| Author |
Message |
bean123
Joined: 18 Aug 2009
Posts: 5
Location: china
|
 18 Aug 2009 4:02 charging lithium ion battery |
|
|
|
|
Hi,
My battery charging circult has only constant Current, no constant Voltage method,
and the constant current is 1A.
When the battery voltage arrive the cutting voltage 4.2V, the circult cut off. but the battery voltage descent from 4.2V to 4.11V within about 4 minute.
So the battery can't arrive the voltage (4.2V) I want to get.
And when the constant Current is smaller ,the battry voltage is higher. For instance, when the constant current is 400mA, the V get about 4.16V.
How can I make the Voltage arrive 4.2V?
Someone tell me that the li-ion battery has a long chemical response time. and this is the reason.
Is that right?
And please give me the sollution.
I need to design the canstant voltage charging???
Thanks
|
|
| Back to top |
|
 |
IanP
Joined: 05 Oct 2004
Posts: 6492
Helped: 1542
Location: West Coast
|
18 Aug 2009 4:26 battery cant charge |
|
|
|
|
You have to follow the basic charging algorithm, that is to charge at constant current (0.2 C to 0.7 C depending on manufacturer) until the battery reaches 4.2 Vpc (volts per cell), and hold the voltage at 4.2 volts until the charge current has dropped to 10% of the initial charge rate ..
The termination condition is the drop in charge current to 10% ..
In other word, your charger has to be constant current, then constant voltage with current sense and for safety reason you should also include a timer ..
Rgds,
IanP
|
|
| Back to top |
|
|
bean123
Joined: 18 Aug 2009
Posts: 5
Location: china
|
18 Aug 2009 5:03 is it bad to fully charge li-ion |
|
|
|
|
thank you for your answer.
your mean is that the constant voltage charging is necessary for li-ion battery charging?
I also trend to agree with the answer.
|
|
| Back to top |
|
|
Google
AdSense
|
18 Aug 2009 5:03 Ads |
|
|
|
|
|
|
| Back to top |
|
|
bobcat1
Joined: 10 Jul 2002
Posts: 1118
Helped: 48
|
22 Aug 2009 7:22 charge a lion battery |
|
|
|
|
HI
Simply use a charger IC - since charging LI-ION battary might be denger - battery can explode
Also don't consume current from battery while charging it - use a switch to disconnect the battery from load when charging
All the best
Bobi
|
|
| Back to top |
|
|
