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Topic: New Batteries & Reverse Polarity (Read 5 times) previous topic - next topic
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New Batteries & Reverse Polarity
Yahoo Message Number: 56290
OK, I think I really screwed up.
 Before I took the old Trojans out, I drew a picture of how they were installed, but mistakenly reversed what went with the black wire and what went with the red.  When I installed the new batteries, the reefer and the converter made funny crackling noises, so I disconnected and finally realized what I did.  I think I have it correct now....black wires to negative....red wires to positive, and the other positive/negative connected.  The problem is no lights, no pump, no reefer but the instrument panel works.  Fuse for the pump is OK.  Fuse for the reefer looks ok.  Did I fry things?  I'm going to go back tomorrow and check all the fuses again, but assuming all those are OK, what's the fix?  I looked in the LD manual, but no troubleshooting ideas.  I looked in my RV fix-it book, but no ideas there either.  Thanks in advance.
 PS-it looks like the cab fuse for the instrument panel may have blown as well as the idiot lights that usually light up when the ignition is on do not light up...and the alternator guage, temp gauge and oil pressure gauge are not functioning either.  Chevy manual shows one 20 amp fuse for these items, so I'm hoping that's the problem there.

John & Cheryl 1989 22' RL Big Red
Re: New Batteries & Reverse Polarity
Reply #1 –
Yahoo Message Number: 56303
Quote
reefer and the converter made funny crackling noises, so I disconnected and finally realized what I did.  I think I have it correct now....black wires to negative....red wires to positive, and the other positive/negative connected.
It sounds like damage could be extensive, I'm afaid, and no way to know without tearing apart the electrical system. However, the light bulbs should be ok, and fuses should have protected the 12V wiring.

First, I would pull the converter and have it checked out. If original, you might want this to be the opportunity to upgrade the DC power supply and battery charger sections, which is where the damage will be. Any electronics plugged in could have been damaged, such as fridge, furnace, possibly water heater controls (if electronic), in-dash radio/cassette, 12V TV / DVD player, diode isolator, and potentially the alternator and GM/Ford chassis electronics. Replace the converter, then check each system completely.

Steve
2004 FL
2013 Honda Fit
Re: [Life With A Lazy Daze RV] Re: New Batteries & Reverse Polarity
Reply #2 –
Yahoo Message Number: 56324
It sounds like damage could be extensive, I'm afraid, and no way to know without tearing apart the electrical system. However, the light bulbs should be ok, and fuses should have protected the 12V wiring.

Well, good news.  I went back this AM to check the fuse for the instrument panel, a 20 amp, and sure enough, it was bad.  Replaced it and the chassis instrument panel came to life.  Then I checked all the fuses for the coach, and they were fine, so I figured, what the heck, why not connect the house batteries?  Well, everything worked!!!  Reefer fired up.  Pump's working.  All the lights are working....and no funny crackling sounds.  The only things that aren't working are the CB and the radio, but they weren't working before this problem began.  I replaced the CB and radio fuses, which are on the firewall of the chassis, but that didn't do the trick either.  But I can live without a CB and a radio....and someday I'll troubleshoot those problems too.
 OK, how did this happen?  When I looked back at the drawing I made of the original two 6-volt batteries, I noticed I correctly diagramed the red to positive, but incorrectly diagramed the black to positive too.
Nothing really happened with that setup.  The problem came when I switched out one of the batteries and hence reversed polarity.  That's when things started crackling.  I eventually got it right, but then nothing worked in the coach.  Perhaps there's some kind of safety mechanism, what I like to call idiot-proof stuff, for guys like me.

Thanks to Steve for his advice....and I thank the good Lord that I didn't need it.

John & Cheryl 1989 22' RL Big Red
[Life With A Lazy Daze RV] Re: New Batteries & Reverse Polarity
Reply #3 –
Yahoo Message Number: 56350
Quote
Nothing really happened with that setup.  The problem came when I switched out one of the batteries and hence reversed polarity.  That's when things started crackling.  I eventually got it right, but then nothing worked in the coach.  Perhaps there's some kind of safety
Aha! If the polarity was switched only on one battery, then the coach would have been getting essentially 0 Volts. So, little was damaged.
Somewhere, a current path exists local to the battery circuit which shorted the batteries together, blowing the fuse. Damage could exist in the wiring or internals of the converter, but unlikely anywhere else. I would inspect all the wiring you can see to and from the converter, and keep an eye on converter/battery-charger functions for awhile, just in case.

Steve
2004 FL
2013 Honda Fit
 
Re: New Batteries & Reverse Polarity
Reply #5 –
Yahoo Message Number: 56469
Hi Guys, I have done the battery replacement on several coaches, both gas and diesel. The smart thing to do, before you remove anything, is to take a digital picture(s); draw a physical diagram/pictorial; label all the wires and battery posts with numbers or alphabets. Mark or indicate on the digital picture, diagram/pictorial the exact same physical marks as on the real stuff. This way you can put it back the same way you tore it apart.
 Be sure to note the physical orientation of batteries before removal.
Replace them with the same orientation.
 Most technical folks say remove the negative lead that goes to the frame or ground first. Replace in same order. Put the negative lead on last. Just be careful not to short anything to ground.
 By the way, I recommend you go with either Trojan or Interstate. Don't go for the Wal-Mart or Costco alternatives. There is an old saying with batteries, "if you can't pick them up, then buy them." When it comes to batteries, you need a lot of moxy not glitter.
Regards,

Rubin --