IMO the most reasonable BMS to use with a VESC today is a charge only BMS (like the D140).
With the VESC you can limit max current and set a low voltage cutoff.
The only feature left to eliminate the large and expensive high discharge BMS raison d’être is to also read the cell voltages and cut off if they fall below a user set threshold.
Apart from space and money savings, another advantage is the possibility to have a slow cutoff saving people from kissing the road.
Might there be a way to integrate a 12pin connector that reads the cell voltages?
Ideally something to retrofit existing VESCS. If that is not possible, could it be added to future VESC dev @Trampa?
I have great respect for the DieBieMS - it is great for its purpose. But for a build where space is sparse, or for small batteries, or for lazy people, it’s not a match.
getting anything merged into official VESC repo is impossible btw. vedder is terrible at maintaining his project. and Frank is too busying protecting his profit.
Ideally I would like to be able to monitor the cell voltages on my phone via the Bluetooth adapter on the VESC. Even if there is no cutoff, just being able to read them without opening the enclosure is worth gold.
Actually - it IS kinda crappy in one aspect. The voltage divider loses resolution at the higher cell counts but as whole it is pretty accurate. It would definitely highlight a runaway cell.
I assume that the flexiBMS already has accurate readings built in as it needs to balance - if it also could display them, we’re all set for the first part.
Next on the wishlist would be to communicate with the VESC (or have an other means for soft cutoff)
BMS functionality doesn’t belong in the motor controller. Safety cutoffs yes, but not cell monitoring and all of that. You can get a lot of that kind of stuff over uart or Bluetooth with some BMSs. But all you really want is someway to look at it all in the same app, so what you really need is an app that can do vesc shit and BT BMS shit or connect to the BMS over uart or can bus through the vesc.
you’d have to write your own app or get somebody to do it.
Honestly, I would be 80% happy if I could just monitor my cell voltages. Either via a display or app.
If I just check in occasionally I can prevent the pack from getting unbalanced or diagnose issues.
For me, a flexiBMS + cell voltage display would be a killer combo.
I know. I actually have one coming in.
The drawback of that smart BMS is:
Discharge current is far to small for any reasonable battery. So you have to bypass it.
Thus, it becomes a oversized charge only BMS with Bluetooth.
It they offered 80A+ options, or, ideally, a much smaller discharge only option, I wouldn’t have started this thread.
