Deep cycle lead acid battery charging behaviour?

[kamarn]

Hi,

I use 15V, 1A DC adapter for charging 12V 4.5AH deep cycle lead acid battery with one series diode to decrease the input voltage down to 14.4V, is it the right choice? I want fast charger therefore I use 1A adapter.

Secondly, I want to know the charging behavioUr of lead acid battery in detail, when I switch on my adapter lead acid battery voltages slowly increasing from about 12.9V & reach to 14.4V & then stays at that point,

1. Why the voltages increases from 12.9V while I apply 14.4V on the battery terminals?
2. When the battery terminals voltages reach at 14.4V, does it full charged?

thanks in advance.

 

[tpetar]

No its not ok, lead acid battery in deep discharge state drain high current, and you need to limit current.

Lead acid batteries require voltage and current controlled chargers.

14,2V-14,4V is cycling voltage, and this voltage point is used when battery is deeply discharged (under 50% of capacity).

13,5V-13,8 is float charge voltage, used for float and for recharging battery in semi discharged states.


Best is to read manufacturer datasheet for your battery.

When battery voltage reach 14,4V, charger voltage should be terminated or switched to float charge voltage.

 

[kamarn]

How to limit current?
Any circuit ideas?
What should be the charging current in my case?

 

[tpetar]

You didnt mention manufacturer and battery model number, search information in datasheet.

I use GP1245 12V 4,5Ah datasheet for example.

Based on datasheet recommended maximum charging current is 1,35A. I will say this is for starting charging current, you can keep charging current bellow 1A.

You can use LM317 or similar circuits to limit currents. Search about battery charger circuits.

These batteries usually have life of 3 to 5 years or can have between 200 and 300 cycles, and this only if you apply manufacturer datasheet recommendations for battery usage and charging.