I have a complete Victron system on my boat. It consists of 3 x 360w LG panels each going to a separate Victron 100/30 MPPT. I have an additional 3 custom marine panels totalling 525w each going to a separate Victron 100/20 MPPT. There are no loads on the MPPTs. They go to the batteries (3 x 300Ah Relion rb300) and between the batteries and house loads is a smart Shunt. Lynx Power In bus bars are installed for the Mppts and batteries.
The problem is that the Smart Shunt is never able to reset to 100% SoC because once the charged voltage occurs (13.8v) the MPPTs throttle down the solar rather than continuing to power the loads. In other words, once 13.8v is reached, the batteries start discharging at about -20A. The MPPTs show they are in absorption and continue to rise to 14.2v. Eventually they change to float. This happens every day. Previously had the charged voltage set to 14.2v, but same thing happened (throttled down solar). Left the charger voltage at 13.8v as recommended by an expert. I’m currently in The Bahamas and get full sun nearly everyday. Panels are clean and without shading.
I’ve taken reading at the MPPTs battery terminals and they are congruent with what I see on Victron Connect (+/- 0.02 volts). The current readings from MPPTs towards the batteries are congruent. The current draw from the battery is also congruent, as is the voltage at the batteries.
I noticed today that MPPT 2 & 3 went into float mode while the rest remained in absorption.
I reviewed my MPPT, Smart Shunt and DVCC settings in another thread and they’re all good.
Not sure what’s going on, but it’s not allowing the system to operate to its full potential.
If you’re not using a GX device with a controlling BMS then create a a VE.Smart network and have all the MPPT controllers join that. That way they can synch their charging state.
See here ..
The system does have Cerbo GX in the network, which I forgot to mention.
A smart network was previously live, but an expert recommended disabling that network in favor of the GX/DVCC to avoid potential conflicts.
I would review the smart shunt settings. For your lithiums above float and a bit below absorption may work better.
And maybe your charge detection time or tail current settings as well if thet does not help.
Nothing is capped in dvcc? When they are with non can connected batteries, usually they follow their own internal programming.
Looking at the battery charge characteristics from the webpage your battery voltage curve looks correct.
There is not much capacity over 13.5-8 (you can tell by the sharp rise) so it is really done for balancing.
LX is correct, in that when there is no controlling BMS integration with your cerbo then each solar charge controller will effectively do it’s own thing. You didn’t say, but I assume your MPPTs are smartsolar charge controllers and all are connected to the Cerbo GX. But even in this scenario, without a controlling BMS they will follow their own configuration without synchronisation with each other.
Personally, in this situation, I would be creating a smart network, have all your devices that are capable of joining that smart network do so (MPPT’s, smartshunt, Orion’s), give each charging device the same charging characteristics (same absorb and float voltages, and this would include charging devices not in the smart network, such as a mains powered charger), enable DVCC with shared voltage and current sense and the smartshunt specified as your battery monitor.
Once that is set up and running and you can see that the MPPTs are operating in synch I would then look at the smartshunt settings and tailor those as needed.
I actually saw a similar situation with a friends van conversion. His installer had installed a Multiplus ii, Orion XS, 2 x Smartsolar MPPT controllers, a smartshunt and a Fogstar drift 628ah lifepo4 battery (whose BMS does not integrate into the Victron environment). What I was seeing was that one MPPT controller was consistently entering float whilst the other was in absorb. Creating a smart network, configuring each device to similar charge profiles (same voltage points), etc solved this isssue and it was then a case of checking his shunt settings (we changed the charged voltage, tail current and time to suit his battery characteristics).
Now, I’m not professing to be a Victron expert, the are many on here that are and may be able to help you further.
I told @Jseb that I was going to steer clear of this thread having been through a 37 page 2 week odyssey with him and not found a solution either with or without a VE Smart Network. However, today, I finally found that he has 2 30A Orion chargers from the house to starter batteries that kick in right at the end of the bulk phase of charging and add an extra 60+ Amp draw onto the lithium batteries just before they reach absorption voltage. A 60+ Amp draw is higher than the solar production, which is why the batteries start discharging as the solar can not cover this and as the batteries start discharging BEFORE the shunt reaches synchronisation settings it never synchronises.
I have added this here to stop additional time being spent on this question until he can investigate the new finding further.
That’ll do it.
He does mention a load here.
Obviously rebulk isn’t triggered by the load.
Thanks for the chime in. I wanted to look for the other thread but didn’t get time to.