SE Thought

Friday September 01, 2006

Notes: extending battery life in notebook This is more of a notes to myself.
I bought Samsung Q35 notebook. Looking at the manual and FAQ, Samsung said:

• If you charge/discharge the battery repeatedly for only a short time, the battery use time may be reduced by the difference between the actual battery charge and the remaining charge display. Ok, so I must try to fully discharge everytime...
  
• Some third party vendors offer solutions that fully discharge a battery prior to full charging and Samsung recommend such solutions where the battery usage pattern does not allow for a full discharge / charge cycle to carried out. But Samsung does not state which vendors or products it recommends, and I don't know any (I don't need it, as Samsung Q35 has the feature).
  
• After 12 months or 300 charge / discharge cycles, whichever is sooner, Samsung recommends you replace the battery. This is not good. So if you keep the notebook for 3 years, you are supposed to buy battery on month 13 and 25. 3 batteries for 3 years.
• You should not buy the spare the battery too soon. Samsung batteries are warranted for just 15 months from the date of manufacture. not date of purchase. This reminds me of printer catridge.
• The first battery has 1 year warranty. But the second onwards only carry 3 months. It does not explain the reason behind this logic. "Battery's replaced under warranty within the first 12 months will carry the balance of warranty on the original battery, or a period of 3 months, whichever is greater. " Example: Original Battery replaced in month 11 will be warranted until month 14. Battery replaced in month 9 will be warranted until month 12, not until month 21)
• Even if you have 3 year warranty, battery warranty is not included. They follow the above rules.
  
• The notebook provides a Battery Calibration function in the Boot menu. The battery is discharged forcibly. This operation requires 3~5 hours depending on the battery capacity and the remaining battery charge. Interesting. If it's going to take 5 hours to discharge, I might as well let the it run idle until it dies (e.g. stay in BIOS after battery reach very low, don't boot OS so no 'hard' shutdown effect on OS).
  
• Turn off unnecessary device. I know this. But then it lists 1394 as device to be turned off. I wonder why, especially if I don't have firewire device connected to this port.
• Decreasing the LCD brightness by one level extends the battery use time by 3~5% (10~20 minutes). This is interesting. Just 1 bar in the brightness settings give 3-5% of battery life. BTW, if 3% is 10 min this means 3.3 min for 1%, if 5% is 20 minutes this means 4 min for 1%. This means the delta (2%) is beteen 6.6 min and 8 min can't be 10 minutes. I hope Samsung doc writer would be more attentive next time. 3.3 min for 1% gives 330 minutes, or 5:30 hours, which is pretty good.
  
• Published battery life is measured using full power management features. After 3 months of normal operation the battery's performance will start to degrade slightly, but even after 300 charge and discharge cycles the battery should still perform to 60% of its original life expectancy.