I live in Montana. I remove my RV’s dual 12v batteries and bring them inside. Then I plug my trailer into shore power to run a small heater. I discovered that I cannot use my slide function without the batteries hooked up to the system. What is the purpose for wiring it that way? Shouldn’t it be set up to also work off shore power? —Mark, 2019 Northwood Arctic Fox 25W
Almost every slide-room mechanism uses 12-volt power to run the motor that extends and retracts the room. That battery is the house battery system, which could be two 6-volt batteries connected in series or a traditional 12-volt deep cycle battery. The 12-volt power is provided by that battery bank through the distribution center and a fuse to the slide room motor or motors. The house battery/batteries are charged by a converter, inverter/charger, or solar panels.
What’s the type of converter and how are the batteries wired?
To answer your question, we need to know the type of converter you have and look at how the batteries are wired. Converters are simply battery chargers and some of the new chargers need to have an actual connection or battery as a buffer. I just purchased a new battery charger from NAPA. A neighbor left their lights on so the automotive battery was dead. I hooked up the charger and nothing! Since the battery had gone below 2 volts, the charger has a safety feature that prevents touching the two leads and creating a spark, so it will not turn on until it senses voltage. That means you need a battery between the leads. I had to install a 12-volt power supply I use for bench testing to get it up to a few volts, and then the charger kicked in.
However, the WFCO converter we pulled out of the 2015 Thor Challenger will provide 13.6 volts with nothing connected. We installed lithium batteries and changed out the WFCO with a Progressive Dynamics model recommended for lithium. I would suggest finding your converter and use a multimeter to see if there is 12-volt power coming out of the converter without the batteries connected. Your converter will either be an all-in-one as part of the distribution center, or be a standalone, like ours was.
This converter will provide 13.6 volts when it senses a low battery or no battery at all. It then drops to 13.2 volts when the battery is fully charged, as this is the maintenance or float charge. If you do not have voltage coming out of the converter, it is the voltage-sensing model and will not provide 12-volt to the distribution center.
But if it provides voltage
If you do find it provides voltage, the next place to look is the wiring or cabling at your battery center. Some RV manufacturers use several cables going to different relays and battery isolation management (BIM) systems or solenoids. If you removed cables, it may have created an open circuit and you will need to connect all the positive cables together.
This was the rat’s nest that was in the Thor. You can see there are two cables on the positive side that would need to be connected to provide power to the distribution center if the batteries were disconnected.
You might also enjoy this from Dave
How should the RV’s 6-volt and 12-volt batteries be wired?
I have a Class A diesel pusher motorhome with two 6-volt and two 12-volt batteries. How should these batteries be wired? Any info on this would be appreciated. —Carla, 1999 Overland Lorado
Dave Solberg is a leading expert in the RV industry and the author of the “RV Handbook.”
Read more from Dave here.
HAVE A QUESTION FOR DAVE?
We have a forum link for Ask Dave. Please be as brief as possible. Attach a photo or two if it might help Dave with his response. Click to visit Dave’s forum. Or send your inquiries to him using the form below.