LI ION BATTERY PROTECTION

It looks like the battery has built in protection at 2.3V. Do you need your own at 2.7V as well?

If so there are special ICs for theis job. For example look at:

Are you protecting the battery or your circuit ??

don

Hi,

I am trying to protect the battery.

John

How I can calulate the charge and discharge time of this battery.

Thanks

John

The battery has built in protection

Basic question.

The capacity is 120mAh. At 24mA discharge it will run for 5 hours.

The charge time is shown in the graph on the data sheet. About 2.25 hours at 60mA charge current.

There are 2 layers of protection for lithium rechargeable batteries: (1) a small IC with 2 external FET's which is on a small PCB built into the battery on its "protection board". Most people are not aware it is there until they cut a battery open. This prevents you doing a deep discharge (4.3V), at which point the battery chemistry changes and becomes dangerous.

Google "lithium ion protection ic" for more information on these.

However I think you are asking for an IC which will help you build a charger. (2) These Li-ion charge IC's are made by many companies. I would suggest Linear Technology

because although they will be expensive, they have good notes, and they will still be making the same IC in 5 years' time. They also make protection IC's.

You can tell the charge / discharge state of the battery either by voltage or "charge counting". I have never used a charge counting IC because they are poor at calculating remaining charge when the current drain is very low (we were aiming for batter life of months). Voltage has its own problem, it varies with temperature as well as charge, but maybe your application is a nice constant temperature like something used indoors.

If you display charge level on an LCD or similar, use just 3 bars, not 5 or a percentage. That is because users get upset if you show too much accuracy and it takes 1 hour to discharge through 1 bar, 2 hours to discharge through another. Then one day they pick it up and it is a cold day and the number of bars is "wrong". It is best to be as vague as possible. All users want is a rough idea of "is this thing fully charged or not".

I think I already advised against using Ultralife. And someone else pointed out this battery is obsolete?

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Nemo

Of course Linear Tech was the supplier in those Apple notebook charger fiasco. Though in general, Linear Technology is a great company, so I suspect Apple so-called engineering may have been the source of the problem. People were really tight lipped about the recall.

There was a time you couldn't buy a lithium ion cell without the manufacturers protection chip. They wouldn't trust your protection.

Try this.

the story I heard on one of the fiascos was the product was being produced in china. Someone got the registration wrong in production, so all the protection chips were put in rotated 90 degrees. Since that didn't work, they were just jumpered around, and thousands were produced...

Charlie

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This gets confusing since Apple has had a few battery issues. However, my recollection is at the time of the fiasco I am thinking of, the batteries were still in packs, not mounted in the macbook like the current generation product. It was a charger issue, not an issue with the packs. However, that could have been the cause of one of the fiascos.

Now a good question is does Apple use SMB. I can't see a pack with messed up protector chips passing an decent SMB coding.

The current fiasco with Apple is crappy DVD drives in the desktop boxes.

Actually, the story I heard was about cel phones...

Charlie