Engine and Service Battery circuits Isolated


Andrew & Kate Lamb
 

I recently installed a Victron battery monitor which also has a facility to monitor the engine battery voltage however I discovered that the -VE of the engine battery and the service batteries are not linked. Does anyone know a reason why this should be and see a problem with why they should not be tied together - I would have thought from a "grounding" point of view it would be better for them to be linked?


thanks


Andrew & Kate

S/V Ronpische

SM 472


Alan Leslie
 

This is the Amel system.


The -24V line is not connected to "ground" at all.

The -12V starting battery line is only connected to ground during starting of the engines.


All the -ve lines from 24V equipment return to the -ve battery terminal of the 24V bank.


All of the metal equipment that comes in contact with salt water is grounded by means of green/yellow wires that are all connected together at a bracket in the sump. This bracket is connected to a keel bolt and also to the zincs on the rudder. There is no zinc in the Yanmar engine, although there is one in the Genset.


I can sort of see some logic in this, but what has me also mystified is that all of the standing rigging is isolated from ground....I don't know if anyone can explain why that is a good thing ?


Cheers

Alan

SV Elyse SM437.


Andrew & Kate Lamb
 


Ok sounds like I should leave well alone - in our last boat the -VE poles were tied together between the house and engine batteries with one common (black) master switch and the positive poles had separate (red) master switches the combined circuits were isolated though. I am keen to monitor the battery state as the only charging appears to be from (I think) the genset or engine alternator and given that both of these need the battery to be charged to start... - there appears to be no charging from the shore power - I think I will install a separate battery monitor, to monitor the health of the engine battery. Good tip on the jump leads - I did come across these at the bottom of a locker.


Andrew & Kate

Ronpische

SM 472

Canet-en-Rousillon


Alan Leslie
 

Personally I wouldn't worry too much about the start battery, I don't.

The main engine has a dedicated alternator to charge the start battery...so every time you run the engine the start battery is charged...just like your car...do you have a monitor for that ?....I'm guessing  the answer is no...


Same with the genset...there's a dedicated alternator that charges the start battery (same battery as the engine charges)


So in total...don't worry about it...just keep it topped up with distilled water.....or better, do what I'm gong to do and replace it with a no-maintenance AGM battery


Cheers

Alan

SV Elyse SM437