For monitoring I'll be installing my own design of pack monitor, which I already have a Yahoogroup for https://groups.yahoo.com/neo/groups/CellMonitor/photos/photostream
I'll be able to trip low voltage and high voltage alarms and use them for the respective purposes of cutting down the current, or ending the charge cycle. Adding logging is going to be easy so I will be able to identify any modules with a wayward trend over time.
There is no individual fusing per cell. Each submodule of 21 cells has 'robust' inter-cell tinned strip, but an accident in handling where one pack's terminals rested against my belt buckle caused a bit of a fright (!) and in that case the steel strip burst between a couple of modules. The load is then transferred to other modules and in a short time they would all blow. Each battery has it's own 200A Bussman fuse too. All low current feeds from the batteries have inline blade fuses and the 12V key circuit is fused too.
Would I use individual fusing per cell ? I think it is not unwise to do so. Then again every single pack of 6,8 or 10 cells which I dismantled all had failed cells and yet there was no sign of any fire risk, only in a couple of instances did a cell's plastic sheath seem to have melted, or deteriorated due to corrosion as a result of an electrolyte leak.
It is my understanding that Tesla use fusing at cell level, but then again i believe they use the very latest technology very high level discharge rate cells and so there may be a case there where fusing is much more important.
I plan to install temperature monitoring too and integrate that with the main safety circuit, which will consist of a charge protection relay (physically installed now but not wired in), a throttle inhibit and a warning panel or LCD information display.
The maximum pack voltage is theoretically 84V, but I don't intend to charge above 82V (4.1V /cell) and the onboard charger only brings the pack up to 80V (4.0V /cell ) charging to a 'cautious' level like this I believe can increase the life expectancy of the cells and reduce cell stress in return for a very slight reduction in range.
The next job is to clad the main battery pack and add some weatherproofing, and also add splash shields around the motor. (not forgetting the battery monitoring electronics required). The front forks need new seals but that's trivial.
From the test runs which I've already made, running the bike backwards and forwards at full throttle on the test road I use, the sag of the battery voltage is quite acceptable and if I use a maximum of only 80% throttle the sag is very small and the current stays below 150Amps. At cruising speed the current drops away nicely. I'll need to gather more accurate information, but the volt/ammeter died a couple of weeks ago and the replacement hasn't arrived. The last time I tested the bike I started with a voltage of 82V and took it for about ten full power runs over a few hundred metres each time, and ten minutes after returning home the voltage was still above 80V, representing a drop from 4.1V to 4.0V per cell.