The Ulka Chemicals

Why the capacity of fresh battery detoriate on charging-discharging cycling ?

Active 4 Replies 630 Views 2021-04-17 08:29:45 Battery

What is the reason for capacity decay on cycling on a fresh battery? Normally it should increase from 1st cycle to 2nd cycle when I check C20 capacity. In around 3-4 cycles it should give a stable C20 capacity.  


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Dr.Ssrma replied
2 Years
It appears the issue is charging.  Batteries are not fully charged in factory Before  despatch.  Reader may like to provide details for solution 
K replied
2 Years

Dear Sir / Madam,

There are lot of reasons for deterioration of Capacity in a new battery. Before we go into the reason for deterioration, first let us understand why capacity of a battery increases during the first couple of cycles.

You are aware that the Positive Active Material is PbO2 and Negative active material is Pb (Spongy Lead). After initial formation / charging, normally the PbO2 present in the plates in general will be between 75 – 85% depending on the process and charging. (In cases, with proper controls and charging algorithm it will be up to 95% also). During initial cycling (Discharging & Charging) the PbO2 & Pb repeatedly gets converted into PbSO4 (lead Sulphate) and then back into their active material state. During this cycling, the Percentage of Active Material PbO2 will slowly increase from 75 / 85% to higher percentage and this in turn will give more capacity. On repeated cycling, the PbO2 and Pb will achieve their highest conversion state and you will find the capacity obtained is stable. This is the reason even IS Specifications say, the batteries have to attain full rated capacity within 10 Charge / Discharge Cycles.

Now, coming to your question of decreasing capacity instead of increasing, there are lot of reasons / factors:

1. Paste Mix (Acid Sp. Gr, Acid Qty, Mixing Temperature, Paste Density, etc.)

2. Curing Process and Free Lead Percentage in the Cured Plates

3. Pickling Process – In case of Tubular Plates (Acid Sp. Gr, Qty per tank, duration of pickling, Acid Temp, etc.)

4. Plate Formation (Acid Sp. Gr, Charging Current Input, Temperature, Duration of Formation, etc)

5. Green Plate Charging (Acid Sp. Gr., Charging Algorithm, Input AH, Charging Duration, Charging Temperature, etc)

The deterioration in the capacity means the plates are not able to recover from their sulphated state to Active material state and it is mainly due to defects in process and process control. Kindly recheck & revalidate the entire manufacturing process & do necessary corrections. This will solve your issue.


Arvind replied
2 Years
better share the charging-discharging data for better assessment of the problem.
K replied
2 Years
Can you share the test reports for various cycles. Without full details it will be difficult to give any solution / suggestion 

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