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Engine bonding question

B

bobct

Advanced Contributor
Should the engine block be tied to the bonding system or the DC bus bar (mine is behind my battery box)?

Each of my engines are done differently. I replaced all of the connectors a few years ago and just copied what was done previously. I just noticed that each one is different. The factory wiring diagrams don't show any bonding connection points so I'm unsure when it was added.

Thanks
Bob
 
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Your engine blocks provide the 12 vdc "System Negative Common". All 12 vdc negatives should terminate here.
Both engines will be joined via a large Negative cable.
Key word "negative" (not ground).

Your 120 vac S/P system has a hot, a neutral and a ground.... key word "ground".

These two entirely different systems can be joined via galvanic isolation.


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I became a trained production heavy equipment mechanic in the late 60's.
My training included pneumatics, hydraulics, power train components, etc., etc....... including 12 and 24 vdc electrical.
No where in my training was the DC Negative voltage spoken of as a "Ground"!

Now industrial or residential AC current does use an Earth Ground!

My pet peeve, perhaps! :(



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Kim.... this thread is regarding a question about a bonding system between the 12 vdc and 120 ac systems.

The author of the "Black Box Techniques" article refers to a 12 vdc "ground".
Ground refers to "Earth Ground".

I have no arguement when speaking of AC current...... but I do when speaking of DC current.

Stand-a-lone 12 vdc circuits have no need for an earth ground.... only a Positive and Negative.


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kimcrwbr1 said:
1.... so all the 12v dc is tied to the neg bus bar and then to the battery neg.

2..... then the 120 vac system ground is bonded to the bus bar using a galvonic isolator is this correct?
Click to expand...

1..... No..... all item Negatives for any 12 vdc circuit would connect to the "system neg common" (engine) ...... be it to a Neg Bus Bar or other.
Then the continued Negative circuit would run to the - Batt terminal.... of which is also where the "Shunt Resistor" would be installed if an Amp Hour monitor is used.


2..... I believe so.


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Bob:

The engine blocks should be connected to both.

It isn't uncommon to find many installations where one connection is used for both purposes...that will be adequate as long as the interconnecting copper is in good shape. Dedicated connections are preferred but cost more...as long as your zincs are working and you have no other issues, your system is probably fine.

On a side note, if an AC source is 'dirty', a 30 uF cap will only mitigate the high frequency component of the noise....and the processor on the control board doesn't give a hoot about the AC, only the DC that provides its working bias; if thats where the noise is (processor's DC supply) then you need to fix the power supply's filter section.
 
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