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lead acid battery charge current

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darla1

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dear all

i am charging lead acid battery using full bridge topology, when i check the output current with resistive load (8A) the waveform is good i.e it is in continues and having ripple current of 2A pk-pk.

next i connected the battery, the current waveform is good upto 3 amps, beyond 3 amps the output current is going to pk pk 16A. the waveform is not good it is going to 1amp to 16 amp.

i did not understand why the system is behaing like this.

can any body explain this problem.

thanks and regards
ramesh
 

The battery is like a huge capacitor. Your charger is not able to supply the required current. Hence the huge ripple. Try putting some large capacitors across the charger.

Cheers

Ravi
 

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    darla1

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ravimarcus said:
The battery is like a huge capacitor. Your charger is not able to supply the required current. Hence the huge ripple. Try putting some large capacitors across the charger.
Click to expand...

thanks Mr ravi

i am using two capacitors in parallel having each 4700uf, i hope this much capacitance is sufficient....

do you think that i need to increase further..

thanks
ramesh
 

darla1 said:
do you think that i need to increase further..
Click to expand...
You will have to ask the charger :-D.

darla1 said:
i am using two capacitors in parallel having each 4700uf, i hope this much capacitance is sufficient
Click to expand...
Check the ripple on an oscilloscope and not with a multimeter. Increase it if necessary. Instead of using 1 large value like 10,000 uF, use small values in parallel. This will further reduce the ESR (Effective Series Resistance) of the capacitors.

Cheers

Ravi
 

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    darla1

    Points: 2
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Check the ripple on an oscilloscope and not with a multimeter. Increase it if necessary. Instead of using 1 large value like 10,000 uF, use small values in parallel. This will further reduce the ESR (Effective Series Resistance) of the capacitors.
Click to expand...

dear ravi

i have checked the wave form with CRO only please have look on my waveform and suggest something...

thanks

ravi
 

darla1 said:
i have checked the wave form with CRO only please have look on my waveform and suggest something...
Click to expand...
The waveform is from a current probe. What is the voltage ripple? If it is 1 or 2 volts / current, it should be ok I presume. To make it smooth, you will need lots of capacitors and it will cost a lot.

Cheers

Ravi
 

To make it smooth, you will need lots of capacitors and it will cost a lot.
Click to expand...

dear Mr Ravi

as per my design i need to get dc output current with pk-pk of 2A, but here i am not getting dc, getting ripple dc from 1 A to 16A, this is not desirable.

if we charge the battry like this the battery life effects.....

thanks
ramesh
 

If you are talking of pk-pk, then it is AC, what is the DC component on the output?
If you are in Bangalore, you can call me. I need to have more info about the problems you are having.

Cheers

Ravi
 

    D

    darla1

    Points: 2
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ravimarcus said:
If you are talking of pk-pk, then it is AC, what is the DC component on the output?
Click to expand...

dear ravi

my dc component is showing only 1A and mean value is 5A then pk-pk is alomost 16A.

i am from hyderabad

thanks
ramesh
 

I am going offline on this topic. I have sent you my contact details. Please email me.

Cheers

Ravi
 

what i understand is that to charge battery first u ned a DC voltage,
what is charging current for battery?
If it is <1.5A then use a LM317 and configure it as current source then u r current thru battery will be constant.

What is current capability of bridge rectifier.

Hope my understanding is correct...
 

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