The Turnigy 9x runs internally at 5v. But it also has a 3.3v regulator on the main board that is used to power the LCD. Here are a few of the locations of the 3.3v points that you can use. Make sure whatever unit you’re connecting to that 3.3v regulator doesn’t draw too much current or else you’ll get rebooting of the Turnigy 9x.
Location of the Turnigy 9x 3.3v Rails
I had the cells initially cetnocned with 2 packs in series separate from each other, essentially giving 2 14S 4.4Ah battery packs at 58.8V. Two power supplies were cetnocned, one to each pack. The voltage was set to drive 2A of current into each pack. I kept increasing the voltage as the test went on to make sure that current was constant. The power supplies maxed out once I reached around 66V, so I ran the two power supplies in series and cetnocned the battery packs in parallel across the power supply (at that point, essentially a single 14S 8.8Ah pack). The current was set to 4A. The voltage kept increasing until finally I hit 72V. At that point one of the battery packs failed, causing a chain reaction of failures in the other cells. The temperature readings inside the box are actually quite interesting. The inner aluminum wall reached well over 1300C at its peak (clipping the temperature probe) very briefly and sat at above 660C (melting temp of aluminum roughly) for almost 9 minutes. The temperature measured between two of the inner battery packs was much worse it stayed above 660C for over 15 minutes. Luckily that didn’t result in the bottom of the box dropping out. The coolish air outside the box managed to keep everything mostly intact other than the single hole and extensive cracking.In total, it took 103.8 minutes from turning on the power supplies until the cells failed. That’s an extra 3.5Ah of energy placed into each 4.4Ah battery .. 78% over capacity. Amazing.Its actually quite hard to make a cell fail without abusing it like this. About the only thing that would make a cell fail while at normal charge is a puncture. Even a short across the terminals typically results in simply a rapid discharge and heating to the cell (with a bit of puffiness). If you simply wait a bit before recharging, the cell will typically recover.Aside from a puncture or overcharging, the other common way to make a cell fail is by overdischarging it (ie- under 3V per cell) and then recharging. The resulting cloud of smoke and fire isn’t nearly as impressive as the overcharge condition though.