question

Does this also happen at a low SOC state? Does the wiring of that unit have another length than the other ones? What happens if you put a very heavy load above the charging power on the Quattro for more than 5 Minutes? Will the charge controller continue?

This happens every day within the times I stated earlier. The system has been working perfectly up to this week. No extra wiring has been introduced and the loads are the same ones that have been running off the Quattro since we completed the installation.

Assuming a reasonably even drain of the batteries every night, then at the daylight the SOC would be very close each day. Assuming the amount of charge going onto the batteries each day is near enough the same.

My mind is saying look for a slightly defective connection, particularly the tightness of the screws on the 150/70 battery connections. Also check voltdrop between the controller is less that 0.5%.

I do not know how far apart the 150/70s are but I would be temped to change the cables to the batteries over between one good one and the one causing concern.

If the problem moves to the good one, then it is probably a problem with the cables and the connections on the way to the batteries.

If the problem stays with the original 150/70 I would do a full reset to factory defaults and then reset to the required parameters. If that clears the problems there is a possibility the control firmware went off.

If not would need to think some more.