Inverter grounding and other details


Jose Venegas
 

 I am installing BB lithium batteries and a new 5000 VA 24-240 v 50 hz Victron inverter.  I decided to avoid the temptation of installing an Inverter/charger because of the 50 to 60 Hz issues when using it in the Americas.  
I plan is to pass the 220 V 50 Hz cable from the inverter to the engine compartment and add a third outlet to the box that has the 220 V and 110 to 220V  transformed outlets.  This will allow me to power all 220 V outlets of the boat, plus air conditioning, microwave oven, washing machines, and water maker (obviously not all at the same time).  without having to rewire the 220 circuits. Also obviously, I will not be turning on the battery charger while the inverter is ON. 
With this approach, I expect that the system will switch automatically to the generator, as it does when the boat is running on shore power.  Yesterday I tested that the water maker was able to run under shore power without circuit breakers going off which suggests me it will be able to run with the inverter.  How much current will it draw and how long will the batteries be able to run it will have to be determined.

I found on this group a long discussion about the independence of AC and DC grounds in the SM Amel and long discussions about installing inverter/chargers but  I STILL HAVE A FEW QUESTIONS:

1) Is there something wrong with this approach? have I missed something?  For example, do the sudden shut down of the inverter AC output by the relay switch at the start of the generator damage the relay switch, the inverter, or the lithium batteries. Of course, to be safe I could turn off the inverter and or disconnect its AC output from the box before turning on the generator but it would be good to know is something is fundamentally wrong with this approach..    

2)   What to do with the AC "ground" 220 V connection from the inverter?  The inverter has the metal case connected to the ground of the 220 cable output and allows this ground to be connected to the neutral.  I have disconnected this and am not planning to connect the case to the bonding since that would connect the AC ground to the DC bonding that I have read is a NO-NO.  Alternatively, I could have the case connected to the DC negative or completely disconnected from everything.

3)   Any ideas where to pass the 220V cable from the battery compartment to the engine room.  There are several DC battery cables running through what looks like epoxy resin to prevent water from flowing between the two compartments.  Have anyone drilled a new hole along and above these cables?  If so, was it started from the engine compartment to avoid damaging of tubes and cables in the engine compartment?

4) I am planning to connect the DC cables from the inverter to the large DC switches from the batteries.  Are these switches large enough to handle the current if one does not use heavy current DC motors such as the bow thruster while running the inverter at full power?   The 5000 VA inverter requires a 400 amp fuse. 

Any thoughts or suggestions will be greatly appreciated.

Jose Venegas
Ipanema  SM2K 278


 

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