transisor sl100

[mvs sarma]

It is NOT the battery but the charger controller that has/would have the facility to stop further charging.

 

[domz15]

and that charger controller is inside the cellphone?

 

[mvs sarma]

For example, please see the microchip device

 

[domz15]

i can't understand it

 

[audioguru]

Why don't you read about Lithium batteries at The Battery University (on the internet)?????

A lithium battery charger requires a circuit that detects when it is fully charged. The detection circuit must stop over-charging to prevent the battery from catching on fire.

 

[Ziddik]

hi domz..

Here is a typical charger circuit without using any transistor but a regulator ic for external DC power IN

**broken link removed**

 

[audioguru]

The charger that Ziddik posted is for an old fashioned Ni-Cad battery and will cause a modern Lithium battery to explode or catch on fire.

 

[Ziddik]

i use this circuit to charge a 3.7v cellphone battery and it works perfectly

 

[domz15]

is that circuit automatically cut off the charging process when fully charged?

 

[alec_t]

No! It doesn't prevent over-charging, with the risks that Audioguru has pointed out plus the likelihood of a very short battery life. DON'T USE IT if your phone has a lithium battery (even if Ziddik does)!!.

 

[audioguru]

Ziddik never said what is the type of battery in his cell phone. Lead-acid? Ni-Cad? Ni-MH? Lithium?

Don't all modern Lithium cell phone batteries have a 3rd contact for the thermistor inside?
Ziddik's "charger" does not use it.

 

[Ziddik]

I use nokia bl-5c n will take 2 or 3 hours to fully charge my battery, I use it for a long time n still my battery is good..

 

[mvs sarma]

there are some chargers in society sold by China( see link https://www.amazon.com/Universal-Mobile-Phone-Battery-Charger/dp/B001AHU6QU )
These have two adjustable leads and nothing more other than mains connecting pins on the other side
the clip is pressed and battery with proper polarity is placed inside.
For universality, the pins are to be adjusted to make contact with battery terminals.
Audio guru may wonder that this item is sold on amazon.com

so the thermistor etc are not cared, even though it was incorporated for safety.

As such perhaps Ziddik might also be using his charger.

No doubt that these chargers are highly dangerous and the battery might explode.

yes we heard cases of Chinese batteries sold as replacements exploding.

 

[audioguru]

There are tutorials about properly charging batteries on the internet. One of the best ones is at https://batteryuniversity.com/

 

[domz15]

My professor changed my project, She wants me to have a cellphone battery indicator instead of automatic cut-off.. Do you know a circuit of battery inidicator?

 

[audioguru]

What do you want to indicate? The battery temperature? The battery voltage?

 

[crutschow]

My professor changed my project, She wants me to have a cellphone battery indicator instead of automatic cut-off.. Do you know a circuit of battery indicator?

There is no way to accurately determine the charge on a lithium battery, expect by monitoring the amount of charge into and out of the battery, since Li battery voltage is not a reliable indicator of its state of charge. There are ICs designed to monitor the battery charge flow just for that purpose.

 

[audioguru]

Since all cell phones have a battery charger circuit inside then you can make an indicator that the lithium battery is fully charged by monitoring its charging current. When the battery is fully charged then the charger IC disconnects the battery from the charger so the charging current becomes zero.

 

[domz15]

what IC it is?

 

[audioguru]

Almost every semiconductor manufacturer makes a lithium battery charger IC. But I don't know which manufacturers are available in your country. Maxim make some good ones.