I am currently developing a BMS which features some exciting stuff and want some design input from you guys.
Features:
Nano size: 21703.6mm.
5-16s configurable via PCwritetool.
Balance current: 45mA .
Super affordable $20+.
Balancing led indicator.
15A charge current.
Background
Nowadays, VESC comes with integrated power switch, therefore a traditional BMS with discharge control is really redundant and even dangerous, cause it may decouples the battery from the ESC when the regenerative current kicks hard and trigger the OV protection in the BMS, some cheap Asian BMS amazon has been reported to be unreliable, I have some experience in designing BMS ,that’s why I am starting this Nano16s project.
Progress
Now I have made the first version of it and sent it to SMT, samples be available in end of May
Looking forward to seeing how beta-testing goes, good luck!
I would love to see a button or link on that settings screen that brings you to a page with a short explanation of each acronym/setting. That will save you from having to respond to a ton of questions and will help reduce mistakes made by users.
Questions
1.Do you want a sandwich aluminum CNC casing if it costs 10$ extra and make the total thickness to be 5mm
2.Is 15A charge really a thing? what kind of charger you guys use for fast charging?
What is the estimated max component/junction temperature (or design goal) for the board in an enclosed space without the aluminum case, assuming worst case balancing resistor heat load?
If a user has a large pack, 8P or 10P or higher, then 15A isn’t very fast charging at all.
Yes Bluetooth BMS is fancy but I think that a good BMS is a BMS you never need to check or monitor, plus the balancing led has already indicates the health status of a pack, I want to make this project essential and affordable, so currently, it will not have BT connection, but if I were to design a monitor app, it will be adding a MCU and can bus that talks to vesc and send it into vesc app.
consider that the tja1051tk3 canbus chip is almost 10$ a pop and the MCU is out of stock everywhere, that would not be available at least in 50 weeks, BT is out of our scope ATM.
I agree with what you said. There has been a few times where I’ve built batteries and my customers were able to monitor the cell voltage levels on their first charge cycles only to notice that one group is draining and charging faster then the rest, a clear indication of either a bad cell or loose welds. In all 3 cases it was welds that broke loose from the negative electrode on one of the cells in a pgroup. I was able to repair the pack immediatly and all 3 are still in use in perfect health.
I understand the chip shortage throws a wrench into the who BT/other communication methods buisness…but I think its an extremely good idea to plan to add these function to any future bms being developed…we no longer live in the stone age, its time to advance our battery technology. 95% of batteries I build use a smart bms, and I plan to make that 100% in the near future.
Also I like 16s…but why stop there? We have 18s capable controllers, maybe I dont understand the engineering behind it, but it is difficult to go to 18s from 16s?
to have it CAN capable and then read it via metr/ilogger/freeskate tracker sounds like the best option to me.
Also i’m not a found of multiplying 2.4ghz chips arround my remote receiver when i can do with one
Agreed with the above!
The issue is us the builders and our application that involves a ton of vibrations. Being able to monitor individual p-groups is the way forward for sure.
And to be fair the daly bmses are on the smaller side and cheap and often good enough for the cheapskate.
bluetooth bmses on the other hand could be made smaller and nicer I think and might be easier to compete against price/performance.
You’d be surprised how hard it is.
Many commercially available BMS controllers max out at 15 or 16 cells because this is what the overall BMS market needs. Most of the individually monitored modules or full battery packs just don’t have more cells in series than this.
There are EV pack controller chips designed for putting in series, to support up to hundreds of volts for the pack, but these are more difficult to design with and use, require more space, and raise the cost of the BMS.
A custom design using just an MCU for BMS monitoring and control can easily support 18S, or more. But that requires writing of the software and epic levels of testing since this is a safety-related application. Using BMS controllers instead can add a significant degree of pre-tested safety to the design and speed up the time-to-market.
Since esk8 is a low-volume market, and 18S and higher packs are just a small part of this small market, it can be tough to justify the cost and time needed to design a high s-count BMS. It will happen, but IMO there just won’t be a lot of people working on it for a while. Not until 18S becomes the new 12S.
