how to find out battery is fully charged?

[mona:)]

hi
i am so greatful for your replys for my my pervious question
i have another question now:
i need a circuit that show how much our battery is charged??
i am in ahurry excuse me if my spelling is not correct...
mona

 

[4pyros]

what battery

 

[colin55]

In most cases you keep charging the battery and you will notice the voltage will rise to a higher value.

 

[crutschow]

Determining the battery charge state depends upon the type of battery.

 

[WTP Pepper]

https://www.mpoweruk.com/chargers.htm

Read and learn.

 

[mona:)]

the battery is lithium one....i want somthing like what is in our cellphones ,sth that shows or alarms battery is charged.

 

[KG4MXV]

Mona
Todays smart phones use pretty complex power management hardware and firmware that keep track of battery performance and it uses that data to give you a calculated estimate of battery life.

Lithium polymer batteries are not really for the novice user.
Unless you use already made chargers for Lipo batteries.
If you can give us some more info like what you are using it for and what kind of load it has we can give you a better answer.
These batteries need to be charged very carefully and discharged also very carefully or you can damage the battery and even make it very unsafe.

 

[mona:)]

the only thing i know is what i said.....(poor me)
those were the only things i have been said.i think they don't know what they realy want .....they only want to make me busy

 

[4pyros]

Yes you should look into power managment chips.

 

[KG4MXV]

Do you need to design a circuit for a class or do you have a have something that is already made.

 

[4pyros]

Sounds like he is working on it for a friend.

the only thing i know is what i said.....(poor me)
those were the only things i have been said.i think they don't know what they realy want .....they only want to make me busy

 

[mona:)]

Do you need to design a circuit for a class or do you have a have something that is already made.

yes i think designing a circuit is the first step then we should try it......

 

[mona:)]

Sounds like he is working on it for a friend.

firstly i am she....and secondly this is a unit of my course to work 300h in a company....and i am doing and this is what company wants...(i am junior student..)

 

[ronv]

I'm no battery expert, but here is what I have seen:

4.19 - 100%
3.99 - 80%
3.86 - 60%
3.77 - 40%
3.70 - 20%

This is with the battery at rest. In other words very low load for about 2 minutes. It will "bounce back" a bit with time.

Look at the LM3914 for the indicator chip.

 

[JMW]

I have always used a scale. A fully charge battery weighs .00000000395% more than a discharged battery.

 

[4pyros]

I have always used a scale. A fully charge battery weighs .00000000395% more than a discharged battery.

How much does a scale with that accuracy cost?

 

[ronsimpson]

I have always used a scale. A fully charge battery weighs .00000000395% more than a discharged battery.

Wow I like that! And all this time I have been counting electrons.

 

[KG4MXV]

no wonder my laptop feels heavier after it has full charged