Ignition cut out (click) on TD5 split battery system

My 110 TD5 has 2 batteries (both at around 90%) & a split system. Lately the ignition initially fails. It looks as though there might be a short somewhere. After a few minutes I enable the Auto Charge & the no 2 battery kicks in & the vehicle starts. Not ideal. I'm wondering that the charge from the 2 batteries isn't quite enough. I'm running a fridge, safari light bar, CB & several other indicator lights. Has anyone any thoughts on how to fix this ignition issue ?

Here's the battery bay. The back up is a Yellow Optima but the principle battery....any thoughts ?

I would lose the post code are the battery's fully charged, have you checked the battery earth connection on the main battery

mystery said:

I would lose the post code are the battery's fully charged, have you checked the battery earth connection on the main battery

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Thanks. Any idea what the orange wire might be ?

Had the same last week but single. The battery was changing to full with external charger would be ok for 2 days then die started with a click from the starter could be one is all most dead and is draining the other . I put on a new battery and all ok voltage and amps have not altered

I'm changing the starter motor. Solenoid. Let's see what happens