A quick update on this build. After the failed attempt to convert to CA3 control, the bike has been back to normal commuting duties and covering around 150km a week. Drive has been faultless over the last 1500km and with close to 3500km on the clock, continues to be as quiet as the day I got it.
However, the 15S LiPo battery set-up is not ideal mainly due to it being to higher voltage for the BBS drive. It takes a bit of management to ensure I don't charge over 61.5V and means every time I balance charge it with my RC chargers, I am stuck with a pack at 63V that then needs to be drained down by some other means back to 61.5V to work with the BBS. Also range is a little light on with only 250Whrs usable.
So I decided it was time to get with the strength and give some 18650 cells a go. Ordered some new reclaimed LG 2900ahr cells from this thread
http://endless-sphere.com/forums/viewtopic.php?f=31&t=61608 and BMS from EM3ev with the plan to build a 14S 4P setup.
Unfortunately I will need to go down the path of soldering the pack as opposed to spot welding but I have a good high powdered iron and experience soldering batteries from previous projects.
Biggest challenge will be building the enclosure in such a way that it it takes up the least amount of space possible and provides an OEM look to the bike. Also, I want to avoid the need to have any aluminium welding done.
Anyway, here is the design shape I have come up with at this stage. This bike handles great and should be even better with the low mount pack.