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Need help wiring DC-DC charger and battery monitor

GratitudeJourney

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Feb 17, 2022
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I installed 2 100ah SOK batteries in my motorhome and also changed the converter to a WFCO 8955 lithium w/ auto detect. That was a fairly simple install because I just had to disconnect and reconnect the same wiring. Now I have a Renogy DC-DC battery charger with MPPT, (hope to be adding solar at some point) to protect my alternator and a Renogy 500A battery monitor to install and I am a bit overwhelmed. I don't know why, but the shunt part is throwing me off. I was hoping someone might be willing to walk me through the wiring of these two. I'm happy to venmo or zelle someone some cash for their time. Thanks in advance
 

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The shunt must be the only thing connected to the battery (-), either directly or via a single battery cable. All chargers and loads, including any grounding connection, should be connected to the other side of the shunt.

Graphically:

1650906955388.png

Shunt indicated by arrow
 
Last edited:
The shunt must be the only thing connected to the battery (-), either directly or via a single battery cable. All chargers and loads, including any grounding connection, should be connected to the other side of the shunt.

Graphically:

View attachment 92555

Shunt indicated by arrow
Thank you for taking the time to reply! So the way it is currently wired, the negative side of the battery is grounded to the chassis and then wired in parallel to the other battery negative. Would I disconnect the grounded wire from the battery and wire it and the common negative from the DC-DC charger to the P- side of the shunt? Then connect a wire from the B- side of the shunt to the battery and leave the wire between the two negative sides of both batteries?
 
It's critical that all current that goes to/from the battery passes through the shunt. Since you're basically using the vehicle ground as a giant bus bar, it must go between the battery and ground.

The shunt keeps track of the NET current in and out of the battery. if you're charging with 10A, but you're using 5A, the shunt will only see that 5A is going to the battery. If you bypass the shunt, it's SoC will be inaccurate.
 
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