Technical Durite split relay problem

[archibusa]

Good morning guys.
I have fitted a durite split relay in my doblo with one leisure battery. But the problem I have Itwill only charge the leisure battery sometimes. When I start the van the durite relay light will stay off then sometimes it comes on. Has any one had this same problem. Cheers Archie

 

[mu0chn]

Have you checked the voltage when the engine is running.