Best Practice for D+ Wiring with Dual Generators and BMS Setup

DIY
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1

Dear all,

I’m currently running into some issues with my setup and would appreciate any advice, shared experiences, or guidance.

Here’s my situation:

I have two generators connected as shown below:

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However, to make the system run smoothly, I’ve had to disconnect the D+ wires from both generators.

  • When Gen 1’s D+ is connected to the start battery, it becomes overcharged, and the Volvo Penta system triggers charging malfunction alarms.
  • When Gen 2’s D+ is connected to the service battery, the BMS shuts down the service battery due to high voltage.

As a workaround, I’ve disconnected both D+ wires and now rely solely on the B+ measurement from the generators. While this avoids the issues above, it also results in reduced charging current.

My question is:
:backhand_index_pointing_right: What is the best practice for wiring D+ in a dual-generator setup like this?
Any insights on managing D+ in relation to smart BMS and start battery protection would be greatly appreciated.

Thanks in advance for your help!