What state information are you after? State of charge, voltage, capacity, internal resistance, etc?
Do you want control over the LVC/HVC (per cell, etc)? Does overcurrent matter? Temperature?
Most of the "smart" BMS can give you cell voltage (assuming you're using single large-format cells to make the seriesed "groups" from, rather than multiple paralleled cells), but I'm not sure which (if any) can do more than that at the cell level.
Some of the smart ones have various serial outputs (CANbus, RS232, RS485, etc) or Bluetooth to an app on your phone/etc, some of the serial ones also have displays to receive the data (otherwise you have to figure out what's being sent and decode it yourself; I wouldn't bet on much documentation for most of them).
Presumably if the vehicle is a Volvo, it's big enough to be drawing hundreds or thousands of amps, so you'll probably need a contactor-based BMS (rather than one that uses FETs to pass the system current).
I don't recall how many series cells they handle directly, but JBD makes a few contactor-based types. Since they are not directly controlling the whole pack output, then if you can't find one that does enough cells, you can use two or more wired up so each is powered by and monitoring a section of the seriesed cells. Optoisolate all comm / etc lines, and use their control outputs as inputs to a logic device (discrete parts or an MCU (arduino, etc)) so that if *any* of them tries to turn the output (contactor) off, the contactor turns off. Then the contactor will be on as long as nothing is trying to turn it off. You can add an ignition/keyswitch input from your dashboard, too.
A better way is to not allow it to directly operate the contactor, but instead to notify the controller there's a batery problem, and let the controller do limiting or shutdown based on what's happening. (or use the MCU for that). That way nothing but you can actually disconnect the battery (via the main keyswitch), which can prevent a number of unforeseen problem situations.
There's a very few modular BMS like Orion, I think Ennoid, and I forgot the name of the other one that had a project thread here on ES before it went commercial; might be by AgniusM?
