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[abdoalghareeb]

hi everybody
it is my first time
i need help in my project
i designed a SMPS circuit to regulate the output voltage of wind turbine (output is 12V).
so i need a circuit to charge a deep cycle battery (12V/90A)

 

[Externet]

That SMPS circuit you designed, alter it to present 13.8 V instead of 12 V at the battery terminals and you wll not need any extra battery charger circuit.
Lead-acid batteries are charged with constant voltage.

 

[abdoalghareeb]

ok
but I read to make the battery life longer it is better to charge it 50%

 

[Externet]

To make the battery live longer, read its manufacturer data sheet for any recommended charging voltage and current rate.
If you prefer 50% of whatever be the recommended charging current, you still need the data sheet to find out how much is it.
I would not exceed 10 Amperes if there is no data. If you want 50%, add resistance to the charging wiring so it will never reach 5 Amperes. That should be not a problem with long wires as for a wind turbine
But the voltage has to be per specifications around 13.8 V

 

[(*steve*)]

The voltage depends on charge current and temperature.

It is best that you look up the manufacturers datasheet.

With an intermittent power source it may be difficult to do an optimum charge on the batteries. If you're using a constant voltage you will actually need significantly lower voltage than for normal charging as you will be "float charging"

If this is (or is intended to be) a primary source of power, you may be best off looking for detailed charging instructions to enable you to make the most of the power you have when it is available. It's similar to solar charging, except that you would not want to use a shunt regulator!

These three links should give you plenty to consider.

 

[roltex_rohit123]

never undercharge your battery. I am carrying out my work on battery desulfator and I have noted that the battery needs to be sufficiently chaged to avoid this sulfation. the sulfation occurs when the terminal voltage drops below 11.7 volts. at 50% battery the voltage would be just around 12.3-12.5 volts which is not enough. when under load the voltage will drop and even your backup will be less. you must charge at 13.9-14.2 volts and current of about charge/10 value at the most. less than c0/50 value wont charge the battery fully. the 50% charge is recommended to store the battery and not in cycle use. for example the li-ion are maintained at 40 % charge while in storage. so just make 14.2 v with 13.9 float. good luck

 

[(*steve*)]

sulfation occurs when the terminal voltage drops below 11.7 volts. at 50% battery the voltage would be just around 12.3-12.5 volts which is not enough. when under load the voltage will drop and even your backup will be less. you must charge at 13.9-14.2 volts

That is misinformation. The terminal voltage of a lead-acid battery can easily fall below 11.7 volts under load with absolutely no danger of hard lead sulphate crystals being formed.

The terminal voltage is affected (greatly) by the energy lost in the battery due to internal resistance.

and current of about charge/10 value at the most. less than c0/50 value wont charge the battery fully. the 50% charge is recommended to store the battery and not in cycle use. for example the li-ion are maintained at 40 % charge while in storage. so just make 14.2 v with 13.9 float. good luck

Manufacturers recommendations often state C/8 to C/3 as the maximum charge rates.

Note that C is "capacity", not "charge". Capacity is measured in Ahr, (e.g. a small SLA battery may be 7Ahr, a large battery may be 220 Ahr).

Lead acid batteries can be overcharged, and even rates between C/1000 and C/5000 are not necessarily safe (which puts paid to the argument that you need to charge at > C/50).

I'm not sure that 50% charge is ever recommended for lead acid batteries other than as a limit to discharge. You should always FULLY CHARGE them prior to storage. You simply cannot take recommendations for a vastly different type of battery (LiIon) and assume it applies to another (lead acid).

roltex also ignores the issue of temperature which is significant and important to consider unless you are fortunate to have your batteries in an air-conditioned facility constantly at 20C (that's temperature, not charge) and where the batteries themselves are not heated by charge or discharge rates.