity at nominal voltage | 6.25 * Nb_par |

Exponential zone | 1.28 * Nb_ser, 1.3 * Nb_par |

`m`

The Simulink

^{®}output of the block is a vector containing seven signals. You can demultiplex these signals by using the Bus Selector block provided in the Simulink library.Signal

Definition

Units

Ambient Temperature

The Ambient temperature (available only when temperature effects is enabled)

°C

Cell Temperature

The cell or internal temperature (available only when temperature effects is enabled)

°C

SOC

The battery state-of-charge (between 0 and 100%). The SOC for a fully charged battery is 100% and for an empty battery is 0%. The SOC is calculated as:

$$SOC=100\left(1-\frac{1}{Q}{\displaystyle {\int}_{0}^{t}i(t)\text{\hspace{0.17em}}dt}\right).$$

%

Current

The battery current

A

Voltage

The battery voltage

V

Age

The battery age (available only when aging effects are enabled)

Equivalent full cycles

Maximum Capacity

The battery maximum capacity (available only when aging effects are enabled)

Ah

`Ta`

The input port to supply the ambient temperature to the model. To enable this port, set the

**Type**parameter to`Lithium-Ion`

and select**Simulate temperature effects**.

Experimental validation of the model shown a maximum error of 5% (when SOC is between 10% and 100%) for charge (current from 0 through 2 C) and discharge (current from 0 through 5 C) dynamics.

The internal resistance is assumed constant during the charge and discharge cycles and does not vary with the amplitude of the current.

The parameters of the model are derived from discharge characteristics and assumed to be the same for charging.

The capacity of the battery does not change with the amplitude of current (No Peukert effect).

The self-discharge of the battery is not represented. It can be represented by adding a large resistance in parallel with the battery terminals.

The battery has no memory effect.

The minimum no-load battery voltage is 0 V and the maximum battery voltage is equal to 2 ×

*E*._{0}The minimum capacity of the battery is 0 Ah and the maximum capacity is Qmax.

The `power_battery`

example
illustrates a 200 V, 6.5-Ah NiMH battery connected to a constant load of 50 A.

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