question

To expànd. Just before 02:00, input voltage dropped. This caused the charger to switch off. At the same point the load measured on the shunt dropped to zero, not the 1A previously. The shunt will only show current through the battery. At around 04:30 charger input voltage increased allowing charging to restart. It was not due to rebulk offset.

It looks as if battery voltage did drop significantly at your point 2 around 04:30, but it's hidden by the current line. This also doesn't explain the sudden increase in battery voltage and charge current at that point, the system was already in bulk. It seems the input current to the Orion was restricted, as well as it having a lowish input voltage.

The Orion is voltage driven. And as the manual says, it's output is simply to maintain voltage, not current limited in float/storage. Battery resistance controls the output current to the battery.

The questions here are

1. Why did input voltage drop
2. What caused battery voltage to drop when the shunt recorded no current.
3. Is the system correctly wired
4. Is there another charger kicking in on the input side of the Orion?

Thank you for the reply. I've zoomed into the 4:30 area. My interpretation is

1. The system load was continuous between 12W and 16W throughout.
   
   
2. At 4:34 the system was in equilibrium in storage mode. The charger was providing around 1A output which was maintaining the battery and supplying the load. So SmartShunt was recording very little current (-0.2A)
   
   
3. At 4:36 the charger switched off for some reason (why?). Input voltage was still 13.88V. Output current dropped to 0, so the load was then supplied by the battery. Smartshunt shows -0.9A
   
   
4. At 4:39 the charger switched into bulk, causing the input voltage to drop.
   
   
5. There are 2 missing data points for Charger Input Current at 4:37 and 4:38 which is why the shape of this line does not broadly match the output current.

So to answer your questions.

1. I think Input voltage dropped because bulk charging started, not before
2. Battery voltage (SmartShunt) doesn't appear to drop below 13.3V
3. Yes. Nothing connected to -ve battery terminal except SmartShunt. Victron components are SmartShunt, Orion XS, SmartBatteryProtect, SmartSolar 75/15, Cerbo GX.
4. The leisure battery is 12V 128Ah LiFePO4. The input to the XS is connected to the AGM starter battery which is charged by the engine alternator, and also in this case by a AGM mains charger. This charger can supply approx 15A. At the 4:30 point in the graphs, the AGM battery had been charged and was in float mode at approx 13.8V.

4:34

4:36

4:39