help with cerbo gx

[btempini]

Hey yall, I just finished setting up my electrical system and I am getting some weird readings on my cerbo gx. The DC Power is showing negative wattage and is flowing back into battery? How is this possible? Im going to attach my wiring diagram and an image that shows what I'm talking about, I have a DC-DC charger but its not hooked up yet, and its night time (as you can see pv charger at 0, and I'm not plugged into shore power so there are no other charging sources, which makes me think I may have wired up the shunt wrong? Any help would be greatly appreciated.

 

[sunshine_eggo]

Your battery power indicator should be negative:



From the manual:

https://www.victronenergy.com/upload/documents/Lynx_Shunt_VE.Can/24534-Lynx_Shunt_VE_Can_Manual-pdf-en.pdf

11.3.1. Charge and discharge current are inverted

The charge current should be shown as a positive value. For example: 1.45A.The discharge current should be shown as a negative value. For example: -1.45A.If the charge and discharge currents are reversed, the negative power cables on the battery monitor must be swapped.

 

[btempini]

first off, thanks for your reply! i just checked that in the manual, and all it really does is confirm my concern. Negative power cables? that's confusing, when they say battery monitor they mean the shunt right? I might need this dummed down a bit for me lol. Am I supposed to swap the positive and negative on my shunt?

 

[btempini]

ahhhhhh wait, i just had a moment

 

[btempini]

okay so this must be where I went wrong, Im assuming I have these installed incorrectly.

 

[sunshine_eggo]

The shunt measures a voltage drop across the resistor. If the sense wires are backwards, the current is inverted.

 

[btempini]

im still confused, it looks to me as though everything is hooked up correctly, the +/- from the cerbo are wired to +/- on the distributor, respectively. Maybe im just not understanding terminology, i understand what a shunt does, but what are the sensor wires your refering to?

 

[Rocketman]

Ok I see your issue…
Yes it is wired up “backwards”.

The way it’s supposed to be wired up from left to right is: PowerIn (connected to batteries), Lynx shunt, Distributor with all the loads. (Section 3.1 in the manual).

Your setup is: Distributor with loads, Lynx Shunt, Cables with batteries.

To fix - swap the distributor and shunt locations so the setup goes from right to left as Victron designed. Can you just move the shunt to the left side of the distributor?

 

[btempini]

ohhh I did not realize it was designed to go in one direction, that's annoying. seems like it shouldn't matter tho, power still goes in at the shunt, and out at the distributor. I am still learning after all, so this is going to be a costly mistake, mainly because I need a bunch more 2/0 now. thanks for your help!

 

[Rocketman]

Another option is to turn everything upside down - then it will be in the right direction - and you probably don’t need new cables.

 

[btempini]

Meh its okay im gonna do it right, I shoulda read the manual from the beginning. lesson learned...

 

[btempini]

hopefully i didnt damage anything

 

[Rocketman]

In the manual turning it upside down is an option - the manual says they give you stickers for just that reason.