Is it necessary to charge a Li-ion battery about 6-7 hours in its initial charging..?

[pradeep_k_b]

Is there any importance with the initial charging of Li-ion battery?..Many of the technical blogs and website recommended like "You should first initially charge your cellphone for straight 6-7 hours for longer battery back up and life".Is there any scientific background for this???...If we consider NiCd,it is affected by the problems like "memory effect",but Li-ion is absolutely free from this bad effect,so I think the "conditioning" is unnecessary for Li-ion...Then what is the importance of this initial charging???

 

[Genovator]

6-7Hrs doesn't matters. The important thing is that you shouldn't start using the battery from its half charge. When you buy a new device or a battery, they doesn't comes with 100% charge. Batteries should be stored in around 60% of charge when you are not using. Also there is self discharge of cells. Any new battery should be first charged to its full 100% then it should be used, otherwise its Ah (battery capacity) will be reduced. If your battery is fully charged in 3 hrs, then start using it. You can refer to:
https://en.wikipedia.org/wiki/Li-Ion

 

[pradeep_k_b]

Thank you....but if we charge a 3.7v li-ion for long time,then we can see that it will exceed 3.7v,and it will charge up to 4v or 4.1v...what is reason for that?

 

[jeffrey samuel]

charging a new battery for a good period of time is efficient as it prolongs life of the battery

 

[pradeep_k_b]

If you dont mind pls tell me the reason too?how it helps to increase battery life?

 

[Genovator]

but if we charge a 3.7v li-ion for long time,then we can see that it will exceed 3.7v,and it will charge up to 4v or 4.1v...what is reason for that?

That 4.1V is the Open circuit voltage. About this I don't know very much. I can only say that it is due to the presence of excessive charge in the battery. It drops to few milivolt after removing from charging. Maybe due to heavy electrolytic movement or something else. It is affected by temperature, and the specific gravity of the electrolyte at full charge.

 

[jeffrey samuel]

I don't think the open ckt voltage plays a dominant role in the actual voltage op of the battery in load

 

[Genovator]

I think he is asking about the terminal voltage, which even exceeds than its rated value when there is no load connected.

 

[pradeep_k_b]

Yeah..but i didn't get the real answer for my question yet..what is the importance of this 6-7hour initial charging?....a lot of website and blogs said it is neccessary,but didn't get a clear idea about this.

 

[FoxyRick]

I do not believe that the 'suggested' initial 6-7 hours charge is needed. Nothing that I have ever read about LiIon or LiPoly chemistry requires that, once the initial charge is done during manufacture. Personally, I have used a lot of LiIon cells over the years and have never noticed any benefit from this.

The industry says things to consumers for many reasons, most often not the ones that we, as engineers, would be interested in. Some possible reasons for this one are:

1. To allow a smart battery monitor (in the battery or equipment) to start usage monitoring from a known, full charge. This is a legitimate reason.
2. Because someone in marketing said, "We always put that in the instructions". This is a stupid reason, but very common!
3. So that consumers don't get annoyed when their new gadget runs out of power 20 minutes after they leave the house. This reason accounts for stupid users, who seem in endless supply.

Some LiIon facts:

1. The full charge voltage is around 4.2V, determined by the cut-off point of the charger. Putting a little extra in, gets more capacity, at the risk of overcharging the cell if the regulation is inaccurate.
2. The cell's voltage drops continually throughout discharge, and should not be allowed to go below about 3.0V. 3.7V is roughly the 'average' voltage. Contrast this with NiMH which keeps an almost constant voltage until nearly exhausted.
3. If a cell's voltage is allowed to drop too low, due to abuse or self-discharge, then it can start to grow metallic dendrites which can eventually short the cell. Once started to grow, these can continue even if the cell is not abused further, leading to 'surprise' failure.
4. Cells keep their charge best (lowest self-discharge) at around 50% charge (hence that is how they leave the factory). At full charge they self-discharge more quickly.

 

[pradeep_k_b]

Thank you very...really helpful..

 

[phatcreators]

can we have a circuit that easily disconnect the batteries or stop their charging ?

Because when we plug in the cells or batteries in the charger and plug in the charger in the power outlet then how can we get to know that the cells or batteries are charged up to 100 % ?

 

[FoxyRick]

Any 'good' charger or charging circuit (usually based around an automatic IC) should terminate the charge properly at a safe 100%* level; it is essential for LiIon.

*based on its designed termination voltage. Cells can be pushed to the maximum voltage to maximise capacity, but at the risk of overcharging. It's a balance between safety and cell life, and capacity.

 

[krixen]

the lithium needs to form on the electrodes from the first charge, it is necessary for a longer charge on the first charge of a battery

 

[pradeep_k_b]

Krixen,Can you explain?

 

[FoxyRick]

the lithium needs to form on the electrodes from the first charge, it is necessary for a longer charge on the first charge of a battery

Lithium ions migrate to the graphite anode during charging, whether it's the first charge or not. As far as I know the lithium does not 'form' on the electrode - it is intercalated into the graphite structure. It is also removed again during discharge and there is a net migration of lithium ions back into the cathode. Do you have a reference for what you say?

Are you thinking of the formation of the solid electrolyte interphase, which is formed during the initial (manufacturing) charge?

 

[jeffrey samuel]

The factories ensure that the initial layer is formed before being brought to the market

 

[tpetar]

First/second cycle of lithium based battery giving battery full capacity, and this is not forming process.