Help with a shunt! (Electrical dilemma)

J

JC93

New Member
Joined
19 May 2020
Messages
5
Visit site
Hi all, I'm installing a Simarine Battery Monitor, The shunt should be installed on the negative side of the battery, I have a wiring diagram here attached but there is a couple of things that's absolutely blowing my mind despite the fact I've been a Generator electrician for about 8 years now.

Not all of my appliances negatives go straight to the battery like the diagram, some are connected to the chassis. How should I connect my shunt in this instance? The first image is the manufactures diagram the second is how I'm currently wired.

I appreciate someone just letting me know where to place the shunt, but if you help me understand why that would be amazing!
 

Attachments

  • Annotation 2020-05-19 182230.png
    Annotation 2020-05-19 182230.png
    133.7 KB · Views: 76
  • Annotation 2020-05-19 190009.png
    Annotation 2020-05-19 190009.png
    129.7 KB · Views: 69
If your appliance negatives go to the chassis the battery negative must also go the chassis in your current setup.

Whatever is connected to the battery negative needs to disconnected and the shunt placed between battery negative and every other negative connection, i.e the chassis connection and every direct to batter negative had to go on the other side of the shunt. No monitor that needs to read battery charge and discharge rates will work if anything other than a single wire is connected between the shunt and the battery terminal.

Assuming that the square in the centre of your first diagram is the shunt, the diagram is correct and your chassis connection will need attaching to the terminal marked "in".

Edit: Why, assuming this is on a boat do have anything using the "chassis" as a negative connection? Its far better to wire everything fully with proper sized cables back to a negative bus bar on the switch panel, thence to the battery negative terminal.
 
Last edited:
You need to disconnect the battery negative and then connect it to the shunt.

Reconnect everything that was connected to the battery negative to the other side of the shunt.

So that ALL current in and out of the battery, flows through the shunt. No exceptions.
 
Thanks, for the prompt reply. I was hoping that was not going to be the answer but suspected it was. Looks like I have some work on my hands tomorrow .
 
JC93 said:
Thanks, for the prompt reply. I was hoping that was not going to be the answer but suspected it was. Looks like I have some work on my hands tomorrow .
Click to expand...
What is this chassis you refer to?
All your circuit negative should ultimately go to a comm point. A power stud or a bus bar. Other battery negatives should connect to the same point.
You should not be using any chassis as a common negative return............. unless you are actually wiring a motor caravan
 
Remove the cable that goes from the battery to the hull, you should not use the hull to carry current.

Disconnect the negative battery cable.

Fit a new cable between the battery and the shunt battery terminal.

Connect the inverter to the shunt load terminal. Connect a new cable from the shunt load terminal to the negative terminals of the loads.
 
The only bit that still needs explaining is why any of this needed explaining if you've "been a Generator electrician for about 8 years now".
 
If you knew what generators I worked on you would understand it's nothing like a yatch. But I didn't think that would have needed explaining.
 
JC93 said:
Everything needs to be re routed through the shunt
Click to expand...

Yes, but did you note that you should not be using the hull for negative connections ? There should only be a single connection from the DC negative, at, or close to, the AC ground connection. Using the hull to carry current is wrong.
 
You must log in or register to reply here.

Other threads that may be of interest

Baggywrinkle
Test run of the Lithium system that has been sitting in my cellar for most of this year.
Replies
6
Views
327
geem
geem

Share this page

Top