Victron shunt drift ?

[Kcdaniels]

yep -- that's why. SCC Absorb is 14.02 .. less than the shunt's 14.2 ... so I'd set the shunt to 13.9

Thanks I change that and comeback in a few days with update?

 

[740GLE]

Set them to the same, you have a VE.Smart network between the SCCs and the Shunt?

 

[Kcdaniels]

Set them to the same, you have a VE.Smart network between the SCCs and the Shunt?

Yes

 

[cinergi]

I disagree on setting the shunt's Charged Voltage to the same as Absorb. Set it 0.1 volts lower. Why?
1) https://www.victronenergy.com/upload/documents/SmartShunt/9172-Manual_BMV_and_SmartShunt-pdf-en.pdf -- this actually recommends setting it to 0.2 to 0.3 volts lower than float but that's probably more reasonable for lead acid. Additionally:

The battery voltage must be above this voltage level to consider the battery as fully charged. As soon as the battery monitor detects that the voltage of the battery has reached this “charged voltage” parameter and the current has dropped below the “tail current [23]” parameter for a certain amount of time, the battery monitor will set the state of charge to 100%.

(bolding is mine)

2) It's been my experience that the shunt often sees slight dips in observed voltage versus what the absorb voltage actually is. e.g. if absorb is 14, the shunt might see 14v 80% of the time but occasionally sees 13.9 volts. Any dip in a 3 minute period will reset the timer for considering the battery charged. That's why I (and the documentation) recommends setting it LOWER. With LiFePO4, as long as that voltage is inside the charging curve "knee", you'll be OK.

Will setting it to the same value work for some people/situations? Probably; but the most robust setting is 0.1 volts lower than absorb (as long as that's within the LFP knee).

 

[Samsonite801]

Set them to the same, you have a VE.Smart network between the SCCs and the Shunt?

I'm assuming you're meaning to say here maybe, is that if you have multiple Victron SCC's, to set them up in a network group on the shunt, and set all the SCC's to the same charging voltages (absorption and float), and then set the Charged Voltage slightly lower as discussed.

I do this, using the Bluetooth network, created a network group, add the shunt and the SCC's to that group, absorption on the SCC's both set to 14.08v, while my BMV shunt Charged Voltage is set to 13.9v, set float on the SCC's to 13.4v, works great.

 

[sunshine_eggo]

I disagree on setting the shunt's Charged Voltage to the same as Absorb. Set it 0.1 volts lower. Why?
1) https://www.victronenergy.com/upload/documents/SmartShunt/9172-Manual_BMV_and_SmartShunt-pdf-en.pdf -- this actually recommends setting it to 0.2 to 0.3 volts lower than float but that's probably more reasonable for lead acid. Additionally:

(bolding is mine)

2) It's been my experience that the shunt often sees slight dips in observed voltage versus what the absorb voltage actually is. e.g. if absorb is 14, the shunt might see 14v 80% of the time but occasionally sees 13.9 volts. Any dip in a 3 minute period will reset the timer for considering the battery charged. That's why I (and the documentation) recommends setting it LOWER. With LiFePO4, as long as that voltage is inside the charging curve "knee", you'll be OK.

Will setting it to the same value work for some people/situations? Probably; but the most robust setting is 0.1 volts lower than absorb (as long as that's within the LFP knee).

Along those lines, the manual addresses sync issues associated with setting charged voltage based on float:


It's not mentioned in the config section. One has to go to Troubleshooting.

 

[Kcdaniels]

Well the settings seem to have brought the shunt more in line now ?
Normally every other day it was showing around 94% at 13.75... Now showing 100% at 13.75?
Thank you to all that helped ! Hope this thread helps someone else down the road.