I want to know when charging a battery whether the charger reduces its current input as the battery reaches 80 percent charge, because it takes longer to charge the battery due to the charge curve.

Or is the internal resistance of the battery causing more heat to be dissipated whilst charging past 80 percent?

Thought I'd also clear up that it's a phone charger with a lithium ion battery. I'd also be interested in this for a lead acid battery and charger.

Thanks in advance.


closed as unclear what you're asking by Andy aka, Voltage Spike, winny, DoxyLover, MCG Jun 1 '18 at 10:29

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    \$\begingroup\$ Which battery chemistry are we talking about? \$\endgroup\$ – valerio_new May 30 '18 at 11:13
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    \$\begingroup\$ There is NO generic charger and NO generic battery. \$\endgroup\$ – Andy aka May 30 '18 at 11:13
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    \$\begingroup\$ What kind of battery? What kind of charger? \$\endgroup\$ – MCG May 30 '18 at 11:14
  • \$\begingroup\$ Hi its lithium or lead acid just a phone or lead acid battery charger. \$\endgroup\$ – 1byanymeans May 30 '18 at 11:15
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    \$\begingroup\$ "just a phone or lead acid battery charger" tells us nothing, since there is no single technique used for either (although there is basically only one technique for lithium in wide use for good chargers - but there are a lot of crappy ones on the market). \$\endgroup\$ – WhatRoughBeast May 30 '18 at 13:09

Chargers for lithium and lead-acid batteries typically charge with a constant current until the battery voltage reaches a certain level, something like 2.4V per cell for lead-acid and 3.7V per cell for LiPo. Once this maximum voltage has been reached the charger switches to a constant voltage mode. Charging continues until the current falls below some predetermined level where the charger considers the battery to be fully charged. So, the charging algorithm really doesn't care about the "state of charge".

Having said that, no one can possibly know how any particular charger works if you don't provide a data sheet for it.


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