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Battery charging circuit

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seneda

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I designd a AC-DC converter 12v, 2Amps. connected to battery(12v, 1.3Ah). Once if its charge completely it should be auto turnoff and reccharge again for a period of some time. help me out.
 

Look at the average output voltage the AC-DC converter over a fixed time, when it reaches 12V, cut off a switch in the charging path. To do this, I think, all nodes of the circuit have to be dominantly first order to make sure that the switch is not cut off due to second order ringings.
 

Your 12V converter will be unable to charge the battery further after battery voltage has risen to 12V.

Can you make your converter go up to 14.5 V, at least?
 

BradtheRad said:
Your 12V converter will be unable to charge the battery further after battery voltage has risen to 12V.

Can you make your converter go up to 14.5 V, at least?
Click to expand...

Actually, The battery is connected to a GSM Board always while its charging. so the battery will discharge.once if its charge it should auto cut off.help me
 

I designd a AC-DC converter 12v, 2Amps. connected to battery(12v, 1.3Ah). Once if its charge completely it should be auto turnoff and reccharge again for a period of some time. help me out.
Click to expand...

just use a relay to switch out the battery when its charged up, then have a micro periodically switch it back in to sense if its self discharged a long way. I presume it is lithium battery?. All batteries will self discharge and go flat eventually, even if never used in circuit.
 

First identify which type battery it is and how much current it takes after full charge.
Measure the terminal voltage and current through the battery. When the battery is fully charged it takes less current and the terminal voltage rise 12v.
switch off the MosFET.
 

seneda said:
Once if its charge completely it should be auto turnoff and reccharge again for a period of some time. help me out.
Click to expand...

Sounds like a similar concept as my simple charge controller. I built this in hardware and it successfully charged golf cart batteries from solar PV panels. You might be able to adapt it to suit your purposes.



The charger turns on and off by hysteresis. It does not taper the charge rate.

1) The transistor stays turned on until the battery reaches 14.4V. Then it turns off.

2) The battery is not necessarily fully charged. Its volt level settles downward for the next few minutes.

3) When it drops to 13.4V. The transistor turns on again.

4) The battery receives charge again for a few minutes, then is off.

5) The cycle repeats. Eventually the battery absorbs a full charge.

LED's indicate whether the circuit is idle or charging.

Zener value is not critical. It can be a range of values.
 

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