One bank of batteries not charging

[boatymcboatface]

Hi Tugnuts,
My thruster generator batteries don’t charge unless I put them in parallel. The ACR is flashing green lights not sure what that means but batteries in this bank don’t charge even from alternator. The batteries are new just don’t know what to look for or try to fix. Any suggestions?

 

[knotflying]

Fast flashing usually means under charged. The relays will lock out a battery if it is below the threshold voltage. The parallel switch usually joins the house bank and engine battery, not the thruster. I suspect that the thruster battery is below voltage.