thanks for all the info, Andy!
> The 'display board' (the small board with the pair of DB9 connectors) has both TTL level signals (for the warning buzzer, over-voltage/over-temp signal, and LVC signal) and bi-directional serial comms.
I don't have and I've never seen this board (let's call it the I/O board), but I've seen pictures of it.
my understanding is this:
-each VMS board handles 4 cells
-the VMS boards can be daisy-chained (they have two fragile 10-pin connectors)
-these connectors are intended to be used inside a battery pack, and not to be exposed to the user
-the I/O board connects to both ends of the daisy chain (the VMS board string) and "outputs" those two ports to the world using two "rugged", user-friendly connectors (DB-9s). (it also has a couple of over/under voltage leds, I believe.)
-the user can continue to daisy-chain battery packs using these two DB-9s.
WARNING: these DB-9s carry the signals of the 10-pin connectors, and are *not* compatible with a DB-9 PC serial port, neither in voltage nor in pinout.
this means that for example:
-a 36V pack can be made with 3 VMS boards and a single I/O board, using 4 10-way flat cables.
-the user can get 72V by chaining two of these packs together with a (custom) DB-9 cable.
-the user can access all 6 VMS boards via one of the remaining DB-9 ports.
> According to the docs I have, the serial comms are 0-5V TTL, not the -12/+12V levels for full RS-232 comms.
I don't know about this. maybe you can PM the docs, but I don't think ANE wants their info docs publicly posted. I would appreciate if you could post high-res images of the I/O (or "display") board, both sides, with enough resolution to trace its circuitry.
> I also have the USB board in the mail, but didn't know what it did
I understand that the cutoff/USB boards replace the I/O boards in the packs that integrate cutoffs. I believe these boards are either 16V- or 48V-only (as ordered from factory) and thus can't be used in user-chaining scenarios; that's why they don't feature DB-9s. (they do allow access to the serial lines via a USB bridge.)
also, there are at least two versions called SWBOT4801 and SWBOT4802. the SWBOT4801 has less current handling:
SWBOT4801
Max Continuous Discharging Current: 30A (@ 25C)
Max Peak Discharging Current: 60A (1s)
Max Continuous Charging Current: 15A (@ 25C)
Max Peak Charging Current: 20A (1s)
they also don't have the copper bus bars as seen on the pics above.