Step 3 - BMS Connection: As previously noted, I went with a TinyBMS for this build. The main drivers for my BMS decision were 1) flexibility (tons of analog and digital pins to play with), 2) quality (this thing is really pretty...), 3) fit for purpose (I'm using all external relays for LVP, HVP, and LTP, so I wasn't concerned at all about current ratings), and 4) excellent documentation.
First step (after reading the manual) was to get the wiring harness sorted and installed, starting with the balance leads. For this temporary setup, I just added a second nut to all my negative terminals and sandwiched the tinned leads between the two nuts. I'm going to have to replace a lot of the leads, so didn't want to waste my time with connectors. The 300mm leads provided with the BMS just barely made it to the oposite corners of my 2 x 8 configuration.
Next, I soldered on the B+ and B- leads. I went with 22awg wire for these, as no current (beyond what's needed to power the BMS) will be passing through them. From there, I connected up B+ and B- leads to the battery terminals and it fired right up. I then installed the balance lead connectors, external current sensor, and USB cable. After a quick driver update, the BMS connected to the Battery Insider application automatically and all my cell voltages popped up. I was quite please that there were no issues here, considering I'm running the application Windows running on Parallels on a Macbook Pro.
Next, tinkered with the settings on the BMS to get it set up for my 'testing configuration'. For this initial setup, I'm using the BMS in single-port mode with the switch set to the AIHO1 pin. It took me a bit of testing to figure out exactly how these pins function. I'm probably going to get the terminology wrong here, but I believe these relays are controlled as 'low side' switches, in that they can take 48v power from anywhere in the system, and the switch connects or disconnects that supply to ground. For my setup, I'm using a 5A Relay with 48V input (
Crydom EH10F5) wired in series with the inverter switch. I'm pulling the 48v 'signal' directly from the switch itself, so i only need one 'low side' wire running back to the BMS. I've tested it out, and it seems to be working fine (ie, it turns the inverter off if there's a fault detected.
Here's a few pics (so you know I'm not just making this all up...):
View attachment 34557 View attachment 34559
View attachment 34560 View attachment 34561