Incorrect Shunt Connection?

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coltarkdm asked Feb 28, '20

Incorrect Shunt Connection?

It is very clear that there should only be one connection from the negative battery terminal to the supply side of the shunt. That said, the installation diagram for my Victron Multiplus 3000/70/24 indicates that the T-Sense cable should be run from the negative battery terminal to the T-Sense input on the Multiplus and that is how I wired it. Now I'm thinking that is incorrect and that the cable should be connected to the load side of the shunt. Ever since I completed my solar install, I haven't felt like my BMV712 has been displaying correct SOC and I'm hoping this change might help. What do you think? I have 4-100ah Battle Born in 24v configuration..

BMV Battery Monitor

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Answer 1 · 2020-02-28T16:55:49Z

Stefanie (Victron Energy Staff) answered · Feb 28, 2020 at 04:55 PM

No. It's correct the way you wired. The T-Sense has nothing to do with SoC.

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coltarkdm commented · Feb 28, 2020 at 09:33 PM

Thank you Stefanie!

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Answer 2 · 2020-02-28T20:06:58Z

Daniël Boekel (Victron Energy Staff) answered · Feb 28, 2020 at 08:06 PM

Hi @ColtarKDM

What are the settings in you BMV? (peukert factor and charge efficiency)

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coltarkdm commented · Feb 28, 2020 at 09:32 PM

Thanks for helping me. Here are my settings.

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Daniël Boekel (Victron Energy Staff) ♦♦ coltarkdm commented · Feb 28, 2020 at 11:05 PM

ok, and in what way is the SOC incorrect? is it too high or too low? or does it reset to soon?

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coltarkdm Daniël Boekel (Victron Energy Staff) ♦♦ commented · Feb 28, 2020 at 11:49 PM

Do my settings look good?

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Daniël Boekel (Victron Energy Staff) ♦♦ coltarkdm commented · Feb 29, 2020 at 01:01 AM

in what way is the SOC incorrect? is it too high or too low? or does it reset to soon?

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coltarkdm Daniël Boekel (Victron Energy Staff) ♦♦ commented · Feb 29, 2020 at 10:02 PM

SOC has a tendency to read low compared to actual voltage. I use the following chart as a guide.

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Daniël Boekel (Victron Energy Staff) ♦♦ coltarkdm commented · Feb 29, 2020 at 10:28 PM

That table is probably a guide, but actual voltage vs SOC will depend on a lot of things, like load / charge, temperature.

The only way to know if the SOC is correct, is to do a full charge, followed by a full discharge, and see how many Ah came out of the battery when empty.

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coltarkdm Daniël Boekel (Victron Energy Staff) ♦♦ commented · Mar 02, 2020 at 04:01 PM

What is considered a "full discharge" of my 4 Battle Born batteries at 24v and what is the best way to accomplish it? And finally, what do I do with that data?

TIA. Khris

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