this is my first question on this website, so please excuse me if I did not follow the guidelines correctly.

I have an Alienware 17 R1 (2014) and have been looking into rebuilding its laptop battery that has been dead for a while now. I have read up quite a bit into battery chemistries etc., but I would appreciate advice from the experts here regarding my little project.

I am a computer enthusiast, but rebuilding a battery pack is something I have never done before. My laptop battery uses a 4S 2P configuration of 18650 cells for a total of 14.8V and 5.6A. I want to replace these cells with higher capacity ones, but am unsure of what cells to buy (unprotected or protected), and if directly soldering onto these cells is really a good idea. What I am worried about the most, however, is if this modification will result in a battery that is unsafe and might result in my house burning down.

One last question that I feel is relevant to this topic. I was also thinking about replacing the optical drive bay of my laptop with more 18650 cells for more battery life, I read about another guy doing this in this forum: https://www.overclock.net/forum/158-laptops-netbooks/1528118-guide-tutorial-upgrading-your-laptop-s-battery-life-without-wasting-existing-battery-capacity.html. I was wondering if I can do the same safely. I know for a fact that the batteries will fit (took the measurements).

Please feel free to inform me of any equipment that you feel I should have when building the battery. I already have a list, but I am open to more advice and suggestions.

Thank you so much for your time and advice, I will select the best answer in a week.

  • 2
    \$\begingroup\$ Just by a new one. It's not worth the effort. \$\endgroup\$ – Tom Carpenter Jul 1 '18 at 18:18
  • \$\begingroup\$ 1) For my own battery, maybe I would consider going that route. But if someone has to ask, I'm not comfortable with taking the responsibility of giving them an answer. 2) If your laptop battery pack has lasted less than 4 years, either the original cells are very bad quality, or the battery management system is not treating them right. If it's the latter, then your new cells probably won't last long either. \$\endgroup\$ – Dampmaskin Jul 1 '18 at 18:48
  • \$\begingroup\$ Unless you are good at cold welding, matching impedance , selecting good sources to match them and fusing technology, it’s not trivial but watch YouTube videos with follow ups that demonstrate failures and successes with lessons learned. \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Jul 1 '18 at 19:02
  • \$\begingroup\$ You know why laptop batteries are expensive? Because good 18650 cells are expensive. If you would buy proper cells then the price difference compared to proper a 3rd party (OEM) laptop battery isn't going to be that large. Cheap cells are nearly always of crap quality and not worth buying. Used cells will be worn out and not worth buying either. In the end you get what you pay for. \$\endgroup\$ – Bimpelrekkie Jul 1 '18 at 19:20

As Tom Carpenter commented, "Just buy a new one. It's not worth the effort."

First, you need to get unprotected cells, because the local individual protection circuitry will interfere with balanced charger built into the "smart laptop battery".

Second, you will need a welder to connect new cells, reliable soldering would require either a low-temperature alloy, or careful temperature control, not to overheat cells. Unprotected cells need some care to handle, to avoid accidental shorts. You might need to deeply discharge the cells before handling-assembling them.

Third, and most important, you will need to match the cells that go to paraller (2P) connections to 1-2% in terms of internal impedance and capacity. Without matching the 2P sections will wear itself down rather quickly, in 50-100 cycles, and die. When the smart batteries are assembled by manufacturer, their factory has thousands of cells to select proper matches using special testers. You don't have this luxury.

"Just buy a new one. It's not worth the effort."

  • \$\begingroup\$ Thank you for your advice. I have bought a battery from laptopbatteryexpress.com as I heard they use high-quality cells in their battery packs. Guess I'll just have to make do with that. \$\endgroup\$ – user192581 Jul 8 '18 at 23:38