I have not taken the Z1 apart. Perhaps someone on the forum has more information and they will be able to answer your question.
The V has a battery in it that has a 1360mAh rating. I imagine that the Z1 has a larger battery.
I replaced with V battery with a 1500mAh LI90B/92B and it is still working after almost a year.
I do not recommend taking apart the Z1 unless it is completely dead and you have no other option.
You can attach an external battery to your tripod and power the Z1 for the duration of your shoot.
The Z1 has both sleep and power off modes. Before the shoot, power it off. During the shoot, put it to sleep when possible and charge it from a portable battery pack and USB C cable when you are not shooting.