3 Volt Lithium battery overcharged under water.<br /><br />The transformer primary voltage was controlled with a variac. <br /><br />A 240 to 152 Volts 1500 VA transformer was used as power supply.<br /><br />The maximum secondary voltage used was 50 Volts ac as can be seen on the voltmeter.<br /><br />At some stage arcing can be heard from the sliding contact in the variac.
