Hello,

for the connection of two Battery Banks i need a little help about which Product is for the application the best.

In my Truck I have two Battery Banks.

Bank 1 are 2x 260Ah Varta AGM 24V

Charger of this Bank is a 110A 24V Alternator (and a Victron Blue Smart 24/13A Charger every 2 times per month)

Loads are the Starter for the Engine and a small DC Air Condition.

To monitor Bank 1, i use a SmartShunt IP65 which is connected to the Cerbo

Bank 2 are 4x 200Ah (2 more are coming) Victron Lithium 24V Battery's.

Charger of this Bank is a Skylla i with 80 A

Loads are a Phoenix Inverter and smaller DC Loads

To control/monitor Bank 2, i use Lynx Smart BMS which is connected to the Cerbo

Case 1

While driving Bank 1 is charging by the Alternator with max 110A

When it's full, i want to charge Bank 2, when the BMS ATC (allow to charge)

Case 2

While standing Bank 2 is charged by the Skylla i with max 80A.

Bank 1 with 4A (second connection at the Skylla)

When it's full, i want to charge Bank 1, when the BMS ATD (allow to discharge)

Which product can manage bidirectional charging and is able to stop charging Lithium Bank (because low temperature) but allowed discharging at the same time?

Or charging but not discharging?

My quick and dirty solution is to use two relays and two diodes in parallel.

Relay 1 is connected to the ATC from the BMS and let with the diode current only from Bank1 (AGM)

to Bank 2 (Lithium)

Relay 2 is connected to the ATD from the BMS and let with the diode current only from Bank 2 (Lithium)

to Bank 1 (AGM)

To protect overheating Alternator, i build in a temperature sensor inside the Alternator which disconnect a third relay (AGM to Lithium)

This relay is connected to the SmartShunt as well and prevents too low discharging of Bank 1.

Please let me know if this ideal is brilliant, stupid, dangerous or not necessary because one product can handle this….

Best regards Robert