Stray current

[Stephonze]

I need help figuring out if my battery tender/charger is faulty.
When plugged in, there is about 18volts ac from hull to earth.

I first noticed this tingle while servicing the outboard.

I won’t be plugging in the charger while afloat, is this AC current to the batteries normal?

Charger is the Noco gen 5 two bank charger.
Boat is a 2004 pacific 1925v
Kicker is wired direct to one of the two batteries. But, same condition is evident when charger is only on the opposite battery, that is off on the Perko battery switch.

Anybody encounter this?

Thanks I’m advance.
Jeff