The spikes you’re seeing are the charger’s way of saying “I’m under stress.” When the load suddenly demands more current, the internal switching circuitry ramps up, and the supply rail can dip or overshoot before it stabilises. Look for clues: a quick rise in current draws a voltage drop if the internal MOSFETs or the driver’s gate drive are slow; a sudden rise in ripple points to insufficient smoothing inductance or capacitor ESR; a brief overshoot followed by a sharp crash can mean the charger’s protection circuitry is tripping. So check the current sensing resistor, the bulk capacitors, and the switching frequency—those are the evidence you need to track down the culprit.