Engine battery not charging off mains

[Strollerbird]

Any help or advice gratefully received.
When we put our motorhome in storage we would occasionally plug it in to charge both the leisure and the motor battery. On the last couple of occasions we have found the leisure battery fully charged but the engine battery dead.
Where do I start to look to solve this?

 

[YeoBlade]

Model of motor home? Is there a switch to change over charging?

 

[trevskoda]

Do as i did, connect a heavy battery cable through a 200amp relay and a dash switch, also handy for a jump start if you forgot to turn lights of.
Or as many do a rhine wire fused at both batteries, just pull the fuse when using the van.
Also is it the van charger which most are junk, best fit a smart charger of around 10amps or more, this with above wire will charge the lot and cycle to desulfer and maintain them.

 

[Phantom]

Maybe a fuse? Ours had a small device that charged the SB at up to 2Ah from LB until if stopped working!

 

[MERL]

I do hope Phil's got this issue covered in his new book because this issue and three way fridges not working on gas has been done to death.

Are you saying that the starter battery used to get maintained when on EHU but now it doesn't?

If so are you taking about the same van?

Can you post a picture of your electrical control panel, that'll help massively.