I have two different Victron MPPT Smartsolar chargers on a boat set for charging 520AHr AGM batteries using charge profile 2 - 14.4V boost and 13.6v float. When I look at the battery voltage as reported by a Smartshunt, the boost is attaining 14.2 before dropping to 13.4 float. I have plenty thick cables and short runs so I don’t think V.drop is an issue. Which do I believe? I don’t want to increase the Smartsolar voltages by 0.2v and risk overcharging, but by the same token I don’t want to undercharge them either. The quiescent draw on the system is around 14 watts - (wifi, cctv and cerbo) even when I’m not there so the batteries do cycle a bit daily, more so in winter. DO I use a 3rd party calibrated multimeter, or trust one of these readings? If so, which?
Definitely get the verification of a meter.
Method -No charging present.
Actual terminal voltage
Shunt voltage
Mppt terminal voltage
If you look at your agm specs there is an allowance of up to 0.3v. (sometimes 0.5v) charge voltage.
For AGM is matters more actually to not overcharge as in put in too many amps and get hot (they dry out)
Or hold them up at the high voltage for too long.
Are you using V.E smart networking?
It allows comparable devices to wirelessly share battery voltage, temperature, and current data, enabling synchronized charging to optimize battery health and charging efficiency.
My system uses it and compensates for any variance in voltages.
As it happens I used to use it, but in the victron manuals it says that this is generally intended for systems without a cerbo and when you do have one you should disable it. I disabled it some time ago. I wonder which it would choose to be the master voltmeter in that instance?
I believe it uses the shunt voltage as the master, I run an RPi with VRM so close to a cerbo, I hadn’t seen that warning but will continue as I am.
Having googled it and read some more I read that I was correct to disable the network, but instead, to enable DVCC which then does the dame thing but over the VE Direct cable network and the Cerbo controls everything whilst using the smart shunt as the Voltage reference. If just done that and will see how it looks over the coming days. Thanks for your posts. They pointed me in a direction that hopefully led to answers.
You didn’t mention a cerbo in the post. But good to know.
Definitely, you don’t mix the cerbo and smart network. The cerbo is the network engineer.
If the shunt is set as the system battery monitor on the shunt, everything will be referring to that.
Actually, I did mention that the cerbo was part of my quiescent loads but I can see how you may have missed it being networked to the shunt and smartsolar controllers via ve-direct. As far as I can see you don’t get the option to tell the cerbo that the shunt is the reference. It must select it automatically if you have one. Makes sense to use it since it’s meant to be the closest device to the battery..
Selective blindness. Apologies.
In DVCC use SVS
Summary
The system automatically selects the optimal voltage measurement. If available, it prioritises the voltage from the BMS or a BMV battery monitor. If neither is accessible, it defaults to the battery voltage reported by the VE.Bus system. The voltage displayed on the GUI corresponds to the selected voltage measurement.