Quote: (How To Measure the Natural Electrolysis Voltage on Your Boat
Yea, another quote!
"A voltmeter with a scale of zero to one volt will measure the natural electrolysis. Place the ground lead of the meter on the motor or the battery ground. Place the positive lead on the stainless steel downrigger cable while it is in the water. The downrigger must be unplugged. The voltage you measure on the volt meter is your boat’s natural electrolysis voltage. When the stainless steel downrigger cable is lowered into the water, the natural ionization between the cable and the boat creates a positive charge of 0.7 to 0.9 volts in saltwater and 0.3 to 0.6 volts in fresh water. This natural voltage is dependent upon salinity and mineral content of the water. Your actual voltage may vary. "
A positive is a good thing, if its not at least 0.7 the first thing you want to do is check, clean or change those zincs! After that if it isn't in that range you could have lot more of a problem than needing a black box! )
Question: Does this apply to an aluminum boat?