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Dave Dickhoff avatar image
Dave Dickhoff asked

Smartshunt SOC readings

Problem: SOC jumps from 95% to 100% when charging with the Smartsolar MPPT 100/30, I asume it is because it meets the conditions of "voltage as charged"
System:
- Multiplus II 24/3000
- SmartShunt 500A/50mv
- Smart solar MPPT 100/30
- Cerbo GX
- Battery balancer
- Battery bank center point monitoring
- 690A AGM 24V battery bank

After watching the video by Johannes regarding the correct set up of a BMV monitor, I am not sure of my case and I have 2 questions for this community:
- What values should I enter in the SmartShunt to solve this problem:
Charging voltage setting(VC)
Tail current setting
Further settings
- Does this not affect the SOC measurement if I charge with the Multiplus II.

Thank you very much in advance for your help

smartshunt-settings.png

SmartShunt
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6 Answers
derrick thomas avatar image
derrick thomas answered ·

Post a screenshot of your settings in the smart shunt

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Dave Dickhoff avatar image
Dave Dickhoff answered ·

Sorry, done

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derrick thomas avatar image
derrick thomas answered ·

Charged voltage should be about .2 volts below the absorption voltage setting. With your low setting and low output of mppt you will get false SOC synchronization.

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Dave Dickhoff avatar image
Dave Dickhoff answered ·

Hi Derrick, thnx for the quick reply, can you please tel me what in my systems the absortion voltage is?

And this will not be affect the SOC when I charge with te Multiplus?


Many thnx,


Dave

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derrick thomas avatar image derrick thomas commented ·
Your battery manufacturer should have charging specifications for your batteries. Bulk/absorption and float voltages should be set in the multi as well as the mppt. All AGM's vary slightly but your absorption should at least be somewhere north of 14.2 volts possibly as high as 14.8, but again, your manufacturer should provide this information.
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seb71 avatar image
seb71 answered ·

what in my systems the absortion voltage is

This is set both in MPPT and in MultiPlus. Should be the same value in both.


A SOC synchronization from 95% to 100% it's not such a big deal, especially if your battery did not reach 100% for a few days before that.


I asume it is because it meets the conditions of "voltage as charged"

Not just that. There are 3 SmartShunt/BMV parameters which control the SOC synchronization:

  • charged voltage (if you decrease this, the synchronization will happen sooner);
  • tail current (if you increase this, the synchronization will happen sooner);
  • charged detection time (if you decrease this, the synchronization will happen sooner).

By observing your system for a few days/weeks, you adjust these 3 values until you get the optimal situation. Will never be perfect, because values which are good for sunny days are not the best for cloudy days and viceversa.


This is all explained in the manual and in that video you mentioned.


Also, make sure that SmartShunt is set as the battery monitoring device in your Cerbo GX.

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Dave Dickhoff avatar image
Dave Dickhoff answered ·

Great, you guys help me a lot with this.


thnx,


Dave

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