SoC not updating data upon alternator chargin

Q&A and troubleshooting
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Hello. Thanks in advance for helping.
I’m posting this because none of the post i’ve read fixed my problem.

PROBLEM:
My victron shunt BMV-712 is not updating the data neither while and later on using the car’s alternator.
I checked the topics but maybe I need another solution.
Here is my simplified setup: https://drive.google.com/file/d/1o-0IAXUDoeU4vAkTOjll1jN3tcdokwlJ/view?usp=sharing

FIXING I TRIED:

  • i tried to disconnect the service battery from the car chassis. What happened is that neither the BMV was updating the infos nor the battery was charging anymore. I found out i need 100% the service battery to be connected to the chassis in order to charge the battery with the alternator.

NB:

  • I understand that maybe a possible solution would be to create a connection between the NEGATIVE alternator to the NEGATIVE of the loads, but I dont want to do it. I have a Volkwagen T5 and it was a mess to work my cables through the car and now I would like to work with what I actually have.
  • I dont remember if my starter battery is connected to the chassis. If you guys need to know this information i can look it up.
    Can anyone help? Am I missing something?

I really with to not make any more reduntant posts, but I cant get why i could not find the solution to my problem.
I think i made all the wiring perfectly, but im ready to fix in order to some advices :slight_smile:
Thanks in advance,
Edo

2

Simple one seen often, answered in the FAQs in the sticky post at the top of the DIY section. Your chassis connection to the service battery needs to go to the system side of the shunt. The alternator charges through the chassis so it bypasses the shunt.

1 Like
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Damn! <3
Thanks Sir for taking time to answer back.
Today I’m gonna work on it.
I’ve never seen this well explained. Around they just say this “ONLY 1 CABLE FROM SHUNT TO BATTERY NEGATIVE”……….
But I also would like to understand, so correct me if i’m wrong.

The alternator is ACTUALLY connected to che chassis so it is as well connected to my service battery and this is why the charging is working.
To make the shunt READ the flow I connect the CHASSIS to the SHUNT so that the NEGATIVE FLOW of the alternator HAS TO GO to the shunt before the NEGATIVE OF THE BATTERY. Am I correct?

1 Like
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Yes, you are correct, chassis connected to the system side of the shunt.

5

Hello again.
I made the changes you suggested.
I WIRED THE CHASSIS to the “LOAD AND CHARGER” of the shunt. Makes a lot of sense, now.
Now the shunt registers a 15A in positive of charging, more or less 200W while the car engine is working with the car standing still.

I’m very thankful. I don’t think I am a stupid DIYer and I do my best, but SIR you are the first one pointing this out.
Thanks for taking the time. I get frustrated with redirected to FAQs.
Definetely deserve a beer or 2 from VICTRON.
Have a good life sir pwfarnell.
Edo

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