Victron Smart Shunt Battery Settings - clarification of "Charged voltage"

[billymac]

I'm a little confused by the terminology, so please bare with me. Install includes MP2, Lynx, Smart Shunt, Cerbo, 150/85, 100/30 and 2x12V 560Ah LiTime batteries.

I'm trying to ensure my settings are optimal and accurate for my battery. From a terminology perspective Victron's "Charged voltage" is where I'm getting confused. What value should Victron Smart Shunt "Charged voltage" be?

Current connected youtube video recommends this value be 14V for LifePO4. I'm getting confused by watching Youtube videos and comparing to the Li Time battery manual. I'm also getting what I believe to be somewhat conflicting information from their support, but I think they're confusing "Charged voltage" with "charging voltage" possibly.

The first page of the LiTime battery manual states:
PRODUCT OVERVIEW
12.8V 560Ah Battery
Operating Voltage 12.8V
Charging Voltage 14.4 +/- 0.2V
Recommended Current 112A (0.2C)

On another page for Battery Charger Settings it states:
Recommended charging voltage between 14.2-14.6V
Recommended charging current 112A (approximately 5 hours to 100%)

On another page under solar "Controller Settings" it states:
Charge/Bulk/Boost Voltage = 14.4V +/- 0.2V
Absorption Voltage = 14.4V
Over Voltage Disconnect 15V
Over Voltage Reconnect 14.2V
Tail Current 11.2A (0.02C)

When I reached out to LiTime the first time, I asked them about absorption and float voltages. Their customer support person indicated I use 14.4V for absorption and 13.8V for float. There is no listing in the manual.

Can anybody help me clarify the terminology in smart shunt settings so that I can set them properly based on the above?

Thank you!

 

[Q-Dog]

I would use the Victron built in "Smart Lithium" charge settings for the charge parameters on the charge controllers and the MP. This sets absorption at 14.2 volts.

Set the "charged voltage" setting on the shunt to .2 volt under the absorption voltage, so 14 volts if you use the "Smart Lithium" charge settings.

 

[billymac]

I would use the Victron built in "Smart Lithium" charge settings for the charge parameters on the charge controllers and the MP. This sets absorption at 14.2 volts.

Set the "charged voltage" setting on the shunt to .2 volt under the absorption voltage, so 14 volts if you use the "Smart Lithium" charge settings.

Thanks Q-Dog. So that would mean 14.4 charging voltage, 14.2V absorption and 14V "Charged voltage", but what about float voltage? Li Time is telling me 13.8V, but Victron's manual for shunt states:

"The "charged voltage" parameter should be set to 0.2V or 0.3V below the float voltage of the charger.

*scratches head*

 

[Q-Dog]

Just use the "Smart Lithium" preset and it will populate the correct parameters.

 

[mikefitz]

Charge/Bulk/Boost Voltage = 14.4V +/- 0.2V

This is the charge voltage 'target'. Although li time support recommended 14.4 absorbtion, 13.8 float, these voltages are too high, especially the float voltage. The terminology is confusing, charge, boost, bulk, absorbtion voltage, are all the same thing, a voltage target the charger is aiming th reach durring the main period of charge. Once the target voltage is reached , there is an absorbtion period, ( boost duration) where the charge is 'topped off'. The absorbtion voltage are held constant during this period. Once the absorbtion period is completed the charger drops the voltage to float level.

The "charged voltage" parameter should be set to 0.2V or 0.3V below the float voltage of the charger

The smart shunt syncs to 100% when this voltage, 'charged voltage' is exceeded, along with tail current below a threshold. This works as suggested in the Victron notes if a powerful charger is allowed to complete a full charge cycle
A more reliable 'charged voltage' value is just below the 'target voltage', the absorbtion voltage, reached by the charger. Use the Victron default absorbtion charge voltage, 14.2volts, and set 14.0 volts as the 'charged voltage' in the shunt.

about float voltage? Li Time is telling me 13.8V, but Victron's manual for shunt states:
"The "charged voltage" parameter should be set to 0.2V or 0.3V below the float voltage of the charger.

Charged voltage perameter is a 'test condition' used by the shunt and in no way effects the charge process.

 

[billymac]

This is the charge voltage 'target'. Although li time support recommended 14.4 absorbtion, 13.8 float, these voltages are too high, especially the float voltage. The terminology is confusing, charge, boost, bulk, absorbtion voltage, are all the same thing, a voltage target the charger is aiming th reach durring the main period of charge. Once the target voltage is reached , there is an absorbtion period, ( boost duration) where the charge is 'topped off'. The absorbtion voltage are held constant during this period. Once the absorbtion period is completed the charger drops the voltage to float level.

The smart shunt syncs to 100% when this voltage, 'charged voltage' is exceeded, along with tail current below a threshold. This works as suggested in the Victron notes if a powerful charger is allowed to complete a full charge cycle
A more reliable 'charged voltage' value is just below the 'target voltage', the absorbtion voltage, reached by the charger. Use the Victron default absorbtion charge voltage, 14.2volts, and set 14.0 volts as the 'charged voltage' in the shunt.

Charged voltage perameter is a 'test condition' used by the shunt and in no way effects the charge process.

Thanks Mike, I really appreciate. I'll make these corrections next time I'm out to the rig. Both of my Victron SCC's are set to 14.2V absorption / 13.50V float. Assuming no issues there? All I need to do is double-check the "charged voltage" in shunt battery settings is set to 14V.

Assuming similar setting in MP2 settings tab that need to ensure line up as well.

I turned off the master switch last week after doing a partial charge cycle with my generator, so I don't have remote access at the moment, but I'm headed out there later this week and will run through everything again.

Regarding Q-dogs point about simply setting the "smart lithium" template setting, I thought there was something manual that a lot of folks change that take you into "expert" territory. I just can't recall without seeing the menus though.

/edit -- now I remember. I was going into "expert mode" on the SCC's battery settings to extend absorb to 2 hours to help balance cells. I need to go back and lower those values to 30 or 60 minutes.

One more questions: what do most people use for "charged detection time" on the shunt? Do they stick with 3 minutes?

 

[740GLE]

The biggest thing to be aware of is the fact these li time units need balancing time, otherwise the packs will become unbalanced and you might hit cell over voltage disconnect and never be able to hit 14.2v without a BMS turning off.

Because you can’t monitor each cell voltage, you just have to dial in the charging parameters to allow balancing to happen, and then make sure each month they have enough balance time to keep them happy.

 

[mikefitz]

. I was going into "expert mode" on the SCC's battery settings to extend absorb to 2 hours to help balance cells.

If there is a problem with unbalanced cells, ( indicated be a sudden drop of charge current to zero towards the end of the charge cycle) , then it may be a more ideal situation to set absorbtion and float to 13.8 volts and run with these settings for a few days.

most people use for "charged detection time" on the shunt? Do they stick with 3 minutes?

I guess most use the default settings.