HELP with ELECTRICAL ISSUES!!!

Ok.... I'm new here and I need some help and/or advice.  First of all I I'm the new owner of a 2007 Fleetwood Niagara!  Here is the issue, we set it up when we got it home and after we had checked it over put it back down and away in the shed.  While we had it up we had it plugged in to "shore power".  Three days later we set it up again to get ready to go camping and the battery was TOTALLY dead!!!! The man we bought the camper from had just put a new battery in it and he gave me the receipt, so I know it was new.  Ok... so I start checking, and checking, and checking!!!!  At the battery, with everything shut off, I could take and hold the positive on the battery and just scratch the negative on the negative post and get a good spark.  That told me that there was something still "drawing" on the battery.  So I started unhooking things.... taking fuses out.... flipping breakers..... unhooking lights.... you name it, I probably tried it.  I also got continuity between my positive on my fuse panel and my negative.  Then I noticed a fuse labeled "REVERSE BATTERY" which is located between the positive and negative terminals on the fuse panel.  I pulled it and low and behold.... no spark and the battery and no continuity between positive and negative on the fuse panel!!!!  The fuse is NOT blown.  Also, below the "REVERSE BATTERY" fuse there is a fuse slot labeled "PROTECTION FUSES".  There is not a fuse in this slot.  Ok, enough rambling..... What do you make of all this?  What am I missing?  Can I leave the "REVERSE BATTERY" fuse out?  What is the deal??????  Thanks for any and all help!!!!

I'm not certain, but in many electrical applications "REVERSE BATTERY" is a protection circuit that protects the rest of the system in case the battery is connected reverse polarity.  It can short out an ECM on a diesel if not in place, and maybe the computer on a gas unit as well.  I'm not sure I would want to leave that out.  It should blow if you reverse polarity, or short something out.  Leaving it out could present a fire hazard.  I'm sure someone else will correct me soon.  Just disconnect at the battery until then.  Mine has a switch at the house batteries that when open the batteries are disconnected.

Hi Chris - welcome to The RV Forum!

Some converters have capacitors that charge up when you first touch the wire to the battery terminal, and this creates a momentary current surge that can create a big spark.  Once capacitors reach full charge (it takes less than a second) they stop drawing any further current.  If it's just the capacitors charging you should be able to remove the wire and touch it to the battery again within a couple of seconds without getting a second spark.  If something is continuously drawing current, you'll get a spark every time you touch the wire to the battery post.

The Reverse Polarity fuse is usually in line with the converter, because if you hook up the battery backwards the converter becomes a dead short across the battery.  If this happens, the fuse will blow to prevent further damage.

Look for a storage compartment light that may have been left on.  If your trailer has electric brakes, you should have a lanyard that will pull a pin out of a socket if the trailer becomes disconnected from the car and apply the trailer brakes. It will be near the trailer's hitch socket.  Make sure the pin is fully seated, since the trailer battery supplies power to the brakes when the pin is pulled out.

Ok.... Thanks for the replies so far.... I think I understand with the capacitors.  I will check the trailer brake safety.  I have checked ALL the lights.... in fact I took all the other fuses out, and flipped all the breakers off.  In other words, from the "power into the trailer" I disconnected EVERYTHING else.  All I had hooked up was just my white to negative and my black to positive.  At that point I could take a continuity tester and get continuity between the positive and negative terminals on the fuse panel.  This is with the REVERSE BATTERY fuse in place.  If I take the REVERSE BATTERY fuse out, I do not have continuity between the positive and negative terminals.  Ok..... Thanks again for the help!!! 

Ok... Clarification!!!  Dumb me!!! When I had been checking for continuity between the positive and the negative at the fuse panel I was not watching the positive and the negative on my tester.   So, if I check for continuity at the fuse panel, positive on positive and negative on negative hooked up correctly, there is NO continuity.  BUT...... I'm still getting some spark at the negative terminal on the battery when I hook and unhook it.  I've tried taking out fuses, one at a time, to see if I can isolate the problem.  No luck.  If I take all the fuses out I get NO spark.  But as I put the fuses in I get spark.  It makes no difference in what order I put them in.  Ok... I hope this all makes some type of sense!!!  Maybe I'm too picky, but I don't want to get out in the boonys, running on battery, and all of a sudden I have no power!!!  Again thanks for any and all help!!!

I hope you're not measuring continuity with the battery connected.  That's a sure way to burn out your meter and it won't give a meaningful reading with any voltage on the points your measuring across.

A bit about condensors 9r capacitors as they are also called.

They are kind of like mini batteries,  They accept and hold a charge (not much of one, like one amp second for a really big one) thus when you first connect a battery, they will usually be "low" and accept current very very very fast (A meter whill show near short) but only for a brief period of time.

If you put an ohm meter on one it will start out with a near short reading and over time (how much depends on too many thigns to type today) the meter rises to near open circuit.. Reverse the leads and not only will it go down PAST zero, but you may burn out  your meter. (not likely) then it comes back up again

That said:  If you have an internal short in the converter.. It should blow the reverse fuse but who knows.

It sounds to me like there are two fuses involved the the labels you found and it  applies to both as in "REVERSE BATTERY PROTECTION FUSES"

There is likely diodes involved here as well that permit current flow if the correct polarity is present and will block it if reverse polarity is detected. The fuses and circuits are designed to blow should the battery be connected in reverse thus saving your skin and likely the converter/battery charger that doesn't like being connected backwards.

Rather than trying to reverse engineer a good system, simply install a battery disconnect switch to turn off the battery (as opposed to disconnecting the battery cable each time) while the trailer is going into storage and you can likely forget about this problem. These switches can be found at any marine store. Look for a simple one with only Off/On capability.

BTW, running with only one battery in the boonies, the chances are very good you will run out of power unless you practice some very strict power conservation. Don't expect a lot of time on that system.

Cris said:

Ok.... Thanks for the replies so far.... I think I understand with the capacitors.  I will check the trailer brake safety.  I have checked ALL the lights.... in fact I took all the other fuses out, and flipped all the breakers off.  In other words, from the "power into the trailer" I disconnected EVERYTHING else.  All I had hooked up was just my white to negative and my black to positive.  At that point I could take a continuity tester and get continuity between the positive and negative terminals on the fuse panel.  This is with the REVERSE BATTERY fuse in place.  If I take the REVERSE BATTERY fuse out, I do not have continuity between the positive and negative terminals.  Ok..... Thanks again for the help!!!

Click to expand...

Somehow this does not seem right for 12VDC.  Normally black is ground and white/red is hot.  On 120 VAC it is as you describe. Black is line voltage and white is common/neutral.

First I would suggest the battery cutoff switch for storage as suggested above. This eliminates any phantom draw problems when storing the unit.
By looking for "spark" when touching the battery cable you cannot really make any progress with this method. As Lou suggested you can't see the difference between a large continuous amp draw or just a capacitor charging. Go to Walmart and for app $15 pick up a VOM. This will be able to read DC current up to 10a. Install the VOM and check current draw as you install or remove fuses. Something is obviously pulling enough current to draw the battery down so now when you pull fuses you will be able to see the current draw go down. Even a system operating normally can have a spark when the cables are removed, it does not always indicate a large amp draw. When you are down to app 1/2a or less everything is pretty close to normal. Then shut off your new battery disconnect and you are ready for storage. If your battery is new it should last for more than 3 days in storage when properly charged. JM2C, good luck with it.