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What parameters/settings for 2 SOK 206Ah batteries and Victron SmartShunt 500A/50mV?

FR Steve L

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Nov 27, 2022
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I recently upgraded my solar and battery setup and am wondering what some of these parameters on the Victron SmartShunt should be set to? I did some research to find the values that are currently populated (screenshot below), but want to get confirmation here if possible.

My question(s) is/are: (1) What should the settings/parameters be on the SmartShunt screen? (2) Are the values in the "Charge voltages" section of the SmartSolar screen correct?

Here are the components that I have:
1. Victron Multiplus 12/3000/120-50 120V Inverter
2. Victron SmartShunt 500A/50mV
3. Victron SmartSolar MPPT 100/50 Charge Controller
4. Victron Cerbo GX Touch 50 Display
5. Two (2) SOK 206Ah Lithium batteries (wired in parallel for 12V system, 412Ah total)

SmartShunt screen through VictronConnect app - "Settings" > "Battery"
316726964_879832653334319_1445618338341457397_n.jpg

SmartSolar screen through VictronConnect app - "Settings" > "Battery"
316739791_6484962831533847_5222502853958194842_n.jpg

SOK BMS screen through ABC-BMS app
317001228_517326936784531_8922107054645583298_n.jpg
 
This is info SOK Dealer gave out.... There is a debate about Charge Voltage and Absorption. They don't give time length of Absorption.

Explained:

Battery Capacity: 206a

This is calculated by adding up the amp-hour (Ah) rating of all PARALLEL strings. For example 2x 100ah batteries in parallel would be 200ah. Series batteries add voltage together; amp-hour capacities do not add together in series.

Charged Voltage: 13.8
This is DIFFERENT than the absorption / charging voltage! It is the voltage at which the shunt considers the battery close enough to fully charged to start detecting a current drop (the current drop indicating a true full charge).

Victron’s recommendation is setting charged voltage .2v below absorption voltage – while perfect for most lead-acid batteries with a long absorption period, it’s not perfect for the SOK Lithium batteries.

The problem is, in order for the shunt to synchronize to 100%, the batteries must be above this voltage, and while above this voltage, the current must drop below the tail current threshold.

If this voltage is set too high, then it will never start monitoring for the current to drop meaning it never catches the condition that means the batteries have truly reached 100% state of charge.

Tail Current: 2.00%
After the previously mentioned “charged voltage” has been reached, this is how much the current must taper down to trigger a synchronization. Our testing has proven the default value from Victron is sufficient for proper detection.

Charged Detection Time: 3m
Also working in conjunction with “charged voltage” and “tail current”, once the tail current has reached the appropriate set-point, it waits this amount of time to make sure the current drop isn’t just momentary and that it is truly occurring because the battery is full.

Peukert Exponent & Charge Efficiency Factor: 1.05
These are fixed values driven by characteristics of the battery itself. No tweaking or adjusting needed here.

Charge Efficiency Factor: 98%

Current Threshold: 0.10a

The minimum amount of current the shunt can detect. This does not pertain to the battery itself.

Time to go averaging period: 3m
How often the time-to-go readout is recalculated and update. This also has no effect on the battery itself.

Discharge Floor: 10%
This is for you to adjust. Let’s say you setting this at 10%; when you get to 10%, the Smartshunt will indicate 10% remaining and 0 minutes until empty on the “time to go” reading. If you choose to know how long until you have fully discharge your battery instead, then set this to 0%. If you want to be more conservative on your time remaining, then set this to 20% or higher.

Battery Starts Synchronized: Disabled
This only applies to the SmartShunt and BMV-712. If this setting is enabled, then every time the shunt looses power, it will set the SOC% to 100% at power up, instead of saving where it was previously at. This could cause confusion if turned on.

Let’s say you are draining your batteries and reached 0% remaining and the BMS cuts off. When you start recharging, the shunt will show 100% immediately, since the shunt lost power and changed the SOC% to 100%. Obviously a totally empty battery just put on the charger wouldn’t be at 100%!

State of Charge: Not Changeable?
This is a manual override to set the SOC%. If you just got your batteries, then they ship from the factory at approximately 30% charge, per DOT regulations.

You could then manually set 30% so your shunt is close to accurate on the first charge. Similarly, if the batteries shut down on over-discharge, and the shunt lost it’s place, then you could also set this to 0% so you could have an idea of how much the batteries have charged.
 
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