charge battery for 10 hours before use

[bestsystem]

I often see user manuals suggesting users to charge the (lithium ion battery) for 10 hours before use, isn't that pointless since the charging IC will cutoff anyway at 4.2V?

so why do vendors say so? it sound likes a trickle charge method:( in NiCd era.


also some manuals recommend you to charge li-ions full immediately after use, isn't that causes more damage than fully charge only before use:confused:


conspiracy: Vendors wish your battery ages faster and give them more business.:ooo:

 

[lightseeker2009]

And my father stick to the manuals. He leaves a new cellphone on charge for 18 hours even if the screen says battery is full!! I'm also confused by their lack of giving proper instructions

 

[45/70]

If the device has a battery monitoring system, it could be that it takes 10 hrs to "reset" the system. Other than that possibility, I agree, it sounds like something leftover from using NiCd/NiMh batteries. With these though, the initial charge time is/was usually 14-16 hrs, which would provide a forming charge. Perhaps email and ask?

also some manuals recommend you to charge li-ions full immediately after use......

I'll go along with your conspiracy theory on this. I can't think of a better way to sell replacement battery packs! I suppose this also might have something to do with keeping the battery monitoring system calibrated, but I can't really see why. As long as the device is occasionally run down fairly low, this seems to keep most battery monitoring systems in sync.

Dave

 

[TooManyGizmos]

~

For Cell Phone Battery's - you should do as they say - 18 hours .

When it beeps , and says it's charged ... it's NOT really fully charged.

It's just charged enough to USE when it beeps .

18 hours will give it a total- full charge - especially when brand new .

IMHO .... TMG.

~

 

[45/70]

The best way to check would be to take a voltage measurement of the battery at various stages of the charge. When the battery, after resting for a few minutes, reads ~4.20 Volts/cell, you would know when it's actually fully charged.

As I've mentioned frequently in the past however, A fully charged LiCo or LiPo cell rarely is actually 4.20 Volts, even when new, so take this into account. 4.20 Volts (+/- 0.05V) is the maximum allowable voltage for a typical LiCo or LiPo cell. So anything around 4.15V+/cell, I would consider fully charged

Dave

 

[TooManyGizmos]

~

I totally agree with 45/70's reply . Use a meter for best results .

~

 

[Wrend]

Obviously overcharging your cells isn't going to be good for them. Since cell phones use protection circuitry, it hopefully isn't actually overcharging them.

To break-in Li-ion type cells, I have heard of recommendations to do a couple slow charge and discharge cycles on them. Empty is usually considered to be somewhere between 3.2V to 3.6V and full being 4.1 to 4.2.

With hobby LiPos, I know the recommended storage voltage level is 3.85V per cell. It's also only recommended to discharge these LiPos down 80% of their capacity potential to help prolong their cycle life and performance. I also charge both my "Li-ion" and "LiPo" (what my hobby charger calls them) cells to 4.1V since I heard It's supposed to be better for them too.

 

[shadowjk]

My own cellphone's charging system is a bit of a mess. It has 3 battery fuel gauges, one is totally clueless, second is kinda there, and third is accurate but uncalibrated. The second one is presented to the operating system and the user. There's also a charging circuit (of course), and the battery has its own protection circuit, and additionally the phone has its own low-voltage cutoff circuit which can't be bypassed in programming. Low battery warning comes on at 3.5V, normal shutdown takes place between 3.5 and 3.2, depending on the load and the battery health (some sort of half-arsed attempt at tracking internal resistance, I think). Final "forced" shutdown by software at 3.2Volts. Hardware cutoff at 2.8V, and battery protection circuit somewhere around 2.5V.

As for charging, CC/CV @ 950mA to 4.2V, with 50mA cutoff. The system load is connected in parallell with charger, so if system load exceed 50mA, the charger will never terminate. There's also some parasitic resistance, which means that if system load is 900mA, the battery will end up floating/trickle charging at 4.08 Volt.
I don't know about the thresholds and operations of fuel gauges 1 and 2, but number 3 has a datasheet available. It is a coloumb counter, which keeps track of "learned capacity", and resets its counter to the learned capacity whenever it detects battery full, and from there starts counting down. If it has seen an "undisturbed" cycle from full to empty, it updates learned capacity with the recorded capacity from the discharge cycle. The full threshold is something like: Voltage over 4.05V, charge current >0 and <50mA for more than 10 seconds. The user interface works in mysterious ways, and may indicate battery full long before that, or long after that. And as previously mentioned, the battery charger, if there's any system load, which there always is, will terminate after the fuel gauge detects battery full. If it terminates at all.

Considering all this, I'm not quite sure if there's any point at all in following the instructions in the manual. It would be most useful to charge it full, then use it until empty, to get the initial calibration done, but the manual doesn't mention that. And, if you don't follow it, all you get is incorrect battery meter, which might be annoying and give false impressions about battery performance.

 

[bestsystem]

The best way to check would be to take a voltage measurement of the battery at various stages of the charge. When the battery, after resting for a few minutes, reads ~4.20 Volts/cell, you would know when it's actually fully charged.

As I've mentioned frequently in the past however, A fully charged LiCo or LiPo cell rarely is actually 4.20 Volts, even when new, so take this into account. 4.20 Volts (+/- 0.05V) is the maximum allowable voltage for a typical LiCo or LiPo cell. So anything around 4.15V+/cell, I would consider fully charged

Dave

Anyway, fully top up the charge after each use will cause the cell to be full most of the time, which is undesired for li-ion.

I have met some stores and staff fully charge their stocks and sell them slowly, which I don't bother to buy a gadget already has 30% capacity lost.

 

[shadowjk]

Anecdotal battery stories:
5 phone batteries:

Original battery A: Almost Unused, stored "empty" 6 months
Original battery B: used normally in a phone 6 months, approx 1 cycle every second day, so about 60 cycles.
Spare battery C: Spare battery from clone manufacturer 1. Used 60 cycles, then stored fully charged for about 6 months.
Spare battery D: Spare battery from clone manufacturer 1. Unused, fully charged, stored 6 months.
Spare battery E: Spare battery from clone manufacturer 2. Unused, fully charged, stored 6 months.


In terms of their performance, their relative order is: E, D, C, B, A.

A was performing really really badly. B still going strong. C consistently tested 5% lower than D, they were indistinguishable in testing when new. Didn't test them when putting them in storage. E after being stored fully charged for 6 months was performing better than C and D when new.

From this I can only conclude that storing batteries at full charge (4.1 ... 4.2) is much less harmful than at empty (2.5 ... 2.8).


I stopped using C-E after seeing the dramatic difference between A and B, which are original batteries that came with the phone model in question, and manufactured by the same company at the same time, so that I could put some more cycles on B and see how it evolves. It's approaching 300 cycles now, with steady and barely noticeable capacity decline up to cycle 250 or so. After that the decline either accelerated or just became more noticeable, and is at about 83-85% of original capacity now. Age is about 16 months. For comparison, battery A is at 75% of original capacity, and all it ever did was discharge to empty and sit in a desk drawer for 6 months.

Edit: Capacity measurements done by full charge and then discharge down to 3.25V at .5-.7C. At .1C all batteries are within 90% of their nominal capacity, but what good is that if you get low battery alarm the instant you receive a call...