Sudden Coach Battery Failure

[gksmith]

I was recently surprised by sudden complete failure of both of my coach batteries! I have not used my 2003 LT Van this summer, as I had it for sale due to my purchase of a new Panoramic Van. I have been showing it periodically this summer, but have been traveling quite a bit in our new van. Hence, I have been gone for periods of time between showings. I am quite sure that earlier this summer my 12volt system was operating properly after sitting over winter. However, a couple of weeks ago, I noticed that the 12 volt lights would not turn on. I did not think too much about it and connected the van to shore power. I was in a rush for my next trip, so I did not do any further testing, and disconnected the shore power. But, a few days later, when showing it to another potential customer, I still did not have 12volt power in the coach, so I reconnected to shore power. Yesterday, I disconnected the shore power and found that I STILL do not have 12volt power when disconnected from the shore power. So, I tested my batteries, and they were badly discharged, but still showed low but some voltage. I checked the electrolyte levesl, which were fine. So, I put my farily late model baterry charger on the batteries and it subsequently showed "Battery Failure" on both disconnected batteries! Going through the repair mode on the chrager does not seem to help. So, I fear they are toast!

So, my question is, "Could something in the 12 volt system cause simultaneous complete battery failure?" I know that completely discharging lead acid batteries is bad for the batteries, and I admit that this is unfortuntately not the first time they have been abused by too much discharge, but I have never had complete battery failure! I do have a late model power convernter in the coach, so I believe they were properly recharged (if that is possible) while on shore power. I do not want to put new coach batteries in the unit and have them prematurely fail if it seems that there might be something wrong in my 12volt system other than possbile battery abuse and possible accidental deep battery drainage between showings.

Any comments or suggestions? Any testing I can do? Thanks in advance!