My laptop is 7 years old (bought in november 2012) and I've had 1st battery ever since. Whenever I plugged it into power plug, I always removed battery. Even though, after 7 years of use the battery lasts ~1h, while laptop works perfectly. I decided to change 18650 batteries in the battery pack, but here's the catch: Original battery's specifications are: 10.8V 4700mAh 50Wh.

I would like to remove all 18650 batteries and replace them with new, better ones, such as Samsung INR18650-35E 3450mAh. Here's the thing: Could there be a problem with replacing old (original 18650) batteries with new 18650 batteries, which has higher energy charge than the original one had? I am talking about laptop power supply, battery charger unit and anything else, perhaps?

  • \$\begingroup\$ Will they fit? I expect you need 6 in 3S2P \$\endgroup\$ – Tony Stewart EE75 Nov 10 '19 at 1:49
  • \$\begingroup\$ they will fit, it's standard size for 18650 \$\endgroup\$ – Jakey Nov 10 '19 at 22:33
  • \$\begingroup\$ is it 3S2P as I suspected? \$\endgroup\$ – Tony Stewart EE75 Nov 10 '19 at 22:35
  • \$\begingroup\$ I didn't open it, but I assume very same aswell - due to information given on the battery's sticker. \$\endgroup\$ – Jakey Nov 11 '19 at 13:36
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    \$\begingroup\$ You may open it before safe disposal to learn how they are joined. Be sure your batteries are balanced <0.5% for best long term performance in capacity and ESR. and voltage prior to shunt connection \$\endgroup\$ – Tony Stewart EE75 Nov 11 '19 at 14:58

The higher capacity should not be a problem.
Problem usually is the control/protection circuit inside the battery pack. It usually detects when you disconnect old battery cells, and marks that battery pack as faulty (doesn't matter that you put good batteries in). The battery pack is no more usable after that.
It happened to me.


Foul the bms. First connect the new cells to the bms before you take out the old ones. Once the new ones are connected you can remove the old ones. As long there is power to the bms via a cell, there will be no problem.

Basically you enlarge your total capacity on a "live" battery bank, by paralleling the cells, then when all is installed you cut the wires to the old cells.


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