How to change the charging time (battery)

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Discussion Overview

The discussion revolves around methods to improve the charging time of a battery connected to a 120V DC source. Participants explore various factors influencing charging efficiency, including internal resistances and battery types, while considering the implications of charging voltage and current.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant suggests that adding components to the circuit could improve charging time, questioning what could be added.
  • Another participant counters that adding components would actually increase charging time, implying that more complexity leads to longer charging durations.
  • A third participant discusses the importance of full cycle efficiency in rechargeable batteries, noting that high charging voltages relative to output voltage can lead to poor efficiency.
  • It is mentioned that most batteries have a maximum charge rate, and increasing voltage is a common method to speed up charging, as seen in smart chargers for model batteries.
  • A participant highlights that the type of rechargeable battery significantly affects the required charging circuit and methods.

Areas of Agreement / Disagreement

Participants express differing views on whether adding components can improve charging time, with some arguing against it. There is also a consensus on the importance of battery type and efficiency, but no clear resolution on the best approach to enhance charging time.

Contextual Notes

The discussion does not resolve the assumptions regarding the specific battery type or the implications of internal resistances on charging efficiency. The relationship between charging voltage and efficiency remains unclear.

quuker
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the source is 120V DC with an internal resistance of 40 Ohms. the battery's emf is 10V with an internal resistance of 1kOhms. what can i add to the circuit to improve the charging time (faster charge)?
 
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Nothing, the more you put in the circuit, the longer the charging time.
 
One of the requirements of a "good" rechargeable battery is the full cycle efficiency. If you had a battery that could recycle 100% of the Coulomb charge, but took 14 volts to charge, with only 12 volts out (like a car battery), that is only 86% efficiency. If you charge with 120 volts, and get 10 volts out, that is a very poor efficiency.
 
Most batteries have a limit on how fast they can be charged, so you need to be careful. The normal way the charge rate is sped up is to increase the voltage. This is how the "smart" chargers for radio control model batteries work, they ramp up to a set amperage by increasing voltage, then periodically shut off the charge current and sample battery voltage.
 
A lot depends on what type of rechargeable battery it is. Different types require different charging circuits.
 

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