The option of replacing the cells in a genuine battery may be worth considering as an alternative to modifying the EC firmware, the advantage being is that you can choose your own high quality Li-Ion cells versus whatever you might happen to get in a replacement battery.
I suppose the whole "safety culture" around lithium cells in laptops has yet to change, but high-quality 18650 cells have been available on the open market for several years now, with all the accompanying products that use them (torches, vapes, power banks, etc.) The general public handling bare lion cells has increased significantly, whereas the amount of incidents related to cells catching fire etc. doesn't seem to have increased correspondingly. The majority seem to be from lipo "pouch cells" which are definitely far more fragile and less resistant to abuse. (They're also higher density = more energy to cause excitement when things go wrong, this is the type that's been causing the hoverboard fires.) 18650s are more robust and it's hard to cause a fire unless they're seriously abused (e.g. severe overcharge or physical damage.)
Given that you can buy empty power banks and add your own cells like this...
...it's odd that I haven't found similar battery cases for laptops. (Or maybe they do exist and I'm just using the wrong keywords. If they do, please say so; that seems like a great product to have.)
The general public handling bare lion cells has increased significantly, whereas the amount of incidents related to cells catching fire etc. doesn't seem to have increased correspondingly.
This may in part be due to certification and testing methodologies [0] for battery packs. The issue is that not all cells/battery packs go through this testing, so unless the batteries have been appropriately certified, there are restrictions on the handling and transportation of these batteries (for example non UN 38.3-rated cells are not allowed on planes [1]).
CE manufacturers test and certify the batteries in their products ([2], [3], [4] for example) which is why Amazon can ship them by air and passengers can carry them on planes. The issue is that 3rd party batteries may be uncertified and possibly unsafe. Lenovo doesn't want to take responsibility for an uncertified battery in one of their laptops downing an airliner [5] so they disallow the use of batteries they haven't certified. I doubt this is a nefarious scheme and more about potential liability.
(at my company we use lithium-ion battery packs for our field equipment and had to become very familiar with these issues when IATA promulgated their lithium/lithium-ion battery pack shipping rules a couple of years ago.
I suppose the whole "safety culture" around lithium cells in laptops has yet to change, but high-quality 18650 cells have been available on the open market for several years now, with all the accompanying products that use them (torches, vapes, power banks, etc.) The general public handling bare lion cells has increased significantly, whereas the amount of incidents related to cells catching fire etc. doesn't seem to have increased correspondingly. The majority seem to be from lipo "pouch cells" which are definitely far more fragile and less resistant to abuse. (They're also higher density = more energy to cause excitement when things go wrong, this is the type that's been causing the hoverboard fires.) 18650s are more robust and it's hard to cause a fire unless they're seriously abused (e.g. severe overcharge or physical damage.)
Given that you can buy empty power banks and add your own cells like this...
http://www.aliexpress.com/item/1Pc-6-X-18650-Battery-Case-Us...
...it's odd that I haven't found similar battery cases for laptops. (Or maybe they do exist and I'm just using the wrong keywords. If they do, please say so; that seems like a great product to have.)