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Battery Monitor + Alternator

tadslc

Member III
Just installed a Victron BMV600 battery monitor and everything is being read except the alternator charge.

Per another excellent How To by Maine Sail he describes the install and also touch’s on my dilemma-
“Keep in mind that many marine alternators are case grounded and thus the system ground, which on most boats is the engine block, is the ground path for the alternator. While I much prefer an isolated ground for alternators many boats just do not have alternators with this feature and they use the case as the ground. Due to this, the ships main ground connection should be connected to the -LOAD side of the shunt and NOT ahead of it or on the -BATTERY side.”

My question is: Where is the ships main ground connection? I thought I had taken all the grounds off the motor and ran them through the –Load side of the shunt but obviously I missed one.

Any ideas?
 

Maine Sail

Member III
Most boats use the engien as ground. This ground point needs to be on the -LOAD side of the shunt as do all other negative connections.

Your problem could be the hot side of the alternator too. Where does your alternator wire to? Is it connected to a 1/2/BOTH/OFF switch? If so and you select the opposite bank the alt will not be read by the house bank.
 

tadslc

Member III
Thanks, My alternator is wired to a 1/B/Off switch (Not 1/2/B/Off) and grounded to the engine. I have a neg cable that runs from the engine to a neg terminal on the battery. Should I take this off the battery and put in the -Load side of the shunt?


Thanks,
 

Maine Sail

Member III
I have a neg cable that runs from the engine to a neg terminal on the battery. Should I take this off the battery and put in the -Load side of the shunt?


Thanks,

Yes you'll need to move it. NOTHING goes before the shunt or it will not work properly. ALL negative wires and ship ground go on the load side of the shunt not the battery side. Even your second bank negative wire should not be tied to the house bank negative terminal.

Here's what it looks like in a boat. Please ignore the wing nuts! Photo for illustrative purposes and only during test fit:
133431842.jpg

133431843.jpg


Bank #2 negative/ground ALWAYS goes on the load side of the shunt as selecting the ALL position can transfer Ah's between banks. If not counted by the monitor, your readings will be off after selecting the ALL position.

P.S. The ONLY time another wire is attached to the house bank NEG post is if it is a parallel or series parallel bank and those connections are PART of that bank.

NOTE: The printed circuit board on the Victron shunt was flipped in order to orient the compartment wiring the way it is. In the normal position the -LOAD and -BATTERY sides would be reversed.
 
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tadslc

Member III
Much thanks,

Got it all run this weekend and it works like a charm.
It really couldn't be simpler, ALL negative grounds go to the Load side of the shunt except for the main battery bank negative you're wanting to monitor and this went to the Battery side of the shunt.

As for bank #2, do you want to include this in your total amperage total? I understand that if I ever selected Both (1/Both/Off) it would throw the amp reading off but with my setup, selecting Both would be a a last ditch effort to get the engine started.

Thanks,
 

Frank Langer

1984 Ericson 30+, Nanaimo, BC
Maine Sail,

In the first picture above, why can you not attach the red positive wire and the orange wire (bilge pump?) directly to the battery post with the wing nut (or a regular nut with lock washer)? What is the purpose of this extra attachment device you show?
thanks,
Frank
 

tadslc

Member III
Frank,

The orange/red wire you see is the power wire for the battery monitor and is to be wired directly onto the positive main battery bank. I don't see the red wire you refer to.


Tad
 

Maine Sail

Member III
Maine Sail,

In the first picture above, why can you not attach the red positive wire and the orange wire (bilge pump?) directly to the battery post with the wing nut (or a regular nut with lock washer)? What is the purpose of this extra attachment device you show?
thanks,
Frank

#1 You can attach the positive lead from a bilge pump to the positive post of the battery. You can not however connect the negative lead to the house bank negative post or it will not be measured by the shunt.

#2 Wing nuts have been verboten now for a number of years and battery manufacturers no longer ship batteries for boats with them. People assumed you could just tighten them with your fingers and that is usually never enough torque, hence the move to standard nuts and locking split washers or nyloc nuts.

#3 That red/orange wire is the sense wire for the battery monitor and its fuse. I don't like the fuses Victron ships so I install a better quality in-line ATC fuse. I have had three Victron in-line fuses DOA and never had one of this type fail.
 
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