DC/DC & Battery monitor shunt placement

Andrew_S

Observer
I'm working on a small 12v system for my homebuilt camper.
It's a basic setup, start battery -> dc/dc ->house battery -> bmv -> accessories (heater, actuators, lights)

Bear with me as this is my first dabble in the 12v realm.
My question is where should the shunt be placed in the system? between the load and the house battery, or as I've illustrated below?

I would love some input from the forum experts as I've come up blank googling this combination. Any other suggestions on the set up would be great as well, bms system required? relays necessary?
Edit* ignore the positive lead from the shunt to dc/dc, that's incorrect, it should be shunt to + house battery.



 

SoCal_80

Explorer
I recently completed a similar install…. I used a Victron Smart shunt and it is on the negative not positive side of the circuit. That said it is connected to the negative side of the “house” battery and ALL negative leads connect to it…Charging, load, etc. If all do not connect through it you will not be able to accurately track both charge and discharge.

I was not an expert either and this was my first endeavor into LIFEP04 batteries, DC to DC charging and using a shunt. The install went great and so far all is good.


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Joe917

Explorer
The shunt connects to the negative battery terminal. There should be no other connections between the battery and shunt.
 

Buddha.

Finally in expo white.
Probably echoing what’s been said above but:
You’re using something like the Victorian 712 battery monitor and you need to wire the shunt?
All negative wires go to one side of the shunt and the other side of the shunt goes to (house)battery negative. In your diagram above you have more than one ground going to your house negative, this is incorrect because those loads will not be measured by the battery monitor. This will make your battery monitor’s percentage readout incorrect.
Also since you are monitoring the house battery I would only ground to the shunt systems that draw off of the house battery, so not the off road lights etc that go to the truck battery.
 

Buddha.

Finally in expo white.
You should only have negative wires going to your shunt, and a temp sensor wire if you’re using one.
 

vtsoundman

OverAnalyzer
Why is your heater and muffler placed up so high? I'd rethink that and place it on the floor. That muffler will get hot and should be outside.

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Joe917

Explorer
For clarity, one side of the shunt connects to the battery. All other negative connections including chassis ground go to the other side of the shunt. The battery's connection to the chassis ( if you need it) goes through the shunt.
 

Andrew_S

Observer
I recently completed a similar install…. I used a Victron Smart shunt and it is on the negative not positive side of the circuit. That said it is connected to the negative side of the “house” battery and ALL negative leads connect to it…Charging, load, etc. If all do not connect through it you will not be able to accurately track both charge and discharge.

I was not an expert either and this was my first endeavor into LIFEP04 batteries, DC to DC charging and using a shunt. The install went great and so far all is good.


Sent from my iPad using Tapatalk Pro
Thanks for that! I was just misunderstanding the negatives to the shunt. Reworked my diagram, should make sense now.

The shunt connects to the negative battery terminal. There should be no other connections between the battery and shunt.
Thank you for clarifying, that's exactly what I needed.

Probably echoing what’s been said above but:
You’re using something like the Victorian 712 battery monitor and you need to wire the shunt?
All negative wires go to one side of the shunt and the other side of the shunt goes to (house)battery negative. In your diagram above you have more than one ground going to your house negative, this is incorrect because those loads will not be measured by the battery monitor. This will make your battery monitor’s percentage readout incorrect.
Also since you are monitoring the house battery I would only ground to the shunt systems that draw off of the house battery, so not the off road lights etc that go to the truck battery.
Thanks for that info. The lights currently run off the truck battery, no issues there.

You should only have negative wires going to your shunt, and a temp sensor wire if you’re using one.
Thank you,

Why is your heater and muffler placed up so high? I'd rethink that and place it on the floor. That muffler will get hot and should be outside.

Sent from my Pixel 4a using Tapatalk
I appreciate the input but this is a topper" camper. The heater is mounted so that the entire camper w/ heater can be removed in a matter of minutes. I'm not particularly keen to cut a hole in the bed of my truck when this works perfect. I've run the heater all night on several occasions and have no issues with anything getting to hot or burning. The exhaust has less then a 12" run.



For clarity, one side of the shunt connects to the battery. All other negative connections including chassis ground go to the other side of the shunt. The battery's connection to the chassis ( if you need it) goes through the shunt.
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Perfect answer, thank you so much.


Sorry for the delayed response here. Thank you all for the immediate replies.
I've cleaned up the diagram. Any other blatant errors, please feel free to point them out.

 
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