I'm installing Lithium "house" batteries and an AGM engine start battery on a sailboat. They are isolated on always separate circuits for safety. The solar is charging the lithium and I have a Victron B2B charger on a switch to occasionally charge the AGM from solar via the lithium bank. The engine alternator charges the AGM and I have a Renogy 40A DC-DC charger to transfer the alternator charge to the lithium bank. I plan on using a common negative bus bar for both banks. Is that OK?