Can you please help troubleshoot the issue with this installation (see enclosed diagram)?
I am not an electrician or an engineer and my diagram is very simplified to give an idea of the installation (negative wires and fuse omitted). There is a fuse between the lithium batteries and the installation, and another one between the AGM batteries and the installation.
The goals of the installation are:
When the alternator is off, charge the AGM batteries from the lithium batteries through a Orion-Tr Smart charger.
When the alternator is on, charge the Lithium batteries through 2 Orion-Tr Smart chargers.
When the alternator is on, charge the AGM batteries directly from the alternator (without chargers in-between).
When the alternator is off, it is working correctly (AGM batteries are charged from the Lithium batteries through the Orion).
When the alternator is on, I observed short voltage spikes (of up to 40V for a few seconds) on the input of 2 of the Orion chargers and the output of the other Orion charger. I did not have time to measure it elsewhere, but it suggests that the line from the alternator to the AGM batteries was having those spikes.
Upon seeing these spikes, I turned off all 3 Orion chargers from Victron Connect to avoid damaging the batteries. When the chargers are off, the alternator output a stable 28V (27.95V measured) to the AGM batteries without issues.
What can cause those voltage spikes and how can I fix it?
I think your problem is the input to the 2 Orion chargers feeding the lithium batteries is isolated from the AGM battery by the Argofet. The Orion chargers need the AGM battery to buffer (smooth) the voltage response. Look at all the Victron diagrams for Orions, the alternator connects to the lead acid battery and direct to the input of the Orions.
Try the system without the Argofet and the lithium to AGM Orion turned off. I am sure the alternator will then charge both batteries.
The on thing you need to be careful about is setting up the lithium to AGM Orion so it only charges when the alternator is off, you can do this by setting the output voltage of the lithium to AGM Orion to a lower voltage than the alternator output. If the battery is higher voltage than the Orion setting then it will not charge.
It makes sense. However, if the end goal is to charge the AGM even when the alternator is off, then I cannot remove the Agrofet permanently. If I do, the output of the Lithium->AGM charger will be connected to the input of the Alternator->Lithium chargers (via the AGM battery).
It will create a circular charging pattern where the Lithium->AGM charger raises the voltage of the AGM battery, which is connected to the alternator and the input of the Alternator->Lithium chargers. This raise voltage will activate the Alternator->Lithium chargers.
What I could do is remove the Agrofet, and connect the Alternator->Lithium charger remote sense H-pin to the D+ output of the alternator. In that case, these 2 chargers would only be on when the alternator is also on, and completely be turned off when the alternator is off, even if the input has a high voltage due to the AGM charger. Right?
