Batteries - Nimh / NiCad / Lithium Ion Charging Question?

I was told recently that one of these types of batteries came pre-charged and ready for use right out of the package, but I can't remember which one. I was also told that if you don't charge the other kinds first it will screw up the memory and the battery will only hold only the amount of charge that was in it when it was first put in the device. I have in front of me an NB-2L for my digital camera, and I wanted to know if it needs a charge or not! Thanks!

Sorry, I didn't mention in the original post that this is for THE FIRST CHARGE. Whoooops!

Since you don't know how long the battery may have been sitting on the shelf at the retailer or in inventory at the plant that made it you don't know the state of charge that battery has when you buy it. I have never read the instructions for any battery that didn't say to charge the battery before the first use. The instructions usually say to charge it for 10 to 12 hours. This finalizes the chemicals in the battery. I would wonder who told you the battery came fully charged. Even if it was a sales person in the store you bought it from doesn't mean he really knows what he's talking about.

You should use the battery until it dies, then charge it to completely full. You won't build up memory in the battery from draining it, only from charging it when it's half-full. This is true of NiCad, and less pf a problem with NiMH and lithium ion.

Always charge it first when it is new. All batteries.

However, the most critical one that must be "fully" charged when new is the NiCad. They ship NiCads with just a tiny charge because they will live longer stored at 1.00 volts per cell.

Lithiums last longer stored in a fridge at 40% discharged. This is only if you are a company selling them, or you are not going to use it for 6 months or a year.

The only one that has memory problems is the NiCad.

You are really never suppose to discharge any of them completely... only discharged down to 1.00 per cell. If it is a 6 volt battery, that means it has 4 cells inside. It is actually truely rated at 1.25 x 4 which is 5 volts. I'm talking about NiCads. However no one really has the equipment to shut off the discharge at 1.00 volts, so they generaly say to completely discharge it. You do this to remove the potential memory effects. The point is the cell manufacturer (in the USA, believe it or not, it is GE) that sells them to the battery company tells them never to discharge it below 1.00 volts per cell. The reason? If it is an old cell or a sick cell the voltage can "reverse" and destory the cell, and therefore the entire battery.

My experience has been if you fully discharge it and it kills the cells, it's probably good as it was going bad anyway. Internally to batteries that produce a lot of higher voltage than let's say 6 volts, it has individuals cells inside. For instance those little batteries that pack 6 volts for a door bell, are acutally 4 tiny cells connected together in series. Each one has a small fuse between them in the event one cell reverses. So it doesn't get hot and explode, the fuse just burns out and the battery is then dead.

The memory problem works like this for a NiCad. A nicad will hold its voltage for a long time and then the voltage will fall off quickly. This isn't how regular batteries work and they are more linear and just slowly loose the terminal voltage. So a single cell (possibly many wrapped in a container for higher voltage than 1.2 volts) nicad, will stay right at 1.25 volts until the very end. Then it will quickly drop off. (This is why it doesn't need to be 1.5 volts like standard batteries as they will eventually drain through the 1.25 volt stage at some point and still be considered a good battery.)

So within a few seconds the terminal voltage will go from 1.25 to 1.00 volts and below. The point is, that if you only use it a little bit... let's say from 1.25 to 1.24 volts, then recharge it, it will develop a memory where it will go from 1.25 to 1.15 volts. When it hits the 1.15 volts, it will quickly drop off to 1.00 volts. This is called the "memory effect" of nicads. You can "erase" the memory effect by completely discharging it and recharging it a few times.

The truth about nicads is that they can be charged and discharged many many times without hurting them. They actually die because they get dry inside and that typically is about 3 to 5 years.

Lithium is better for cold and hot environments. Plus it has good shelf life. That means if you fully charge it and put it on the shelf, then it will lose very little current over the next month.

Nimh has a terrible "shelf life." That means that if you put it on a shelf, it discharges at about 1% per day.... just sitting there. However, if you increase the room temperature to 100 degrees or freezing it can lose 10% energy per day. However, it's claim to fame is that it doesn't develop a memory.

BTW, I have a camera that uses the exact same battery that you have. I have both a Lithium battery for it and a Nimh. By far the Lithium is best.

Also understand that the term "shelf life" has two different meanings. One is how long it will live before it can never be used again and another one is how useful it is after sitting on a shelf for a number of months.