Coach battery not holding charge

[was_butnotnow]

I have a mew to me 05 Monaco Cayman 36 DPQ
Replaced all the house and coach batteries and added 600 W solar.
The Solar controller has a 2 A trickle charge for the coach batteries. It is putting 2 A into the coach bats.
But even with the battery switch OFF they won't hold a charge. Goes to like 8 V but with the power boost can start the MH.
Should the 2 A charger keep the new coach batteries charged?
We are camp hosting so not starting the MH every day.

[DrewE]

I assume by "coach" you mean the chassis battery. (Coach battery usually refers to the house battery.)

2A, even intermittently available, ought to be sufficient to keep it charged if there is no load beyond typical vehicle parasitic draws. I'd suspect something left on, like maybe parking lights or some gizmo plugged into a dash lighter socket or the dash light, or else some fault or incorrect wiring up causing a battery drain.

Maybe, if you have a BIRD sort of isolator (a bidirectional relay control, so it is designed to charge the chassis battery when the house battery is being charged), it's getting confused by the charge path around it from the solar controller and activating most all the time...though I don't see how that could run down the chassis battery so deeply.

[Playtime_II]

Inverter left on?

[MountainAir05]

Sounds like you have something really drawing on the battery. 2 amp really will only keep a full battery charge , not one that has a draw on it.