Laptop battery life increaser - would this work?

[stevemilwa]

Hello, an idea struck me the other day when i was using my laptop.
Ive noticed that with many people, if the battery is left in whilst the power plug is in (which is how allot of people tend to leave their laptops) the battery will reach 100% and then the amount of power recharge cycles will increase from that point onwards. so for instance, it will use the battery down to 95% and then recharge again. A li-ion battery only has a certain amount of recharge cycles.
This always reduces maximum battery life. If it is constantly left in when the user is at home, the battery life will decrease and ever make the battery un unusable.

If i developed a add on in which the power plug REPLACEs into before the laptop, the this device can communicate its status of either charging or not, either wirelessly or wired to a device that cuts off power to the battery.
In a common laptop battery there are about 9 slots in which 9 copper plugs go onto.
Is there a material which could be placed over the copper plugs, which could switch conductivity to allow current to pass through and to not allow current to pass through. The material could be switched between conductive and non-conductive electrically, much like a transistor.

Is a material like this available?
What do you think of the general concept? 

[Hero999]

Hello, an idea struck me the other day when i was using my laptop.
Ive noticed that with many people, if the battery is left in whilst the power plug is in (which is how allot of people tend to leave their laptops) the battery will reach 100% and then the amount of power recharge cycles will increase from that point onwards. so for instance, it will use the battery down to 95% and then recharge again. A li-ion battery only has a certain amount of recharge cycles.
This always reduces maximum battery life. If it is constantly left in when the user is at home, the battery life will decrease and ever make the battery un unusable.

I've heard of this sort of thing before but never seen any real evidence.

It's certainly true that laptop batteries have a limited number of charge and discharge cycles but the rating is in full cycles, not partial cycles. Discharging a battery to 95% capacity then recharging to 100% does not cause as much wear as discharging it to 5% and recharging it to 100%. Li-on batteries also don't like being fully discharged, in fact most batteries don't and will wear more if fully discharged, then completely recharged many times. If your proposed device ensures that the battery is completely discharge before it's recharged, it would actually shorten the life of the batteries not lengthen it.

The grain of truth in what you've said probably comes from the fact that, it's bad to store Lion batteries in a fully charged state, the recommended  storage charge is 40%. The laptop or battery will probably also have a digital fuel gauge which might only be calibrated when the battery is completely discharged and recharged. This might be important if the laptop shuts down when the battery is low; if it's not calibrated then it might shut down when there's plenty of charge left.

If you want maximum life then don't discharge past 30% or leave your laptop battery, for long periods, >40% charged. A more sensible option is to remove the battery from the laptop (again 40% charged if possible) when you're running it off mains power. Heat is the biggest battery killer so store the battery in a cool and dry place.
http://www.batteryuniversity.com/parttwo-34.htm

[stevemilwa]

oh ok, maybe theres more to what my friends have told me. According to them, their battery died because they left it in all the time, but theres more to it proberly.
maybe ill look into making a piece of software or something.
Just had one of thoes ureka moments whilst watching dragons den.