question

Some details of you system, what type of batteries, Orion, MPPT and where are you getting the SOC from. When charging what voltage do the batteries get up to according to the MPPT, Orion and the BMS or shunt. Screenshots of your settings and the chargers working may help to diagnose. Check all your connections are tight and crimps are tight. How did you size your cables to avoid voltage drop. Do you have the resettable breaker like shown below, these often do not work very well and cause voltage loss.

Orion charging on Absorption a couple of minutes after the engine was turned on. Battery SOC 77%

Screenshot showing all the battery voltages when just the Orion is charging.

MPPT charging with the engine off. It is morning, but there is still full sun on the panels at the moment.

History of Solar last few days (all at 70-80% battery and in sunny conditions in Spain).

Screenshot showing battery voltages when just the solar is charging.

Again. Massive thanks in advance.

Angus

I have had a look through everything and your settings appear to be mostly OK as far as I can tell. The only thing that I would change is on the SmartShunt I would increase the charged voltage from 13.8V to 14.2V as this will make sure that the batteries are truly in absorption phase before the SmartShunt goes back to 100%.

Before going further, do you get your batteries back up to 100% daily or frequently rather than continually running them at less than 100% for long periods. If you are not getting them to 100% frequently then they will slowly age and reduce in capacity. This is complicated because the SmartShunt may be going to 100% before it is full.

A second question, have you put these devices onto a Smart Network so that the SmartShunt shares the battery voltage and current. It appears not but it is worth confirming.

A third question is why the absorption is set to 14.6V on the Orion and 14.4V on the MPPT although both are within the recommended range, it may be less stressful for the battery to have the Orion also set at 14.4V as that is in the middle of the 14.2 to 14.6V range.

From the data you have supplied, when the engine is running the Orion is kicking in and charging, but it is charging at well below its rated output despite the low battery. It is hard to completely be sure what is happening. The Orion is measuring 14.6V at its output, the MPPT 14.56V and the battery protect 14.56V but the SmartShunt is measuring only 13.12V. I do not know how these are all wired or if the SmartShunt voltage is wrong. If you have everything connected to a bus bar then there may be a high resistance between the busbar and the domestic battery which is fooling the chargers that the battery is at a higher voltage so that they are not getting charged fully. You need to check this with your multimeter to see if when the Orion is running, are the domestic batteries at the battery terminals actually getting up to 14.5 to 14.6V. If they are then your SmartShunt is reading too low voltage and the SmartShunt positive sense wire will need checking.

When the MPPT is running there is a lot more conflicting information, the output of the MPPT is only 9.71V but the SmartShunt reads higher and the Battery Protect is obviously below 11.5V but not known. In this case, I believe that this shows you have a high resistance between the battery and the bus bar, the battery voltage is OK but due to the high resistance it can not provide enough current to the bus bar to meet the load demand and there is not enough solar to provide this either so the voltage on the bus bar falls very low. Again, you could check this with your multimeter.

Therefore, in conclusion, the evidence points towards a high resistance between you domestic busbar and your battery terminals so check for voltages at the battery and busbars and voltage drop in this area and check all fuses, isolators, cable crimps, terminals, bolts etc and you may find something loose or not working.