A new battery in Dell laptops (12-04) as stated on Dells website will hold a charge for 4 hours. On older laptops of 3-4 years ago they will typically last 2-3 hours. Most new laptop batteries have a one year warranty, although some of the lower end laptops are now coming with 90 day warranties.

Since, more features keep being added to laptops they keep needing more power to run for the same amount of time. So, newer laptop lithium-ion batteries don't hold a charge more than the 3-4 hours they used to 3 to 4 years ago. Battery development is not keep pace with laptop enhancement.

If you need a really long lasting battery you will not find internal batteries that last more than 2-4 hours. So, you would have to consider an external battery or buy multiple batteries. Some laptop allow you to remove the CD or FD or have extra bays that will hold a battery.

I am not recommending any of these companies, as I don't have direct experience with them, so you need to call them and talked to their sales people and make your own determination. Any feedback that you can provide for others that view this blog entry are appreciated.

The manuacturers of external batteries that last five to eight or more hours are:

Electrovaya PowerPad battery products are rather expensively priced from $249 to $449 (special deal $424). Amazingly they only include a six month warranty! "The most expensive PowerPad 160 claims … - Upto 4 to 6 times more power - Highest energy-density rechargable battery in the commercial market". I found that a brand new Dell Lithium battery in new Dell laptops lasts 4 hours. They do not state anywhere I could find the actual time it will hold a charge, but I personally would be surprised if they last 16 to 24 hours? http://www.electrovaya.com/

The PowerPlant battery costs $99 and they don't state the warranty, nor how long the battery will hold a charge (5-10 hours), other than while flying coast to coast. http://www.pwrplant.com/notebook.html

Valence makes a five hour battery for $149 and has a one year warranty.
http://www.valence.com/ncharge2.asp

Check out the Google Answers post about universal laptop batteries:

http://answers.google.com/answers/threadview?id=186834

Within a couple years you can expect much longer lasting batteries with new laptops. Intel is working Zinc Matrix Power (ZMP) to develop rechargeable batteries based on Zinc Oxide, in the hopes of pushing the envelope on battery technology currently dominated by Lithium-Ion. They indicated that it would double the time a battery will hold a charge from 4 to 8 hours and are expecting this technology to be viable in 2006. http://www.infosyncworld.com/news/n/5016.html. Intel's Anand Chandrasekher, Intel's general manager of the Mobile Platforms Group has indicated that lithium polymer and zinc matrix are battery chemistries that might improve battery capacity. Fuel cell batteries will eventually be found in laptop computers. Toshiba claims they will eventually have a methanol fuel cell battery in a laptop.

Six months ago I did an extensive seach on the web to see who provided the best deals on laptop batteries. I recently updated the search and checked back to see the various vendors (100+) current prices. I only looked at one model IBM laptop (600 Series) to get an idea of what the prices might be.

The best deals seem to be from www.intelligentbatteries.com. Their price adavantage might be partially because of the difference between the US dollar and the Canadian dollar and partially because they designer, manufacturer and distributor of battery packs. The IBM 600 lithium battery here is priced at $62.00.

Other companies that seem to have decent prices are: www.priorityelectronics.com, www.meritline.com www.abatterypack.com, www.voltdepot.com and www.unisitebatteries.com.

Anyone that happens to do business with any of the above companies or find other companies with decent service and competitive battery prices should add a comment.