Non-zero voltages (?)
- Thread starter Dan
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Bad ground...
Or you have what is known as a ground loop. A ground loop is caused by having separate grounds that are not at the same zero-volt potential. All grounds should lead to one grounding point. Regardless if you are using a grounding bus bar, it should lead to only one central ground point. You need to find the cause quickly as you have current flowing in your boat. You did not specify if it was AC or DC. I suspect DC, but one never knows.
Or you have what is known as a ground loop. A ground loop is caused by having separate grounds that are not at the same zero-volt potential. All grounds should lead to one grounding point. Regardless if you are using a grounding bus bar, it should lead to only one central ground point. You need to find the cause quickly as you have current flowing in your boat. You did not specify if it was AC or DC. I suspect DC, but one never knows.
Ground loop
Brian Thanks. That's a very helpful root cause. I'll check it out. Any advice on a strategy as to how to do that? The grounding bus bar is the one at the panel, I assume. The boat has significant corrosion in places - I assume it's related to this. And your suspicion is correct -- it's on the DC side.
Brian Thanks. That's a very helpful root cause. I'll check it out. Any advice on a strategy as to how to do that? The grounding bus bar is the one at the panel, I assume. The boat has significant corrosion in places - I assume it's related to this. And your suspicion is correct -- it's on the DC side.
I would start off with things recently added...
Or things that are easy to depower. Such as radios, stereos, TVs, anything that has a power cord connected to the back of the unit. While doing so, check with you meter at a location you know there should be no voltage present, such as a fuel tank, and ensure your meter is set to DC voltage. After depowering everything that is easy to get to, start with things that are a little more difficult. These would be connections at the distribution system. Then work your way back to the inverter (if you have one), battery switch (remove the path from the switch to the distribution panel), charger (either the AC side or the DC side), then the batteries themselves (one ground at a time). Find the single ground point and ensure it is clean and makes good contact. Look for any device that appears to be grounded some place else other that a common ground point. Look for corrosion build-up points between a (+) and (-) connection. Solar power? Check to see that you are not getting any reverse flow back through the ground. A bad diode could cause that. I'm not sure if that is even possible now adays, but it sure was 20 years ago. Key here is to be methodical in you search. Don't jump from item to item. Find out all the things are are using 12vdc and check each one. Hopefully someone might have other suggestions. Good luck.
Or things that are easy to depower. Such as radios, stereos, TVs, anything that has a power cord connected to the back of the unit. While doing so, check with you meter at a location you know there should be no voltage present, such as a fuel tank, and ensure your meter is set to DC voltage. After depowering everything that is easy to get to, start with things that are a little more difficult. These would be connections at the distribution system. Then work your way back to the inverter (if you have one), battery switch (remove the path from the switch to the distribution panel), charger (either the AC side or the DC side), then the batteries themselves (one ground at a time). Find the single ground point and ensure it is clean and makes good contact. Look for any device that appears to be grounded some place else other that a common ground point. Look for corrosion build-up points between a (+) and (-) connection. Solar power? Check to see that you are not getting any reverse flow back through the ground. A bad diode could cause that. I'm not sure if that is even possible now adays, but it sure was 20 years ago. Key here is to be methodical in you search. Don't jump from item to item. Find out all the things are are using 12vdc and check each one. Hopefully someone might have other suggestions. Good luck.
GuyT is right. The loose definition of a
capacitor is two conductors separated by insulation. A pair of wires meets that definition. Adding a 1k resistor will in effect short out the capacitor and not have an adverse effect on the rest of the system.
capacitor is two conductors separated by insulation. A pair of wires meets that definition. Adding a 1k resistor will in effect short out the capacitor and not have an adverse effect on the rest of the system.
Hi Dan, the distribution panel ground bar...
at the navigation station and all other system ground cables (windlass, inverter, distribution panel, etc.) on our boat connect to the two house bank 8D ground terminals. The main ground cable from one of the 8D house bank batteries goes somewhere, but I have not found where it terminates, yet. It is not on the engine or transmission, nor keel bolt, but it disappears into one of the stringers. Terry
at the navigation station and all other system ground cables (windlass, inverter, distribution panel, etc.) on our boat connect to the two house bank 8D ground terminals. The main ground cable from one of the 8D house bank batteries goes somewhere, but I have not found where it terminates, yet. It is not on the engine or transmission, nor keel bolt, but it disappears into one of the stringers. Terry
Dan...
You don't have to have long cables. Just take a measurement at a place where you know there should be no voltages. Leave your meter there and then start disconnecting things, then go back and see if the voltage goes away. How did you find the stray voltage? Did you connect one side of your meter to a ground point and the other side to something that was grounded? If that is what you did, I will continue to think ground loop. However, if you checked between ground and a (+) side when the the circuit breaker was "off" then I would lean towards Guy's theory. Good luck
You don't have to have long cables. Just take a measurement at a place where you know there should be no voltages. Leave your meter there and then start disconnecting things, then go back and see if the voltage goes away. How did you find the stray voltage? Did you connect one side of your meter to a ground point and the other side to something that was grounded? If that is what you did, I will continue to think ground loop. However, if you checked between ground and a (+) side when the the circuit breaker was "off" then I would lean towards Guy's theory. Good luck
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