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Old 03-27-2012, 09:07 AM   #1
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Battery monitor

I bought a Xantrex Link Lite batterery monitor and I will be installing it soon. I'm looking at the wiring diagram and there is something I don't understand: why is the 2nd battery negative connected at* the end of the shunt (and not on the same terminal as the main battery)?
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Old 03-27-2012, 10:52 AM   #2
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Battery monitor

Quote:
Fotoman wrote:I bought a Xantrex Link Lite batterery monitor and I will be installing it soon. I'm looking at the wiring diagram and there is something I don't understand: why is the 2nd battery negative connected at* the end of the shunt (and not on the same terminal as the main battery)?
Does the system*monitor one or two batteries?


-- Edited by JD on Tuesday 27th of March 2012 10:53:18 AM
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Old 03-27-2012, 11:57 AM   #3
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RE: Battery monitor

Two batteries, the second one being optional.
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Old 03-27-2012, 02:21 PM   #4
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RE: Battery monitor

Connected that way the monitor will read voltage only on the auxilliary battery. There's a variety of reasons why you might want (or not want) that but that's what you'll get if you wire it that way.
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Old 03-27-2012, 03:26 PM   #5
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RE: Battery monitor

Quote:
bobofthenorth wrote:
Connected that way the monitor will read voltage only on the auxilliary battery. There's a variety of reasons why you might want (or not want) that but that's what you'll get if you wire it that way.
Not sure this is correct. The voltage will be*read on both batteries (small wires going from the positive posts to the device. The shunt is to read the amperage...
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Old 03-27-2012, 04:17 PM   #6
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RE: Battery monitor

Read the manual.* You can't measure amps unless they pass through the shunt.
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Old 03-27-2012, 04:30 PM   #7
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RE: Battery monitor

And your point is?
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Old 03-27-2012, 04:39 PM   #8
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RE: Battery monitor

Eric,

The system will read voltage from the House (H) and Start (S) batteries, but will only read current flow into and out of the H batt and SOC of the H bank.* That is where the shunt comes in.* The current flows from the bottom of the shunt (as pictured) to the top of the shunt.

If the S batt neg was connected to the incoming (bottom) side of the shunt, the Link Lite would read the current from both batts and not give you the accurate SOC of the H bank.* By connecting the S batt neg downstream from the shunt, it will not count that current as having come from the H bank.

*

*
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Old 03-27-2012, 04:40 PM   #9
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RE: Battery monitor

Quote:
bobofthenorth wrote:
Connected that way the monitor will read voltage only on the auxilliary battery. There's a variety of reasons why you might want (or not want) that but that's what you'll get if you wire it that way.
*Actualy the shunt would be reading the main battery.* It's ground goes to one end of the shunt and the ground for all systems on the boat goes to the other.* Still*one battery unless the shunt has some internal wiring we don't know about.
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Old 03-27-2012, 04:47 PM   #10
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Battery monitor

Thanks Flywright, makes sense now. I appreciate the explanation.

-- Edited by Fotoman on Tuesday 27th of March 2012 04:57:48 PM
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Old 03-28-2012, 03:21 AM   #11
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RE: Battery monitor

A shunt is not in the start circuit ground because there it could be a FUSE, most will only pass 500A .
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Old 03-31-2012, 10:43 PM   #12
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Quote:
Originally Posted by FlyWright View Post
Eric,

The system will read voltage from the House (H) and Start (S) batteries, but will only read current flow into and out of the H batt and SOC of the H bank.* That is where the shunt comes in.* The current flows from the bottom of the shunt (as pictured) to the top of the shunt.

If the S batt neg was connected to the incoming (bottom) side of the shunt, the Link Lite would read the current from both batts and not give you the accurate SOC of the H bank.* By connecting the S batt neg downstream from the shunt, it will not count that current as having come from the H bank.

*

*

That is the correct answer to the OP's question. Good answer.
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