This is not car batteries related but I need to learn some basics behind battery saga . It's advised to not fully charged your notebook battery. Because it shortens it's lifespan .
However, to pick the optimum life of your notebook battery ,you should drain the battery and fully charged every 1 or 3 months .
This is where I don't get the things , since fully charging the battery everyday is not a good habit, why on earth it would help extend it's life in 1-3 months ?

 

Cadillac, this is where understanding the design of the battery and how it functions comes into play. Your notebook most likely has a lithium based battery in it. These are known for developing a "memory" to them. What this means is that with use, some of the spots that would normally discharge to give you power, "learn" to not do that. So, in short, you may only get but say 60% of your battery that hasn't learned something. So, by doing intermittent charges, you are "confusing" the battery on how it should perform and the battery will not learn as much. Then, by doing a full charge, you are really mixing things up and taking a lot of the pieces that "learned" something and you toss them on their heads and they unlearn things. Hence why you get the more capacity and the longer life.

The same sort of thing can be done with your car battery, but in the reverse. Due to the style of battery in your car (lead acid), it will develop a moss (think of it as little fingers reaching for the next plate). If the moss can touch the other plate, it kills a cell and your battery suddenly has a large loss of capacity (hence why you can start your car one time and then shortly there after the battery is completely dead). To "kill the moss", you simply do a partial discharge of the battery (about a 10-20% discharge) using a discharge rate of about 10 amps (10 amps for about 1 hour seems to work nicely). This will leave enough charge in the battery to allow you to start the car without a jump, yet, deep enough that it will remove a lot of the mossing. You do this say 2 times a year (can get away with 1 time a year) and you can get more years out of your battery.

I learned about mossing with the battery on the submarine I used to live on. But, considering that it used the same sort of battery as was in my car (just on a much more massive scale), the information was useful in maximizing its life.

 

What a deep and informative post , thanks Thermo
Now, I get a better picture about batteries charge/discharge vs lifespan effects

 

Cadillac, the big thing to keep in mind is that batteries that are meant for "starting" a car (your typical battery, but by the industry is referred to as a starting battery) should only do that (for the most part). To drain them to near 0% life and then recharge them actually causes great harm to the battery and can result in a very short life. Hence why you will normally find that if you have a hard time starting a car and you are cranking and cranking on the battery, shortly there after you will be replacing the battery.

Now, on the other hand, you take a deep cycle battery (something meant to be discharged to 0% and then recharged over and over), if you maintain them at 100% charge for a long period of time, they will undergo mossing like you wouldn't believe and they will actually kill themselves off due to the cells shorting out. So, a deep cycle battery should be discharged deeply and then recharged atleast monthly (if not more often) to maintain its life. The same is true of a laptop battery. It is effectively a deep cycle battery. Too keep it at 100% causes a lot of harm.

 

If your laptop battery is NiCd (Nickel Cadmium) or NiMH (Nickel Metal Hydride) need to be exercised across the charge range (not overcharged , rather than not fully charged). Lithium Ion batteries dont need this sort of attention and do not develop memory issues.

If you want to understand battery issues and chemistry a bit better the following is a good site:

Lithium-based Batteries Information ? Battery University

 

Thanks again for your replies guys , much appreciated
I believe this topic should also help understand effective battery usage for forum members as well