General Electrical Question - Battery Installed Incorrectly

[droidguru]

I know all rigs are different and I'm not 100% that Coachmen and GD's electrical systems are set up in an identical fashion so chalk this up as a general electrical question to give me knowledge about how the battery functions in our rigs.

This weekend a friend called me up and told me about an issue he was having with his Coachmen. He said his slide was reversed (in button caused the slide to go out, and out button caused the slide to go in). Also all of the lights were dim and the outlets didn't work at all even though he was hooked up to shore power. I asked him if he had been drinking and he replied no, then I said I would come and check it out.

After about 30 minutes he actually diagnosed it, he had crossed the terminals when he installed his battery (negative to positive and vice versa). So he reversed the wires and I knew the converter fuses must have blown so I replaced those as well. To my surprise the in-line fuse at the battery wasn't blown? This got me thinking. Someone correct me if I'm wrong. The converter is what charges the battery, so if the converter fuses were blown then the battery was protected correct? I originally told him that he was lucky that it didn't burn down the rig, but in saying that I was wrong since once the converter fuses blew the battery was basically cut out of the power system except for the power out with reversed polarity which is why the slides were moving in the wrong direction.

I don't know a whole lot about electrical but I told him to have the battery tested and replace it if necessary, but that might not be necessary if I have the right thoughts on how the battery is charged right? Also is there anything else we may want to check in the rig or test before it heads out for the season?

Short of it is if your slides are ever operating in the reverse direction check your battery and be prepared to replace some fuses. Thanks for the advice.

[Cate&Rob]

Hi droidguru,

Connecting the battery backwards won't likely damage the battery . . . but definitely could damage things connected to it.
Particularly electronics can be polarity sensitive. Entertainment system components ? Controllers for fridge, water heater, furnace ?? Unless the battery is being removed, there is no need to disconnect both terminals. Just disconnecting the negative (black) cable will completely isolate the battery and leave what needs to be done to re-connect, completely obvious to anyone.

Rob

[droidguru]

Thanks Rob.

I'll head over there next weekend and help test out everything. Their first trip is to Indiana (and he is located in Delaware) so I would hate to have them head out and arrive to find their fridge doesn't work.

That being said as far as I know he only hooked up the battery and never turned on anything except to put the slide out......so hopefully he didn't do too much damage. Looking at the silver lining at least the battery is ok!

[Dave and Monica]

The converter and the battery both feed the 12V DC fuse panel. When plugged into shore power, the converter produces at least 13.2V DC to the DC wiring including the battery and can switch to 13.6V (adsorption mode) or 14.4V (boost mode) if the demands on the 12V DC in the camper require it. No power to the converter, only the battery supplies the 12V DC requirements. The wiring to the slide drive in the Coachmen may be directly from the battery with in-line fuse or CB or from the 12V fuse panel. Either way if you reversed the battery leads the slide drives will still work though reversed from normal direction. He should have noticed the same with his landing gear or stabs. I believe that the in-line fuse or CB at the battery wouldn't blow as it's only sensitive to amperage not voltage polarity.

He should still verify that the converter is working correctly with new fuses, the furnace, fridge and water heater as all have a 12V DC control board.

Dave