Friday, September 16, 2011

Why is my RV Battery Alway Dying, Bleeding Diode?

     When I first got this RV, it would constantly have a dead battery. Since getting stuck in a motor home is the last thing that I wanted to do, I immediately purchased a brand new battery. But the problem persisted. Therefore, I must have a short. In the past when I had such a problem I would put a multimeter between the power cable and the battery. If there was current passing through the multimeter with the key off, then there must be a short. I would then head for the fuse box. I would pull the fuses one at a time to isolate what area of my wiring that had the short. When the multimeter stopped showing current passing through it, I knew I had the area where the short could be found. The problem is the current never stopped passing through the multimeter. What now.

     In those days it was my practice to buy books on the problems that I was trying to solve. I would also try to speak with a dealer that sold the unit for some advise. The problem was that with an orphan motor home there was no dealer and no way of getting a wiring diagram, let alone a manual. So now what. After much effort I finally found the problem.

     The guy that owned the RV before me stored it in his back yard and treated it like a guest house. In this process he kept the batter constantly hooked up to a charger. The constant charging of the battery toasted his battery and injured the diodes in the alternator. My alternator had a bleeding diode. Diodes are designed to allow electricity to flow in only one direction. So electricity could flow out of the alternator but the diode blocked the electricity flow flowing from the charger back into the alternator. The constant pressure of the electricity against the diode has caused it to start bleeding electricity back into the alternator. This acted as a drain on the battery and caused it to die. Diodes can be replaced but I just upgraded my alternator.

     So the moral of this story is don’t keep a constant charge on your battery. This story also illustrates that solving problems with RVs can take a little special knowledge. Bleeding Alternator, who would have guessed.

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