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Laptop charging principles

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Jane11

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If I plug in a charger, what voltage should I measure coming to battery from charger?100% of the output voltage of the charger?Or less?

Is voltage from the charger coming through any charger controller on mainboard?


If I follow this procedure:
I Remove battery
Connect a charger
Measure voltage on the connector and there is voltage( for a short time),so the path charger --> battery is OK
Connect the battery
Yet, no charging even though there is a voltage on the battery connector( but not sure if it is coming from the battery or from the charger)

Does it mean the charging controller is faulty? or software problem?


ANd what is a function of the charging controller on the mainboard?

Thank you for explanation
 

large_ghostman

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Its likely the battery, most have circuitry inside inside the battery. As too what this does depends on the laptop and battery make, some are pretty complex. Does the laptop work ok without the battery? if the problem is simply the battery wont charge, then my guess is its the battery. Most being lithium ion or similar, often have a protection circuit that will cut charging when the bat has had it. My samsung wont charge after 2 years as it tells you on screen its time to replace the £200 battery! Yeah right, I ebay a cheap clone :D.
 

audioguru

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Most Helpful Member
A "charger" for a laptop is not an actual charger, instead it is the power supply for the charger circuit inside the laptop. The Lithium battery is charged from the charger circuit, not directly from the power supply.
The battery probably has a protection circuit to prevent an explosion if a stupid person tries to charge it without the charger circuit.

The battery for a laptop has at least 3 connections, one is for a temperature sensor. How do you know which connector pin is +, - or the temp sensor and how do you know how much voltage and current for charging? How do you know when the battery is fully charged when the charging must be disconnected?

Do not buy a battery on ebay because many are fakes or are assembled with worn out battery cells.
 

large_ghostman

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On the Samsung the battery has 5 connections, what are the other 2 used for?? The battery (original) also has a lcd readout on it.
 

audioguru

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A Lithium battery is supposed to be charged by a "balanced" charger that measures and charges each cell separately so there is a wire between each pair of cells. I have never seen a laptop battery with a readout on it.
 

large_ghostman

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A Lithium battery is supposed to be charged by a "balanced" charger that measures and charges each cell separately so there is a wire between each pair of cells. I have never seen a laptop battery with a readout on it.
I suppose its just a fancy version of the laptop batteries with a column of leds that light to show the "quality of life" left in the battery. Yes quality of life is how the manual describes it :D.
 

Jane11

Member
Thank you ALL for the replies.
So if I understand well now,
voltage( current) has this charging path:
mains charger --> the laptop charger circuit --> battery.
So, a question is: How to find out that the reason for NOT charging is the laptop charge circuit fault.
What steps to take to repair the charger circuit ?

I think that a similar voltage path , the same principles, are the same for various devices including cell phones.
From my experience regarding cell phones , I had mobile that indicated charging, yet not charging the battery in fact( only pretending charging).
How it can be then?
 

Diver300

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A Lithium battery is supposed to be charged by a "balanced" charger that measures and charges each cell separately so there is a wire between each pair of cells. I have never seen a laptop battery with a readout on it.
https://www.amazon.co.uk/Shinntto-Battery-Apple-Macbook-10400MAH/dp/B007F9D57E
An original one of those is powering me writing this post.
The big grey round bit is the foot. The row of 5 dots is the power gauge and the ring at the other end of the 5 dots is the button that activates the power gauge. It works without the battery being in a computer.
 
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