Interesting Battery change story

[LandKO]

The chassis and house batteries in our Freedom Elite 30FE were approaching 4-1/2 to 5 years old. In preparation for an upcoming Florida trip, I decided to invest in new batteries. I replaced the original “flooded” batteries with AGM batteries primarily because they are maintenance free and the warranty was better.
Before beginning with the replacements, I disconnected shore power and turned off the Main Power switch by the steps.
I used good maintenance practice by disconnecting the negative terminals first and reconnected last.
The chassis battery replacement went smoothly, no issues.
The house battery replacement didn’t go as smoothly.
After reconnecting the new battery and restoring shore power I discovered that there was NO 12v power at all in the MH.
I checked continuity between the battery terminals and the connectors and found it to be good.
When I tried engaging the Main Power switch, I could hear a relay clicking back by the main power panel..
When I looked in the power panel I saw a small placard that referenced reverse polarity fuses. There were two 40a busman fuses at that location so I removed both of them and found that both were blown. I don’t know why they blew because I did not hook up the battery backwards.
I replaced both 40a fuses and now have 12v power back in everything except at my Bigfoot Leveler’s control panel. I don’t know if the loss of power at the control panel is due to the battery change or if it pre-existed since the MH has been stored the last couple of months.
I’ll call Bigfoot tomorrow to find out if there is an inline fuse in their system.
I find it strange the both 40a fuses blew but I guess that was good if there was a transient spike in power. They saved everything else.

[Grumpy Grampa]

Double check the wiring on coach batteries. Just be sure batteries are wired correctly. Pictures before to refer to when reinstalling.

Keep us posted.

Good luck