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Minimize charging time of a battery

  1. Apr 20, 2009 #1
    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?
     
  2. jcsd
  3. Apr 20, 2009 #2
    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?
     
    Last edited: Apr 20, 2009
  4. Apr 20, 2009 #3
    it's an lithium ion battery.
     
  5. Apr 20, 2009 #4
    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 in to 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?
     
    Last edited: Apr 20, 2009
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