# What is the capacitive load?

#### AIBang

Joined Feb 3, 2024
26
What is the capacitive load and how can capacitive load be simulated? I want to monitor the current and voltages in the simulation by powering a capacitive load from the battery, but I am not sure whether I am doing this correctly.

#### Dodgydave

Joined Jun 22, 2012
11,318
A capacitor will just charge up then very little current will flow, you're better using AC .

#### AIBang

Joined Feb 3, 2024
26
A capacitor will just charge up then very little current will flow, you're better using AC .
So how should I add resistors?

#### Dodgydave

Joined Jun 22, 2012
11,318
You can use any value of resistors and any value of capacitors, the time constant for DC is T = RC, where T is in seconds .
On AC the current will depend on the capacitance and Frequency of the voltage.

#### LowQCab

Joined Nov 6, 2012
4,186
What is the capacitive load and how can capacitive load be simulated? I want to monitor the current and voltages in the simulation by powering a capacitive load from the battery, but I am not sure whether I am doing this correctly.
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The term "Capacitive-Load" usually refers to directly driving a Capacitor,
which is connected to Ground,
with an Amplifier.

Most Amplifiers tend to behave badly when driving a directly connected Capacitive-Load.

You need to provide much more information as to what You are attempting to accomplish overall,
and what type of Circuit You are attempting to use to achieve those goals.

Generally, a Capacitive-Load can be considered to be a Short-Circuit to Ground for AC-Amplifiers.
Therefore, a Resistor is needed to limit the maximum Current demanded from the Amplifier by the Capacitor.
And, of course, this would mean that there is now zero Capacitive-Load on the Amplifier, only a Resistive-Load.

Please provide a Schematic or, at least a Block-Diagram of your Circuit.
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#### BobTPH

Joined Jun 5, 2013
9,109
Two examples of real life capacitive loads are piezo transducers and electroluminescent (EL) wire or panels.

To model one in LTSPICE you use, ready? A capacitor.

#### AIBang

Joined Feb 3, 2024
26
.
The term "Capacitive-Load" usually refers to directly
which is connected to Ground,
with an Amplifier.

Most Amplifiers tend to behave badly when driving a directly connected Capacitive-Load.

You need to provide much more information as to what You are attempting to accomplish overall,
and what type of Circuit You are attempting to use to achieve those goals.

Generally, a Capacitive-Load can be considered to be a Short-Circuit to Ground for AC-Amplifiers.
Therefore, a Resistor is needed to limit the maximum Current demanded from the Amplifier by the Capacitor.
And, of course, this would mean that there is now zero

Please provide a Schematic or, at least a Block-Diagram of your Circuit.
.
.
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Two examples of real life capacitive loads are piezo transducers and electroluminescent (EL) wire or panels.

To model one in LTSPICE you use, ready? A capacitor.
The purpose of the ltspice simulation is connect a load between the PACK+ and PACK- legs of the BMS and monitoring the current and voltages of the capacity in the load while charging. But my simulation results are not what they should be. I couldn't find the problem. When you run the simulation, the current passing through the load capacitance starts to decrease after a meaningless peak. At the same time, the load capacitor should not be fully charged when the FETs are off, but it is. I couldn't find a solution to these errors, so I'm doing research. I would be happy if you help. If the load capacitor can charge while the FETs are off, there is no point in pre-discharging anyway. The purpose of pre-discharge is to prepare the capacitor for discharge current by charging it to a certain level when the load is connected.

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#### BobTPH

Joined Jun 5, 2013
9,109
A battery is not a capacitive load. If you are using a capacitor to model a battery, it is not going to be accurate.

#### AIBang

Joined Feb 3, 2024
26
A battery is not a capacitive load. If you are using a capacitor to model a battery, it is not going to be accurate.
I am not modeling the battery. I am providing power to a load from the battery. I'm actually trying to model the load.

#### LowQCab

Joined Nov 6, 2012
4,186
I don't know anything about LTSpice,
but the Simulation-Program that I use will let You simply insert an Ammeter into the Supply-Line,
giving an additional graphic-display of the Current within any time-frame that is selected.

I've always found it to be brutally accurate when all parasitic qualities of
the various Components are properly entered.

Why do You need to know the Inrush-Current ?,
wasn't Inrush-Current already taken into account when the Circuit was designed ?

Are You trying to diagnose a problem that You are experiencing ?

Do You have a Schematic in .jpg, .png, .pdf, or .gif ?
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#### BobTPH

Joined Jun 5, 2013
9,109
am not modeling the battery. I am providing power to a load from the battery. I'm actually trying to model the load.

#### AIBang

Joined Feb 3, 2024
26

#### AIBang

Joined Feb 3, 2024
26
I don't know anything about LTSpice,
but the Simulation-Program that I use will let You simply insert an Ammeter into the Supply-Line,
giving an additional graphic-display of the Current within any time-frame that is selected.

I've always found it to be brutally accurate when all parasitic qualities of
the various Components are properly entered.

Why do You need to know the Inrush-Current ?,
wasn't Inrush-Current already taken into account when the Circuit was designed ?

Are You trying to diagnose a problem that You are experiencing ?

Do You have a Schematic in .jpg, .png, .pdf, or .gif ?
.
.
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The capacitor should not be charged while the FETs are off. However, it charges to 48V here. And I couldn't figure out the reason for the sudden rise and fall of the current.

#### BobTPH

Joined Jun 5, 2013
9,109
electronic device
An electronic device is (generally) not a capacitive load.

#### mahdh

Joined Apr 14, 2024
1
When a capacitor is connected to a circuit, it acts as a load that can store and release electrical energy in the form of an electric field. If you just want to measure the load on a simulation software, add your capacitor (not a battery or other electronic device) and just measure the voltage and current values. Use P=IV too if you need to.