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Downeaster 08-28-2012 03:45 PM

Busbar sizing
 
Hi all - I've learned so much on this forum. Thank you all for your great contributions and dialogue.

I am installing a Victron battery monitor and am debating between the Blue Sea 250 amp Maxibus and the 150 amp version to consolidate the ground wires in front of the shunt. The 250 amp with cover is LARGE and I'm not sure I can fit it very effectively in my battery compartment.

My static loads will never exceed 150amps (no inverter or heavy loads) so I'm only wondering about the starter motor and electric windlass. I suppose that, if I somehow managed to crank the engine and haul in an anchor at the same time that the peak current could well exceed 150 amps. But I can't imagine the two loads being concurrently applied for more than 60 seconds. Even that is a stretch I believe.

Seem to me that the 150 amp bus bar (BLU-2307) with cover should be plenty. But then again I have been going to the trouble of using 1/0 wiring in the battery box for jumpers between my new 6vs wired in series.

Any words of wisdom?

Downeaster

ebs001 08-31-2012 06:30 AM

Re: Busbar sizing
 
Bussbar ratings are for continuous loads. Motor's peaks are momentary at start up, although you can put considerably higher load on the windlass circuit when approaching its maximum weight rating, like with an anchor stuck on the bottom, but that current draw will be of short duration as well. The rating of 1/0 wire is 150amps.

Downeaster 08-31-2012 09:33 AM

Re: Busbar sizing
 
Thank you ebs001. I must be a nerd because I've really been waffling on this. Right now my plan is to use the 250amp because it is, as I've discovered, similar in size to the Victron shunt. They are both basically too large to cover effectively in my battery box so i think I'll leave them without covers and focus on covering all the positive studs and terminals. I was also surprised that the shunt terminals are 3/8" versus 5/16" requiring jumper cables with different sized lugs so fyi for anyone planning to install a Victron battery monitor.

mitiempo 09-01-2012 10:31 AM

Re: Busbar sizing
 
Quote:

Originally Posted by ebs001 (Post 916339)
...The rating of 1/0 wire is 150amps.

Actually 1/0 is rated for 285 amps outside engine spaces and 242 amps inside engine spaces.

ebs001 09-01-2012 11:27 PM

Re: Busbar sizing
 
Quote:

Originally Posted by mitiempo (Post 916742)
Actually 1/0 is rated for 285 amps outside engine spaces and 242 amps inside engine spaces.

Yes, you are right I should have been using the free air rating.


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