Source: Tom's Guide US | Keywords: notebook, extended, battery | Themes: Laptops and Notebooks
4. Battery Specifications
You may have two or even three battery choices for your particular notebook model. Be prepared for three common battery terms "number of cells," "amp hours," and "watt hours." Each of these determines your battery’s capacity and understanding them will help take the guesswork out of choosing a battery.
For example, when I bought my HP dv4t, I had the choice of three options when configuring my battery:
- Standard six-cell battery rated at 2.2 amp hours and 47 watt hours;
- High-capacity six-cell battery rated at 2.55 amp hours and 55 watt hours;
- 12-cell extended battery rated at 2.2 amp hours and 94 watt hours.
If you look closely, you will notice that even though the 12-cell is only rated at 2.2 amp hours, it still has higher watt hours than the six-cell rated at 2.55 amp hours. That’s because it has more cells. Basic math suggests that the number of cells, along with the amp hours, will determine your watt hours. The higher the number of cells and/or amp hours, the higher the number of watt hours. It’s always best to look at watt hours if you cannot make the determination between cells and amp hours or if the battery description is not clear.
Some notebooks may not include a configuration option, leaving you with just the option to buy an extra standard battery in addition to the one that comes with your laptop. Others notebooks may have options like a three-, six- or nine-cell from which to choose. Check your owner’s manual or go online to the manufacturer’s Website to see what batteries your particular notebook can support, and look up the specs to determine your battery’s capacity.
Finally, while having more cells does translate into longer battery times, it may not necessarily give you the most efficient solution. When looking at HP’s smaller dv3t notebook, the company offers a nine-cell extended battery rated at 2.55 amp hours and 83 watt hours. This is actually very close in performance to the 12-cell, but in a smaller and lighter configuration. It’s something to keep in mind when comparing models.
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There aren't any options in the bios so is there software to undervolt my notebook's CPU?
They rate Amp-hours per cell. I.e. 2.2amp hours is only for one cell of a multi-cell battery? Confusing.
w4ffles: I use RMClock myself (there should be a free version online). It lets you set profiles so you can specify the maximum speed and voltage of your CPU (and various other levels depending on CPu usage). I use it to underclock and undervolt my desktop when not in use, but to crank the CPU up to max when doing heavy loads (which the application detects automatically and adjusts on the fly).
It can take a learning curve to use, but even the free version is very powerful.
Just something to point out, DDR3 is a power saving component in notebooks right now since it runs at a lower Voltage than DDR2. The difference isn't particularly significant, but DDR3 will give you maybe 5-10% more runtime.
Most people think of DDR3 as a perfomance increase, but with the limited frequencies of current soDIMMs, DDR3 for laptops is only on par with current DDR2 notebook RAM, if that.
My Compaq V5000 is still going strong after 5 years. I chose to go with Sempron and the matte screen (I planned to work outside and the glossy was brighter by default). Also got the 12 cell. I play Starcraft, Diablo 2 so the ati 200M worked perfectly, and then work related stuff (lasts about 6 hours watching downloaded media).
Great article, these were the things I considered when choosing components for my laptop, as I never knew when I would be close to an outlet.
andetghddn -
P.S. The v5000 laptop also cost about $450 direct from hp.
They rate Amp-hours per cell. I.e. 2.2amp hours is only for one cell of a multi-cell battery? Confusing.w4ffles: I use RMClock myself (there should be a free version online). It lets you set profiles so you can specify the maximum speed and voltage of your CPU (and various other levels depending on CPu usage). I use it to underclock and undervolt my desktop when not in use, but to crank the CPU up to max when doing heavy loads (which the application detects automatically and adjusts on the fly).It can take a learning curve to use, but even the free version is very powerful.
RMClock is the defacto software in use on notebooks at the moment, and what I would recommend. While I don't want to get into a full-blown guide here, it is also important to stress the CPU while testing your voltages before you really play with RMClock. It does take some learning, but anyone with the skills can do it.
Cool - now I can get a 30% off coupon at HP. Nice article!
I always enjoy having a laptop battery that doesn't start a fire.
I have a busniess notebook for work and aside from the programs I use everyday, don't know that much about computers. The biggest thing for me with buying an extended battery was the price. HP wanted a boat load for it, which is really a rip off. I checked different site for about 2 1/2 days and ended up getting one from NoteBatt.com for like half or something close to it. Couple of other sites were the same way. It's just nuts to think that other companies are selling pretty much the same battery for much less. Oh, and it has been completely bug free since I got it, something HP told me would not happen.
Even with 30% off coupon I think HP batteries are very expensive. I also was scared about fire when I started looking for a new battery for my HP and I found a very high quality batteries at www.newpcbattery.com. I chose that site because battery manufacturer located in USA, not in China.