Battery charger fundamentals: Watts, Volts, Amps

Summary

In this video, the presenter discusses the need for a more powerful battery charger due to the limitations of their current 650-watt charger, which struggles to efficiently charge high-capacity batteries at their maximum potential. They introduce the fundamentals of battery charger specifications, using analogies to explain the relationship between watts, volts, and amps. The video aims to educate viewers on how to choose a charger that can handle higher power demands for faster charging, while also touching on the importance of efficiency and heat dissipation in electrical systems.

Takeaways

• 🔋 The speaker is considering a new battery charger due to the limitations of their current 650 watt charger which doesn't charge quickly enough.
• 🔌 Understanding the relationship between Watts, Volts, and Amps is crucial for selecting the right battery charger.
• 💧 The analogy of water pressure and flow is used to explain the concepts of Volts and Amps, with high pressure corresponding to high voltage and high flow to high amperage.
• 🔩 The script uses the example of a water jet cutter for high voltage, low amperage and a drainage culvert for low voltage, high amperage scenarios.
• 🛠 Watts represent the capability of electricity to do work, while amps contribute to heat generation, which is important in electrical systems.
• ⚡ Higher voltage systems can output the same amount of power with less current, resulting in less heat dissipation, which is beneficial for safety and efficiency.
• 🔌 The script explains that in electrical systems, especially in countries with different voltage standards, the balance between volts and amps affects the heat generated and the thickness of wires needed.
• 🔄 Battery chargers are essentially voltage converters with an input and output voltage, and the efficiency of these chargers is a key factor in their performance.
• 📉 The efficiency of a battery charger can vary based on the output current and input voltage, and it's essential to check the datasheet for specific details.
• 🚫 The script warns against the use of linear regulators for large input voltage differences due to significant heat generation and inefficiency.
• 📈 The video script promises a follow-up video with a detailed rundown of battery chargers the speaker has been considering, indicating a series of informative content to come.

Q & A

What is the main issue the speaker is facing with their current 650-watt charger?

The speaker's current 650-watt charger is not able to charge their 1,300mAh 4s batteries quickly enough, barely reaching half the C-rate, even though the batteries can charge at 1C and potentially even 2 or 3C.

What is the purpose of the speaker making a video about their charger dilemma?

The speaker makes a video to share their thoughts and considerations about getting a more powerful charger, as they have found that their audience appreciates such content, as evidenced by their previous video about a flight control board.

What is the fundamental relationship that the speaker explains is essential to understand for battery charger specifications?

The fundamental relationship is Watts equals Volts times Amps (W = V x A), which is essential for understanding the power capacity and performance of a battery charger.

How does the speaker suggest thinking about Volts and Amps in terms of an analogy?

The speaker suggests thinking of Volts as water pressure and Amps as water flow rate, using the analogy of a high-pressure water jet cutter and a drainage culvert to illustrate high voltage-low amperage and low voltage-high amperage scenarios, respectively.

What does the speaker mean by 'Watts do work, Amps make heat'?

The speaker is explaining that Watts measure the capability of electricity to do work, while Amps are related to the amount of heat generated in a circuit, which is a function of the current (amps) and resistance in the circuit.

Why might someone choose a higher voltage system for their electrical needs?

A higher voltage system can provide the same amount of power (Watts) with lower amperage, which results in less heat dissipation and can be safer and more efficient for certain applications.

What is the significance of the equation 'Watts in equals Watts out times efficiency' in the context of battery chargers?

This equation highlights that the power input to a battery charger must equal the power output, adjusted by the charger's efficiency. It's crucial for understanding the maximum charging capacity and the heat dissipation of the charger.

Why does the speaker mention that higher input voltage for a battery charger can be beneficial?

A higher input voltage for a battery charger means that for a fixed output, the charger will draw less current, resulting in less heat dissipation and potentially higher efficiency.

What is the difference between a switched mode regulator and a linear regulator in terms of heat dissipation?

A switched mode regulator is more efficient and dissipates less heat compared to a linear regulator, which drops voltage by converting power to heat, thus dissipating more heat as the difference between input and output voltage increases.

What advice does the speaker give regarding the use of linear regulators?

The speaker advises that linear regulators should be used in the right place and cautions against using them when there is a large input voltage and a low output voltage, as this would result in a lot of wasted power as heat.