At first I thought this was a Batrium issue:
However, when I set DVCC to 0A, it still allows up to 0.5A:
BMV-702 is the configured battery monitor.
MPPT charging is clearly being throttled, but it's allowing charge when it shouldn't.
I can set GX current limits at other times, and it doesn't go over, e.g., if I set to 30A, It will usually peak at 29.7A or something like that.
This is a concern for Lithium battery charging below freezing.
As a possibility, sometimes there is 'noise' from the system. See current threshold in manual. Although not normal to be 5A.
Have you checked with a meter to verify?
I have not verified with a separate tool, though I will. The batrium shunt reports the identical current, so I have at least two devices reporting this current. Additionally, over the last two hours, battery voltage has slowly crept up with essentially constant load, which supports the conclusion that there is a net inflow of current to the battery:
Thought of current threshold. Was set to 0.1. I changed it to 0.01A. Still outputting 0.5A with blips up to 0.6A now.
Confirmed with a meter that current is actually flowing to the battery. Clamp meter reads (+) in one direction and (-) when I flip it around.
Further confirmed battery voltage is increasing supporting the conclusion there is a net flow of charge into the battery:
0.1V rise with 0.4A (start) - 0.7A (end) input for a little over 4 hours.
Confirmed there are no loads between shunt(s) and battery.
Temporarily disconnected BMS and observed same behavior with GX DVCC set to 0A charging.
At this point, I can only conclude the GX is responsible for the "leakage."
Can this be fixed?
Setting BMV threshold to 1A forces it to read zero, but the Batrium shunt still shows the 0.4A value:
That is interesting and somethjng I have not seen on my systems. Will see about testing it out.
Does the battery send 0 CCL or any signals like that?
I don't know what 0 CCL means.
Here's more info:
Lifted low-temp charge restrictions. BMS is commanding 100A:
GX still set to 0A. Allowing 0.7A:
Set GX to 5A:
Hmmm... both shunts report > 5.0A by about the same amounts as when set to 0 - 0.5-0.7A offset.
Same for 20A:
I'll confirm the 0.5A "leakage" at 0A charging with a clamp meter when onsite tomorrow morning, but this is starting to look like the GX is allowing about 0.5A more than is specified in all conditions. My 30A comment was based purely on memory, and I may have been mistaken.
In the interim, I'm going to implement a safety that signals the MPPT to shut off completely as a secondary protection closer to freezing. I'm also seeing about 5-10°F variations between BMV, Quattro and BMS temp readings. The BMS temp sensors are directly attached to the cells with a piece of foam insulation on the exterior. The two victron sensors are literally right next to each other but reading about 5°F difference. If I had better correlation, I would feel more confident about charging near freezing.
I don't know what's going on, but this problem appears to have corrected itself. When the Batrium sends a 0A limit to the GX or DVCC is set to 0A, the maximum charge current is now -0.30A indicating a slight discharge. Behavior has been consistent between today and yesterday.
This is consistent with past DVCC charge limitation operation on my prior FLA battery bank - I would have it set for 30A max and never see more than 29.7A into the battery (0.3A shy of limit).
