Minimize charging time of a battery

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Discussion Overview

The discussion revolves around improving the charging time of a lithium-ion battery using a 120V DC source. Participants explore the implications of the battery's internal resistance and the safety considerations associated with charging lithium-ion batteries.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant inquires about what can be added to the circuit to enhance charging time, given the specifications of the battery and the power source.
  • Another participant emphasizes the importance of knowing the type of battery and its discharge level, suggesting that different battery types have varying charging requirements.
  • A participant identifies the battery as a lithium-ion type, which is noted to have specific and complex charging needs.
  • Concerns are raised regarding the safety of charging lithium-ion batteries, highlighting risks such as fire hazards and the need for proper charging equipment.
  • One participant questions the provided internal resistance value of the battery, suggesting it seems excessively high.
  • Another participant points out that charging a 10V battery with a 120V source is unconventional and recommends using a supply with a voltage slightly above 10V, along with necessary safety features.
  • There is confusion about the battery's voltage, as lithium-ion cells typically output around 3.6-3.7 volts, leading to questions about the 10V figure mentioned.
  • A participant queries the source of the 120V DC, noting that rectifying 120V AC would yield a higher voltage of approximately 168 volts.
  • One participant suggests purchasing a proper charger designed for lithium-ion batteries to avoid safety risks.

Areas of Agreement / Disagreement

Participants express differing views on the appropriateness of the charging setup and the safety of the proposed method. There is no consensus on the best approach to improve charging time or the validity of the internal resistance value provided.

Contextual Notes

Participants highlight potential limitations regarding the assumptions made about the battery's specifications and the charging method. The discussion reflects uncertainty about the voltage levels and safety measures required for charging lithium-ion batteries.

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?
 
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Different batteries types have different charging requirements. What type are you recharging, and what is it, and from what level of discharge is it being charged from?
 
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it's an lithium ion battery.
 
Lithium is very tricky to recharge. Rechargers on the market rely upon microcontrollers to quick charge, and then to top-off. Lithium batteries tend to be a fire hazard if charged too quickly or are overcharged. They sell little fire supressing bags to recharge them into keep you from burning down your house due to a mishap. They can explode in a very exothermic fireball.

1) I'm suspicous of the 1K Ohm internal resistance value you've given. It sounds way too high.

2) One wouldn't normally charge a ~10 volt battery with 120 volts. To trickle charge you would use some supply, nominally greater than 10 volts, and include a limiting resistor, and cut-off voltage control for lithium.

3) Lithium ion cells output 3.6-3.7 volts. Where does the 10 volts come from?

4) Where do you get 120 volts DC? Rectification of the 120 VAC line gives you 168 volts.

5) Why don't you purchase a charger that won't burn down your mother's house?
 
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