Can not get the smartshunt to autosyncronise

[syorigami (Tansel)]

Hi there,

First the system summary (on a 38ft boat):

• 2x225Ah (new) Mastervolt AGM batteries in parallel as service bank
• 2x340W solar panels in parallel
• Victron SmartShunt 500/50
• Victron SmartBatterySense
• Victron MPPT 100/50 only charging service bank
• Three victron items above are networked and communicating properly
• Victron phoenix smart 3000VA inverter (switch operated, mostly in off state)
• Shunt installation is correct: single cable from battery terminal to shunt
• Cables are properly sized: 70mm²

The parameters on devices:

MPPT (made as preset for the batteries)

• Absorbtion voltage is 14.25V as Mastervolt specified marked on the batteries and documents
• Float voltage is 13.8V as Mastervolt specified marked on the batteries and documents
• Temperature compensation is -30mV/°C as Mastervolt specified marked on the batteries and documents
• Equalization disabled
• Re-bulk voltage offset: 0.40V
• Absorbtion duration: Adaptive
• Max. absorbtion time: 5hrs
• Tail current: 9A

SmartShunt

• Battery Capacity: 450Ah
• Charged voltage: 13.8V (also tried 13.6V and 14.0V in efforts to get autosync working, but didn’t)
• Discharge floor: 50%
• Tail current: 2%
• Charged detection time: 3m
• Peukert exponent: 1.11
• Charge efficiency factor: 96%
• Current treshold: 0.10A
• Time-to-go averaging periond: 3m
• Just after install, zero current calibration was done.

The voltage readings from all victron componentes as well as boat’s control panel are consistent all the time. Since I am in the Aegean region, around noon time everyday I get the SOC 100% and float state everyday. My nightly loads are minimal and since batteries are new I read around 12.7-12.8V in the mornings with SOC bwtween 92%-95%.

However, autosync count on shunt is at 0 (zero) for almost 10 days after the installation despite I have observed on shunt screen in app that three conditions for autosync are met several times. (voltage/tailcurrent/time).

Where am I doing wrong?

Thanks in advance for your comments and suggestions.

[pwfarnell]

Two thoughts which I have seen before.

1. Your MPPT is going to float before the synchronisation so the battery current goes negative before the 3 minutes are up. The SmartShunt stops counting as charge has stopped. The battery current has to be below tail current AND above 0 for the 3 minutes. Either make sure your MPPT tail current is lower than 2% or the absorption time is long enough or try 4% on the SmartShunt.
2. The SmartShunt is counting back up to 100% before it gets to the auto synchronisation, hence it does not count as an auto synchronisation.

Your SmartShunt settings seem OK.

More info in the following link although this is not your issue

Battery monitor jumping to 100% or reporting a high SOC with low Volts / the BMS shuts down

This topic covers the reported SOC being out of sync with the actual battery voltage or state. It covers BMV battery monitors, SmartShunts, Lynx BMSs and Lynx Shunts and will just be called shunt below. It is also assumed that the shunt is monitoring the domestic / house / cabin battery bank and not engine start / bow thruster / winch / caravan mover battery banks. The problems may be one or more of the following and is often linked to mobile applications with small solar systems. The SOC jum…

[syorigami (Tansel)]

Thanks, I will try your suggestions.