Trickle or disconnect charger for laptop?


I'm sure someone in the industry has beaten me to the punch on this idea, but not being very knowledgeable I can't find many references outside the normal marketing hype about buy my intelligent charger for $19.95 and whatever.

So, the other day I found myself wondering: which would be better for a laptop battery, a charger that goes up to a certain point and then completely disconnects, or one that gets to that point and trickles from there on?

The question stems from the fact that my laptop probably spends more than 90% of its on-hours docked and trickling. I imagine after 2 or 3 years of trickling like that, it probably wears down the battery. And you paid $40 for something that wore out without you even using it.

But then I thought, what if I had a software routine running on the laptop that monitors charge levels, and when the battery gets to say 90%, it sends a signal to an arduino that triggers a relay and cuts off the power at the outlet? So the laptop is actually cycling the battery and not just running off AC and forcing a trickle charge into your battery all the time.

I can imagine some drawbacks you'd have to correct in the OS, for example telling it not to cut your performance or screen brightness when it goes on battery. And you might find that one day you pick up your laptop to head out the door and it's only at 50% charge, though that could be handled using overrides or charge schedules.

But before I get too ahead of myself, would something like that actually improve or degrade battery life on the laptop?

What does this have to do with arduino? I think your in the wrong forum.

I don't use laptops, but I believe that the best course of action is to disconnect the battery when you have the chance to use mains and get power directly from the charger.

I know that constantly leaving laptops on the charger is bad for long term battery life, so it would probably be best to have one that disconnects after reaching full charge. My laptop has a "long term AC power" option that cycles the battery from 50% to 100%. When it reaches 100%, it makes the laptop run off battery power till it hits 50%, even if plugged in.

My wife's new Dell has that option to let battery discharge from 100% to 50% before it charges up again. Leaving a fully charged battery out of the laptop wouldn't be good. The battery discharges slowly and never gets charged up to 100%. I think most desk-top laptops have the same issue of battery wear-out without this option.

If you can find an old 50w PS and your laptop needs 65w it will do exactly what we want it to in Windows 7: Not charge. When you go traveling just bring the 65w. Simple!