Lenovo resists 3s2p DIY pack connected to battery terminals

Regressive wrote 09/24/2022 at 21:06 -1 point

Hi, I have built a simple DIY 3s2p battery pack from 2170 cells with balancing and anti-overcharge/discharge.  I want to connect this pack directly to the battery connector of the Lenovo T540, replacing the Lenovo issued battery pack which is kaput.  This connector has 7 contacts, 4 being Gnd and Vcc.

There seems to be some handshaking going on the other 3 contacts.  The laptop does not recognize my DIY battery pack, and complains that "no battery is detected".

I would appreciate any help as to how to accomplish this.

I would not want to connect to the power input terminals, because that would mean my pack has to become a 5s2p -- too large and too heavy.

I can't replace the cells on the kaput Lenovo pack, as it has already self-immolated, and are 18650s.