Continue to Site

Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

6v, 4.2mAh Battery charger circuit problem

Status
Not open for further replies.

softlab

New Member
Dear All,

I have made a circuit based on L200 IC for charging 6v, 4.2Ah Lead Acid Battery. Just I want to know whether the current stops automatically if Battery is fully charged or not. Also, I like to show RED LED when the battery goes below specified voltage (say 5.2v) and to show GREEN LED if the battery fully charged and disconnect the battery from charger circuit. Can you pl help me?

The circuit I used:

R1 - 820 ohms
R2 - 4.7k
R3 - 0.5 ohms 5W



Advance thanks.
 

Attachments

  • SP32-20110529-115935.gif
    SP32-20110529-115935.gif
    9 KB · Views: 523
Last edited:
Are you sure it's a 4.2mAh battery?

The lowest capacity I know of lead-acid-batteries 2Ah.

Boncuk
 
Last edited:
Thanks Boncuk for the response to my queries. Sorry Sorry. My battery is 4.2Ah lead acid (sealed) .
 
The circuit you show will simply charge the battery to its output voltage setting and then maintain that voltage. The charging current at that point will be whatever the battery will take when it is charged to that voltage. It will not stop charging.

If you want the charger to turn off then you will need to add some type of comparator circuit to detect the voltage and current and shut it off at the desired charge point.
 
Thanks for your response crutschow. Help with any schematic will be appreciated. I measured the charging current at various voltages while charging circuit connected to the battery. The amps decreases with proportional to the voltage increases. At the Battery voltage at 6.70 approx, no current flows into the battery. I guess the charging circuit stop charging the battery. Is that correct?
 
I measured the charging current at various voltages while charging circuit connected to the battery. The amps decreases with proportional to the voltage increases. At the Battery voltage at 6.70 approx, no current flows into the battery. I guess the charging circuit stop charging the battery. Is that correct?
Yes, as the charge voltage approaches the open circuit voltage of the battery, the charging current will decrease. When they are equal no current flows.
 
Hi,

Oh it's a 4 Ahr battery, not a 4mAr battery...this thread makes much more sense now.

Today i was working with a 70mAr battery (yes that was really 70mAr) and even that is small.
 
Yes, as the charge voltage approaches the open circuit voltage of the battery, the charging current will decrease. When they are equal no current flows.

I have also made the circuit based on UA741 IC for low/high voltage monitoring. It works fine. What I want to know is that whether Should I use that separate circuit to show the LED (for LOW and HIGH) to the user or Is that possible to use the same charging circuit itself (i.e. No need to use UA741 IC voltage monitor circuit).

thanks
 
Hi softlab,

here's your circuit.

Boncuk
 

Attachments

  • L200-CHARGER-SCH.gif
    L200-CHARGER-SCH.gif
    15.3 KB · Views: 7,247
  • L200-CHARGER-BRD.gif
    L200-CHARGER-BRD.gif
    32.9 KB · Views: 2,924
Great Great Thanks Boncuk. I'll go with this circuit and test and update you on Monday. Once again Thanks a lot.
 
Status
Not open for further replies.

Latest threads

New Articles From Microcontroller Tips

Back
Top