General Battery Life Questions (RC512)

Morning everyone. My work laptop is a Dell E6400 so I could care less about good battery techniques. After about 1.5 years the 4h45m battery is down to about 4 hours. I'd say that is 35% unplugged and 65% plugged.

I just got a RC512 (Core i7) for my b-day, yay! Sucks that it doesn't have a backlit keyboard like my dell but I will manage. Anyways, I have some battery questions since I care about this more than my work laptop.

Battery Life Extension Bios Option:
There is an option, which is off by default, to only charge the battery to 80% to lengthen the life of the battery. How do you experts measure something like this?
- For example if I use the battery at 100% and get 4 hours, one year from now lets assume it has degraded to 80%. During that time I was able to get 4 hours for while.
- Now if I had used the 80% option, I would have only gotten around 3 hours of time and after a year be at the same place.
Can someone explain the big benefit of this?

Leave plugged in all the time or not?
I read lots of myths about charging all the time "shortens" the battery life. Is that really true and how is that metric measured? If 1 year of charging causes the battery to lose an additional 3%, that is not worth worrying about.
I have a gadget that shows the charge and discharge rate and when I have it plugged in, and the laptop is full, the charge rate is 0W, meaning that it doesn't charge for nothing when it's full.

Ultimately, if I can use the laptop with reckless abandon and after a year I may need to buy a new $35 battery because mine is at 80%, that seems acceptable.

 

Second question first: All modern computer BIOSes stop charging the battery when it is full. Also, most don't start recharging until the charge level has dropped several percent, so top-up charges when left on mains power will be relatively infrequent. You can do a few quick tests to check what the RC512 does.

Regarding the battery life extension, I share your scepticism about the effectiveness. What is the battery power rating? This feature may make more sense when trying to squeeze more power to top up the high capacity batteries (ie 66Whr 6 cell batteries) because that will be when they are most likely to degrade. Perhaps, by only using the maximum capacity when it is needed, there is less overall wear. It's possible that the overall wear will be less if the recharge is normally limited to 80%. However, if you need to use most of the capacity on a regular basis then regular depletion of the battery down to empty is probably just as damaging as the full top-ups.

John

 

turn battery life extender off to increase t0 100% i liove my rc512

 

The 80% cut off charge is only when it's plugged in to prevent overcharging. This should prevent the battery from losing it's charge capacity in the long run but then again the battery is suppose to know when to stop charging itself. The question is that if the battery is fully charged at 80% then battery run time will be 20% less than when it's 100% charged. It's a weird logic.

 

My understanding is that 80% charged means 80%. The batteries last longer if not used at either end of their capacity range. So, if you know that you don't need a fully charged battery then the 80% cut-off should improve its longevity. ie Battery Life Extender is intended to improve the time before final death, not the run time (which many people call the the battery life).

John