auto charging

leaving your laptop plugged in is bad for the battery life, so is there a software program that lets you set the charger and automatically turns off the charging when your battery is full and starts it when the battery reaches a designated level?

 

You are mis-informed that leaving your laptop plugged in is bad for battery life.

People around here leave their laptop plugged in all the time and have years of life in their batteries. I am an example of that, my G1 in my sig is a 3 months away from being 4 years old and I still have around 80% of original capacity. Others have bad luck with their batteries, but its not from leaving it plugged in, more likely lower quality or bad cells to begin with.

The battery charging circuits in the laptop will shutoff charging when the battery reaches full charge. Beyond that point the charger is running your laptop off the charger power, not the battery.

 

Whether or not running constant trickle charge into a li-chemistry battery is 'bad' depends on the quality of the charging circuit in the laptop and the management circuit in the battery assembly as well as the environment the battery lives in.

I don't think that anyone has ever done an evaluation of this when reviewing or rating laptops.

Tossing out a good or bad statement when talking about laptop batteries is pretty damned silly given the number of variables involved.

 

so I guess when someone comes in here asking battery questions we should just ignore them huh.

I have looked at several Li-ion battery designs, including the one in my laptop and I didn't see any that trickle charge upon charge completion. In fact trickle charge is not recommended in any info I have seen as part of charge profiles for Li-ion batteries

I know that trickle charge is common in NiMH batteries as I have much more experience in designing charging circuits with that chemistry.

 

answer the questions, have a discussion, but don't push all-in-one 'solutions' where none exist.

As for trickle charge, it's always there on a li-chemistry battery setup. The control circuit in the battery assembly decides whether or not to use it (or to call for a full power charge) and run it into the battery.

 

To the OP, I am not aware of any software that allows this kind of control, if anyone know of any please post so we all can look at it. Personally I would like to see some software that allows this.

I think the all in one solution of leaving your laptop plugged in is not bad advice. Now where in the laptop manuals have I read any cautions that stipulate this as being harmful? I can’t imagine any manufacture would knowingly or intentionally design a system where this would be harmful. For all intents and purposes leaving a laptop plugged is not going to hurt the battery in a way that is measurable if everything in the laptop and battery are working correctly. Please offer your advice in this regard, what would you recommend the OP do?

From looking closer at some controllers inside the battery, and the chargers themselves, (through net searches) the only time I see trickle charging is as a preconditioning to get the battery voltage up to a safe level before kicking in the high current standard charging. The only time a battery would need this is from letting a battery sit long enough in a low state of charge, that the self discharge lowered the voltage to this level. The safety circuits would notify the CPU thorough the smb bus that the battery is getting low and to shut down the computer, so that is not where this discharge condition would occur from. And again I do not see the use of trickle at the end of charge cycles. If you have info saying otherwise please share.

Because of the continuing questions about Laptop batteries, and since I have a good working relationship with a professional distributor of LI-Ion batteries I am going to ask them to provide me with as much information as possible about said batteries.

 

How on earth would software be able to stop the charging?

 

I'm fine with questions and answering ones that require some thought. But when a query is as misinformed and lazy as the one above, I tend to type out a snarky response and close the window without sending it to avoid making waves, unless someone happens to defends such a practice. If he'd bother to google it or search the forums, there would be some decent explanations already out there. I can recall at least 5 threads in the last two or three weeks about limiting battery charge to 90%, optimal battery charge strategy, hacking a battery to charge via direct power input, whether to remove the battery, etc.

Lenovo Power Manager does it, as well as some other laptop manufacturers' utilities. However, I believe there's probably a hardware component to this functionality.

 

There is the concern that leaving a battery in the laptop battery bay unused will result in long-term degradation of the cells, but this concern mainly stems from the heat produced by the internal laptop components. The solution is to store your battery in a cool place when not in use, or better yet, to simply use your laptop (battery included) in a cool place.

 

I'm finding the responses here a bit wierd. But, to answer the OP question:

Every single laptop with a Li-Ion battery in it already does this. The battery is charged to 100% and the charging circuit turns off. The charger doesn't turn on again until the battery charge drops to some predetermined point. On all except one laptop I have checked (three ASUS, one HP, one Toshiba, a Thinkpad T40, several old Dell C-series) this point is 95%. The exception is my Samsung R780 which is 96%. The charge dropping is due to either batter use (you unplugged the laptop) or self-discharge in the battery.

I probably should add that I don't know if the laptop turns the charging circuit off, or whether the battery does it. The former would be better as no power is being used. But, I suspect it is the latter.

Li-Ion batteries DO NOT get trickle charged once they reach full capacity. It will damage them. Plus, if they go past a certain voltage, again they will be damaged. Same as if the voltage drops to low. In both case, the protection circuit in the battery will cut in and may prevent the battery from being used or recharged.

There are some laptops that include an application to set the maximum charge level. The Samsung R780 has this and I believe some Sony's do. For the Samsung, it I believe it changes a BIOS setting and the laptop has to be rebooted before the setting takes affect. I assume that any other laptop that has this function also works in a similar way as the OS is not involved in battery charging at all. It all works the same whether the laptop is running or not.

 

If you leave your battery in and your laptop runs hot degradation can be caused to the batterys lifetime. HP recommends removing the battery and storing it at 30-50% charge if you are planning on keeping the laptop stationary for over 2 weeks.

 

Apart from the time frame, that is the standard storage suggestion for Li-Ion batteries. The Notebook Battery Guide is a good place to start reading on how to look after your battery.