# Is it possible for DC alternator using inverter directl without accu ?

• antonius1
In summary, the conversation is about using a DC alternator to produce AC without using a battery. However, it is not possible due to the difference in the type of DC produced by the alternator and the battery. Suggestions are made to use a small battery to get the alternator started and then let it supply its own power, but it is noted that this does not constitute perpetual motion as the input energy is greater than the output energy. The individual is encouraged to seek advice from engineering forums or those with a good understanding of alternator operations.

#### antonius1

Hello, i am new here, and i hope there is someone here that could help me with this :

## Homework Statement

I have a DC alternator and i want using inverter to make AC.

## Homework Equations

Is there possible without using ACCU ?

## The Attempt at a Solution

I tried directly without using accu, but failed.
I think because DC electric from alternator have a different kind from DC electric from accu.
DC alternator is sinus current, are different with pure DC from accu.

Is there any other reason ? and what should i do to make it working without using ACCU ?

Hi Antonius. Welcome to Physics Forums.

Are you actually trying to build an AC power source for practical use, or is this an academic exercise (perhaps related to a course of study)?

For advice on practical implementation you might find some knowledgeable people over in one of the Engineering forums such as Electrical Engineering or Mechanical Engineering (they have an Automotive section).

My understanding is that the typical modern car alternator unit produces pulsating DC at its output. This is because it's basically an AC generator with built-in diodes for full-wave rectification, hence the pulsating DC output. In a car it's up to the voltage regulator + battery to filter this to DC for use by the car's electronics.

Your inverter is probably not liking the pulsating DC, particularly if it is relying on this DC to power its internal circuitry such as an oscillator to provide the basic AC waveform.

Depending upon how much current you need to draw from the alternator to power your inverter you may need to use a battery, or you might get away with a capacitor bank to provide the filtering and act like a virtual battery.

gneill said:
Hi Antonius. Welcome to Physics Forums.

Are you actually trying to build an AC power source for practical use, or is this an academic exercise (perhaps related to a course of study)?

For advice on practical implementation you might find some knowledgeable people over in one of the Engineering forums such as Electrical Engineering or Mechanical Engineering (they have an Automotive section).

My understanding is that the typical modern car alternator unit produces pulsating DC at its output. This is because it's basically an AC generator with built-in diodes for full-wave rectification, hence the pulsating DC output. In a car it's up to the voltage regulator + battery to filter this to DC for use by the car's electronics.

Your inverter is probably not liking the pulsating DC, particularly if it is relying on this DC to power its internal circuitry such as an oscillator to provide the basic AC waveform.

Depending upon how much current you need to draw from the alternator to power your inverter you may need to use a battery, or you might get away with a capacitor bank to provide the filtering and act like a virtual battery.

Thanks Gneill, actually this is for my own research about the different kind of DC between from alternator and from battery. I will try that forum section too, thx.

I tried using capacitor bank, and failed. It is because the car alternator that i using. I figured out that alternator don't have a strong enough magnet for its rotor, so it's need battery to ignited it.

When i using battery, the output would become pure DC, and without battery the output become pulsating DC. And i cannot find inverter that could accept pulsating DC.

antonius said:
Thanks Gneill, actually this is for my own research about the different kind of DC between from alternator and from battery. I will try that forum section too, thx.

I tried using capacitor bank, and failed. It is because the car alternator that i using. I figured out that alternator don't have a strong enough magnet for its rotor, so it's need battery to ignited it.

When i using battery, the output would become pure DC, and without battery the output become pulsating DC. And i cannot find inverter that could accept pulsating DC.

It sounds like the alternator is using an electromagnet for its field rather than permanent magnets, so it needs the battery to "bootstrap" its operation. Perhaps you can employ a small 12V battery to get things started (rather than a car battery), then the alternator can keep things going and supply its own power for its field. This assumes constant input of mechanical energy to keep the alternator turning under load, of course; no perpetual motion crackpots need apply

I can't think of anything else to offer on a practical front. You'll have to seek out those who have tried similar things with similar equipment, or who have a good understanding of the operating characteristics of this type of alternator.

gneill said:
It sounds like the alternator is using an electromagnet for its field rather than permanent magnets, so it needs the battery to "bootstrap" its operation. Perhaps you can employ a small 12V battery to get things started (rather than a car battery), then the alternator can keep things going and supply its own power for its field. This assumes constant input of mechanical energy to keep the alternator turning under load, of course; no perpetual motion crackpots need apply

I can't think of anything else to offer on a practical front. You'll have to seek out those who have tried similar things with similar equipment, or who have a good understanding of the operating characteristics of this type of alternator.

Yes, i think so, thanks a lot. Of course it is not perpetual motion because input energy it greater than output energy.

## 1. Can a DC alternator be used with an inverter without an accumulator?

Yes, it is possible to use a DC alternator with an inverter directly without an accumulator. However, this setup may not provide a stable power supply and could potentially damage the inverter.

## 2. What are the potential risks of using a DC alternator with an inverter without an accumulator?

The main risk is that the power supply may not be stable, leading to fluctuations in voltage. This can cause damage to the inverter and any devices connected to it. It is also possible for the alternator to be overloaded, resulting in overheating and potentially causing a fire.

## 3. How can I ensure that my DC alternator and inverter setup is safe without an accumulator?

To ensure safety, it is recommended to use a voltage regulator between the alternator and inverter. This will help stabilize the power supply and prevent any potential damage.

## 4. Is it more cost-effective to use a DC alternator with an inverter without an accumulator?

It may seem more cost-effective to omit the use of an accumulator, but the potential risks and damage that could occur may end up costing more in the long run. It is important to consider the safety and stability of the power supply when making this decision.

## 5. Are there any specific types of DC alternators that are better suited for use with an inverter without an accumulator?

There are some DC alternators that are designed specifically for use with inverters, which may be a better option than using a standard alternator. It is important to research and consult with a professional to determine the best option for your specific setup.