Lithium Ion Charging: Constant Current vs Constant Voltage

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Discussion Overview

The discussion revolves around the charging methods for lithium-ion batteries, specifically comparing constant current and constant voltage approaches. Participants explore the implications of using a constant voltage source for charging and the necessary precautions to ensure battery safety and longevity.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant inquires about the effects of charging a lithium-ion battery with a constant voltage source, suggesting a linear regulator set to 4 or 4.1 volts.
  • Another participant explains that while a voltage source can be used, it is crucial to limit the current to prevent damage to the battery chemistry and for safety reasons.
  • A third participant emphasizes the necessity of using a lithium-ion battery charger controller, outlining the required charging phases: precharge, constant current, and constant voltage, asserting that shortcuts are not advisable.
  • A later reply mentions that discussions on this topic have been closed due to safety concerns, highlighting the specialized nature of safely charging lithium-ion batteries.

Areas of Agreement / Disagreement

Participants generally agree on the importance of using a controlled charging method for lithium-ion batteries, but there is disagreement on the feasibility and safety of using a constant voltage source without proper current limitation.

Contextual Notes

Participants note that charging lithium-ion batteries involves multiple phases and that exceeding the voltage limit can be detrimental. There is an emphasis on safety and the need for specialized knowledge or equipment.

redwan hasan
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Good afternoon.

I was going to make a 4.2v Lithium ion charger circuit, but so far what i have learned is, i will be needing constant current charger, so my question is what will happen if i charge with constant voltage? Like from a regulator maybe a linear one and i give like 4/4.1 volt constant.

Any help will be highly appreciated.
 
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You can charge a lithium-ion battery using a voltage source, but you have to limit the current the battery can draw to protect the battery chemistry from deteriorating (and also for safety reasons). Usually the best way is to charge it first using a current source and then switch to a voltage source at a specified level of battery voltage. You can find many easy to use solutions that handle both stages in a single package, e.g.:
http://www.linear.com/product/LT1512

You can read more here:
http://www.digikey.com/en/articles/techzone/2012/sep/a-designers-guide-to-lithium-battery-charging
 
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You must buy a lithium-ion battery charger controller. Lithium-ion batteries require multiple phases of charging and the voltage across them must never exceed 4.2V. Basically they require A> Precharge, B> Constant Current, C> constant voltage. There are no shortcuts. milesyoung's links are good, especially the digikey link.

http://www.digikey.com/en/articles/techzone/2012/sep/a-designers-guide-to-lithium-battery-charging
 
Last edited by a moderator:
A thread on this topic has just been closed on the basis of safety. Charging lithium ion batteries safely is a specialised business and should be left to the experts - or you need to become one yourself.
In any case, just how expensive are those chargers?
 

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