No Negative Battery Switch or Battery Selector

[mitiempo]

Originally Posted by svHyLyte

Bill-We have accomplished the same thing with a momentary push button switch on the instrument panel that activates a solenoid that links the house batteries and start battery to allow one to use the house batteries to start the engine if necessary.

Ideally you want to start the engine with the house bank by itself if the start battery is unable to do so. It is never good practice to combine a good bank with one that is dead or very low in voltage.

[Panope]

Originally Posted by funjohnson

Trying to follow your layout and would love to see what is doing what. Please post once you get it labeled


edit: looks like the left switch is for start bank, center is to combine, right is house bank, and the bottom switch is for neg off. Do you have the neg floating? If so, does it connect to both banks before the switch?

Matt

Matt, You have correctly identified the switches.

I am not sure what you mean by "floating" but I will say that I tried to isolate every electrical component from the hull. I say "tried" because my efforts to isolate the engine block was not 100%. Not sure where the "leakage" is coming from (Cooling water? Wire in hoses? Salt crystal "bridges"? etc...). Efforts to isolate house consumers was 100% successful.

Both House and Start battery negatives are connected permanently to the (pictured) negative busbar. The house consumer negative is also connected permanently to the bus. The negative switch disconnects the engine block (only) from the bus.

Steve

[Dsanduril]

Many European boats that I have seen have a DPST master switch that breaks both positive and negative with a single switch. The most common reason I have been given is lightning protection, the negative side on many boats is frequently bonded to many things (engine block, thruhulls, maybe rigging, etc.) and lightning damage probably occurs more frequently through the negative side than the positive. Doesn't help anything (like most of our most expensive toys) that has other connections (antenna, signal wires, etc.), but for solely electrical equipment breaking both sides does provide some protection, with the negative open as well your equipment is no longer bonded to the boat's ground when the bolt hits.