Urgent question

[tonysmith]

We have a 2017 Montana 3820 FK. Have not taken it out yet. Not new to RVs or 5th wheels. It is under a solid cover. Today, I pulled in the slide outs and hooked it up to my truck. All while plugged into the shop. Pulled it out to cut and kill the grass. Pulled it back in. Decided to be sure that it worked on just battery. 6 point leveler worked, generator fired up when I tried, but the main control panel inside is dead. No lights, no refrigerator, no water pump, nothing. Plugged it in, everything is ok. Checked the batteries, all good. What am I missing. Checked the breakers. All good. Thank you.

[hankpage]

Battery disconnect???????

[tonysmith]

Checked that as well. When I turned on the disconnect, it kills everything. Weird. Seems like a breaker or fuse somewhere.

[hankpage]

Were your batteries disconnected for storage??? When reconnected was polarity reversed???? On RV Black is POS +!! If reversed for even a second the 40 amp fuses on the converter has blown isolating the battery from the system.

[chuckster57]

UNPLUGGED FROM SHORE POWER:

Start at the battery positive post. Using a Volt meter, check voltage to ground. Then start tracing the positive wire, there may be an inline fuse or resetting circuit breaker, probably mounted somewhere between the junction box and battery. If nothing then find the junction box.
Easiest way on a fiver is to just follow the umbilical cord. Take the cover off and look at the MESS of wires. Make sure all the BLACK zones are still connected, and test for voltage there. If none then the problem is the battery feed, if there is power then you need to go to the fuse panel and start at the reverse polarity fuses.

[tonysmith]

Never disconnected the batteries. Where is the 40 amp fuse located? Thanks

[tonysmith]

Will start the detective work and report back. Thanks to all.

[chuckster57]

Never disconnected the batteries. Where is the 40 amp fuse located? Thanks
look at the 12V fuses side of the breaker/fuse panel. There is a vertical row of fuses, probably all 15A and off to the left should be the 40A. If the converter is a plug in type (probably what you have) there is 2 fuses on the back side where the large leads hook up.

[hankpage]

Will start the detective work and report back. Thanks to all.

Usually on converter but if polarity was not reversed they should be fine.
Follow Chucks advise and start tracing wires starting at the hot battery lead to the compartment wall. Good luck, Hank

[2Savages]

I have a 3820, but I am not familiar enough to offer any help. My unit has an In- Command Panel, which should be DC and usually I only have Bluetooth sync issues. A few weeks ago the AC volts stopped working at the campgrounds and caused us some head scratching. The trailer DC was fine and I checked fuses at the fuse panel before going outside to find the shore power CB had popped due to a electric frying pan and microwave maxed out the 30 amp. I also noticed the generator continued, to have a source of power to it after I had switched the battery power off. The red light on the start button was still on when closing up. One side of the 2nd battery is connected to the genset. Good Luck, I would be interested to learn from your outcome.

[WaltBennett]

Might ask the Montana Owner's Club forum. Several electricians and RV techs there.

[tonysmith]

OK, I am at fault. Somehow when messing with the Waterhouse connections, I hit the battery disconnect enough to lock out the batteries. I was under the impression that the disconnect would lock out all battery powered things. Not so, only a select few. Thank you everybody for your input. Happy camping.

[notanlines]

Thanks for the answer, Tony. We have all travelled down that road once or twice......I know it well.