Laptop Battery Technology


My laptop battery has finally taken the plunge and I'm looking online for a new one. However I'm getting lost in all of the specs of the batteries that are out there. I'm looking to gain a better understanding of what effect each spec has on the overall life of the battery (meaning length of hours that I can operate on battery power).

Some questions I have:

  • What do Watts equate to?
  • What do mAh (milli Amp hours) really mean?
  • Does voltage have an effect on the life of the battery? (I understand that laptops can support multiple voltage types reference)
  • Do 9 cell battery have a greater battery life than that of 6 cells. If so, by how much?

Give to me what I should look for in a battery that will affect the battery life the greatest. Some questions I have in this regard:

  • Are Watts or mAh are the greatest factors to look for, or if it's a combination of the two, or something else entirely different.
  • How much difference is there between two values of the factors (i.e. 4800 mAh vs. 7200 mAh)

It doesn't have to be these exact numbers and in fact I don't want specifics but rather a general rule of thumb

I am NOT looking for "This is the best battery to buy" or "This is the best company to buy from". I am NOT looking for just links to websites that I have to sift through. If you post a link, please summarize what it says. I AM looking for a greater understanding of the technology behind it.

Best Answer

As far as battery technology for a laptop, what you've got is what you're stuck with for the most part as the charging electronics to different battery technologies are internal to the laptop itself.

That said, you've asked good questions about the terms used to identify batteries - mAh (yes, milliamp hours) and W (watts).

Watts are a standard way to measure power output of any electrical device. The best measure for a battery would be in Watt-hours, measuring actual energy capacity of the battery. (Watts = Volts * Amps)

A second-best measure would be the mAh measure which would indicate how much current the battery can supply over time at the specified voltage. (I used this figure frequently when selecting AA rechargeable batteries.)

I've not heard about voltage variations between batteries. Essentially the most efficient battery will be the one with the voltage that best matches what the computer's internal electronics were designed around. Any excess will be frequently lost as heat as the internal electronics convert the voltage to the proper level (which is probably not a figure specified by the manufacturer - they're more likely to supply a figure denoting the range of voltages the laptop will accept).

Bottom line for most batteries is that shelf-life is still a factor, so look for a reputable dealer with an indication of when the battery was manufactured since an older better specified battery may not have the capacity of a new battery with poorer specifications.