1. Voltmeter attached to red and black
2. Did the wiring as described by Y0SH1zzzx
3. Voltmeter show ~47V for 2 seconds
4. Voltage is dropping to ~31V for one second.
5. Steps 3 and 4 repeating over and over again (Voltage rises and drops again).
Why do I observe this behavior? Because there is no load attached?
How do I charge the battery? Do I keep your wiring (Y0SH1zzzx) and simply attach my charger to the red and black cable?