Controller/memory/discrete components are all pennies and there is no earthly reason why 48 temp and 25 voltage wires should present a problem to the control/monitoring/charging unit.
At least for the temp sensors there is no need for more than 3-6 wires (depending on any redundancy desire) since there are plenty of serial bus (more than one flavor) temp sensors available.
Some of these also have voltage monitor inputs but then things get a bit complex due to common mode issues etc.
Accuracy is not a major factor, +- 1 degree C would suffice, rates are probably as interesting as absolute.