Why Must Charge Battery for 8 Hrs?

[sulhan]

An interesting thread...

I used to work on charging systems for digital camera and did intensive study on different battery chemistries - as we were designing in camera battery chargers the accepts multi-chemistry AA batteries and also dedicated square battery packs for slim cameras.

On the part of the lithium Ion batteries, they are usually voltage level sensed on chip. Once the voltage level across the battery terminal is reached, then the current pumping will cease.

Problems will comes when you have resistances along the path like bad contacts, oxidised contacts(resistances) that might just "reflect" wrong true battery level which then shut off the voltage prematurely - notice the amount of work done on battery contacts design to intentionally scratch the surface off the"oxidation".

So you will get batteries that are not getting full charge even when battery chargers stops charging the Li-Ions.

So best is to keep the contacts clean and "rust" free.

 

[JPLim]

All Lithium chemistry batteries will tend to do that if you overcharge them, that's why it's important to use the correct charger.
I'm not sure of the chemistry behind it.
A modeler who has overcharged his model batteries several times (using home built 'fast' chargers) says they tend to still work afterwards but their life was shorter.

A new generation charger for Lithium batteries consists of two charging modes.
First, it starts with constant current charging for fast charging the batteries.
When the batteries voltage reach about said 80% of the desired voltage level,
it will change from constant current charging mode to constant voltage charging mode.
The constant voltage charging mode is slower and this is to ensure that the safety as Lithium battery is quite dangerous if do not handlle it properly.
When the Lithium reachs the desired value,
the charger will stop to charge the batteries.
That's y it is advisable to use the original charger for that company batteries as different company batteries might have different characteristic.

 

[Kongo]

In that case, maybe I should dig out my Caig Progold solution to clean the contacts of my charger once in a while.. hehe

http://store.caig.com/s.nl/sc.2/category.292/.f

Used to use these to clean my hifi system contacts when I was still an audiophile few years back, after every cleaning the system will sounds much more energetic like on steriods.. :bsmilie:

An interesting thread...

I used to work on charging systems for digital camera and did intensive study on different battery chemistries - as we were designing in camera battery chargers the accepts multi-chemistry AA batteries and also dedicated square battery packs for slim cameras.

On the part of the lithium Ion batteries, they are usually voltage level sensed on chip. Once the voltage level across the battery terminal is reached, then the current pumping will cease.

Problems will comes when you have resistances along the path like bad contacts, oxidised contacts(resistances) that might just "reflect" wrong true battery level which then shut off the voltage prematurely - notice the amount of work done on battery contacts design to intentionally scratch the surface off the"oxidation".

So you will get batteries that are not getting full charge even when battery chargers stops charging the Li-Ions.

So best is to keep the contacts clean and "rust" free.

 

[spheredome]

You will see this in user guides for electronic item with rechargeable battery. The reason is to set the item into operating with optimal baseline performance, including the battery, aka first impression.

Users can sometimes be ignorance or impatience, so charge for a few mins, start using and later complain short lifespan and flood service centre with calls. However there are real situations where the brand new battery is faulty which discharged by itself or not able to keep full power. Without full charge, one cannot determine the baseline.

Why 8 or 12 hrs is because this is a safe estimate if you are just quoting, else user will be asking "why is the item still charging, it is already pass 5 hrs?" Most camera charger will switch off when batt is full. However there will be non intelligent charger (inbuild or external) out there which damage battery if left too long. So these becomes self applied safety rules.

So the verdict is, YES you need to charge the battery for X hours on the first purchase use. Remember, rechargeable don't just apply to AA/AAA situation only. Phones, PDA, notebooks, vacuum cleaner, lantern, alarms are out there too.

Howcome all the salesman advice us to charge the battery for 8 hours during the first charge?
What's the rationale behind this? I've never seen this mentioned in any of the user manual.

 

[Lightworkz]

In that case, maybe I should dig out my Caig Progold solution to clean the contacts of my charger once in a while.. hehe

http://store.caig.com/s.nl/sc.2/category.292/.f

Used to use these to clean my hifi system contacts when I was still an audiophile few years back, after every cleaning the system will sounds much more energetic like on steriods.. :bsmilie:

Hi Kongo, is this available in any local stores? I went Adelphi and ask a few hi-fi stores, they don't have it.

 

[Canew]

I just want to affirm that what he has said regarding charge cycles is correct.
I think I read that in the Macbook's manual. :thumbsup:

Thanks for the re-affirmation, WuffRuff.

 

[ninelives]

google it, like others mentioned, ni-cad got memory effect, li-ion does not. and it is also not healthty to keep charging and discharging your li-ion battery.

goole it...

 

[afbug]

I've faithfully follow the rule of 8 hrs 1st charge from nickel-metal to lithium batts and so far it works as promised. So its simple, if it ain't broken, don't fix it.

 

[bartman]

I've also find it strange that salesman still continue to advice customer to charge the battery for long hours on first initial charge even today. Consumer devices, example mobile phones, uses Lithium-ion batteries and these batteries have built in battery management controllers. Changing would typically stop when the battery reaches it's predefined level. Modern battery chargers (will come with some kind of over charging protection also. Even if you leave the charger on for 20 hrs, it will still cut off once the battery is fully charged and not continue to charge non-stop for 20hrs.

Initially for lithium-ion batteries(consumer electronics ones), i did not know there is a tiny strip of circuit board built into the battery unit until one of my colleague dismantled one and showed it to me. The circuit board looks something like this :

I later came across one of Maxim's battery management IC datasheet and browsed through it. It mentioned that "overcharging or overdischarging a Li+ cell can cause it to explode", thus i believe all lithium-ion battery will come with some kind of built-in over charging protection and there is no way charging longer hour will have any benefit. The charging protection circuit will eventually stop charging once the battery is fully charged. Below is a sentence extracted from Maxim Battery Management Application Notes :

Lithium-Ion Safety
Because overcharging or overdischarging a Li+ cell can cause it to explode and injure people, safety is a major concern when handling this type of storage cell. As a result, commercial Li+ battery packs contain a protection circuit, such as the DS2720 (Figure 7). The DS2720 provides all the electronic safety functions required for applications that involve rechargeable Li+ batteries: protection for the battery during charge, protection for the circuit against excess current flow, and maximizing battery life by limiting the level of cell depletion.

For the full application notes click here
Nickel-cadmium (NiCd), nickel-metal-hydride (NiMH), and lithium-ion (Li+) battery chemistries are also discussed in the application note.

For me, once the indicators says charging completed, i will just switch off the charger. There is no point in leave it running "idle" since it has completed it's task.

So, to answer your question of whether to charge your battery for 8 hrs, the answer really depends on how long your charger takes to inform you that charging is completed.

Hope this helps......

 

[Kongo]

You can try New Disc Village on the 3rd floor, I vaguely remember that they hv it.

I bought 2 bottles from the distributor somewhere in Kallang many years back, still got plenty left until now.. can use very long one.. but cant remeber the name already.

edit: ok, just searched the website, the distributor is Spire technologies
http://store.caig.com/s.nl/sc.15/category.112/ctype.SS/SS.112/.f
http://www.spire.com.sg/

Tel: 63915310

Hi Kongo, is this available in any local stores? I went Adelphi and ask a few hi-fi stores, they don't have it.

 

[ddwmk2002]

To get a better understanding on the different type of battery, read the link below... You won't get a PhD after digesting all the info... but good enuff to speak like an expert on surface...:bsmilie:

http://www.batteryuniversity.com/

 

[redstorm]

I've also find it strange that salesman still continue to advice customer to charge the battery for long hours on first initial charge even today. Consumer devices, example mobile phones, uses Lithium-ion batteries and these batteries have built in battery management controllers. Changing would typically stop when the battery reaches it's predefined level. Modern battery chargers (will come with some kind of over charging protection also. Even if you leave the charger on for 20 hrs, it will still cut off once the battery is fully charged and not continue to charge non-stop for 20hrs.

Initially for lithium-ion batteries(consumer electronics ones), i did not know there is a tiny strip of circuit board built into the battery unit until one of my colleague dismantled one and showed it to me. The circuit board looks something like this :

I later came across one of Maxim's battery management IC datasheet and browsed through it. It mentioned that "overcharging or overdischarging a Li+ cell can cause it to explode", thus i believe all lithium-ion battery will come with some kind of built-in over charging protection and there is no way charging longer hour will have any benefit. The charging protection circuit will eventually stop charging once the battery is fully charged. Below is a sentence extracted from Maxim Battery Management Application Notes :

Lithium-Ion Safety
Because overcharging or overdischarging a Li+ cell can cause it to explode and injure people, safety is a major concern when handling this type of storage cell. As a result, commercial Li+ battery packs contain a protection circuit, such as the DS2720 (Figure 7). The DS2720 provides all the electronic safety functions required for applications that involve rechargeable Li+ batteries: protection for the battery during charge, protection for the circuit against excess current flow, and maximizing battery life by limiting the level of cell depletion.

For the full application notes click here
Nickel-cadmium (NiCd), nickel-metal-hydride (NiMH), and lithium-ion (Li+) battery chemistries are also discussed in the application note.

For me, once the indicators says charging completed, i will just switch off the charger. There is no point in leave it running "idle" since it has completed it's task.

So, to answer your question of whether to charge your battery for 8 hrs, the answer really depends on how long your charger takes to inform you that charging is completed.

Hope this helps......

Spot one! :thumbsup: Ask those flashlight enthusiasts who own plenty of rechargeable Lithium-ion batteries. It is an established fact that Li+ can be dangerous if not properly handled. Over charging and over discharge can cause it to vent or explode. For that matter, some of these batteries come with a build-in Protection Circuit Board (PCB) that will cut off the charging / discharge once it reaches a certain voltage. Most charger will also cut off the charging once it reaches it desired voltage and it works both way. You get protection from the charger as well as the batteries' PCB. Once it is fully charged and the charging cuts off by the charger, leaving it on the charger for a few more hours is not going to increase the charge. On the other hand, it can be dangerous if the charger doesn't cut off when it reaches it desired voltage and the battery's PCB is faulty. The end result is an explosion. Call me kiasu or anything but I always ensure that the moment my charger indicates that my CR123 and/or 18650 batteries are fully charged, I will never attempt to leave it on the charger for another hour or more just to get more juice despite the charger having its own cut off circuit and the batteries are protected type (with PCB). You never know what can happen. Besides, I test my 18650 batteries, after a charge, I use a multimeter to ensure that it reaches 4.20v and nothing more.

 

[WuffRuff]

So regarding charging cycles, what if you keep your laptop constantly powered, how does it count the cycles? I think what it does is charge, stop, battery gets drained, it charge, battery full, stop, and this goes on right?

Also, I've ever had this encounter that I still can't figure out.
I was charging this rechargeable AA battery (think should be li-ion), using the original and correct battery charger.
It was in a mountain lodging (make mention cos not sure if altitude had effect).
Actually it wasn't charged that long too. Maybe it was a few hours (around 3 hrs +/-), and the battery started sparkling and fizzling. Sparks were flying and by the time we turned it off, some parts of some batteries were already fried - black.
And that battery was very new... think 2nd or 3rd time charging!
Any battery expert here has any idea what could be the cause?

After this incident, I always have this distrust when charging my batteries or devices, especially so if overseas!