SBMS0 Control over MPPT Charge State vs.. SBMS0 Control over Victron Quattro Charge State

[Dustin Dudley]

Even though they should function the same, these appear to be completely different. When the SBMS0 says “stop charging” via CFET, the MPPT simply stops. So does the Quattro (assuming a generator is providing power to the Quattro). Then when the CFET is cleared (SBMS0 is saying “resume charging”). The MPPT’s simply resume providing all the power that they can provide given the available PV. This is where things get weird. The same CFET is cleared (SBMS0 is saying “resume charging”) command is treated completely differently by the Quattro. It appears that defeating all of the “helpful” charging algorithms within the Quattro is not so simple. There appears to be a power struggle (no pun intended) between the simple “on” “off” provided by the SBMS0 and the proprietary charging algorithms that the Victron Quattro insists upon to be “helpful.” However, for my use case scenario it is far from “helpful.”

 I may have things misconfigured within the Victron Quattro. It appears that there are 3 different ways to add an “Assistant” to the Quattro. One is under the “All assistants” tab. 

Another is under the “Auxiliary input” tab. 

And yet another is under the “Lithing (non Hub system)” tab. 

Then, for configuration of each one has choices to make such as: the number of contacts for high-cell/batter full and low-cell conditions (among the choices I think I have this set correctly). 

Then I choose “the battery is full when “Auxiliary input 1 is open” and “the battery is empty when “Temperature sense input is open”, which also seems correct. 

But then the Quattro Assistant setup gives a weird choice. “Specify the action to perform depending on high-cell/battery full.” You have to choose between “Force to float” or “Disable charger”. 

If you choose “Force to float” the system works (kind-of). If you choose “Disable Charger” the Quattro goes into “Passthrough Mode” and allows the generator to carry existing loads but will NEVER turn on the charger. If you choose “Force to float” the charger provides lots of Watts when the batter is very low, but then barely provides anything as the batter gets over about 80%. This is maddening because I want the SBMS0 to be in complete control like it is with the MPPT’s. CFET should be an absolute. Like telling the Quattro to charge with all of its might or to simply stop charging. But it is not working that way.

 If anyone can shed some light on this, I would be forever in your debt. I have attached pictures of the Victron Quattro programming/configuring pages I am referring to for reference.

[sailingharry]

Just guessing, but a guess worth investigating.

I think (but you've caught up with me and I'm "leading from behind") that this is what is happening.

If you use "drop to float" then the SBMS0 apparently doesn't stop charging, just "drops to float."  And in that mode, it won't charge much (or at all).  This isn't ideal, as the SMBS0 should stop ALL charging.  In this mode, I don't see a way for it to ever resume absorption.  Weird, but that's how I read it.

Worse is "disable charger."  This is what  you WANT it to do -- but I don't think it re-enables until you hit the Type 2 (right?), which tells the inverter you have an empty battery and can resume charging.

It seems that, despite initial thoughts, 2-signal BMS is a bit of a mess. Type 1 should turn Absorption on/off, Type 2 should turn inverter on/off.  That's all, that simple. 

[Dacian Todea (electrodacus)]

You need to chose “Disable charger”.

Not sure why you say it never turns ON the charger. I do not think Quattro will work different from Multiplus and so charging should resume when SBMS0 asks for that. You may have set up the max SOC and not realize that SOC needs to drop 3% below your set limit for the charging to resume is no longer based on CFET flag in that case. Only if max SOC is set to 99% the CFET flag will dictate when charging will start.