Modifying the coach battery box

[UKDUDE]

I was looking at my coach batteries with a view to attaching quick-connect cables to the battery posts for easy trickle-charging - CTEK has a quick connect cable with eyelet terminals for that purpose.
But after removing the plate at the back of the battery box and sliding out the battery tray, I can see the box is pretty-well sealed apart from an exterior vent that goes out through the passenger side.

I wanted to drill a hole in the box to route the quick-connect cable so I could plug in the charger without having to remove the back plate and slide out the tray.

Is this a bad idea? I was wondering whether the sealed design of the box was to prevent any hydrogen from escaping inside the RV.

Thanks….Peter

[Boxster1971]

I'm looking at the same issue to install a battery temp sensor wire for the Blue Sky Solar controller I'm adding to upgrade my solar system. I think you want to keep the battery box sealed even though the claim is that AGM batteries used by Airstream do not vent under normal conditions. For my single temp sensor wire I intend to drill a small hole, add a grommet and some silicone sealant.

If you plan to charge your house/coach batteries in parallel (i.e. together) with the CTEK unit you may be able to attach the quick-connect cable in another spot. The Airstream installed solar controller just feeds the charge current in at a terminal strip below the battery cut-off switch under the lounge seat in my unit. It's not critical to attach the quick-connect directly to the battery terminals. For example to charge the vehicle starter battery I attach my CTEK clips to the remote jump start terminals in the engine compartment for a battery installed under the driver seat.

[Protagonist]

Originally Posted by UKDUDE

Is this a bad idea? I was wondering whether the sealed design of the box was to prevent any hydrogen from escaping inside the RV.

Exactamundo!

Hydrogen rises, and the battery box is vented to the exterior of the van near the top, but supposedly sealed all around, except for another vent in the bottom to let in fresh air. So if you drill a hole in the side near the bottom, and put a rubber grommet in the drilled hole to protect the wires from chafing, you should be golden.

That leaves the existing vents open to do their job, and avoids the risk of venting hydrogen inside. Not that AGMS give off much hydrogen…

Side note, the battery box is painted steel, so after you drill the hole, paint the fresh edges before you put the grommet in. That will help prevent corrosion.