Originally Posted by S101
I have a 2004 Forest River Lexington 235s with a Ford E-450 chassis. I had the rv in for work for a propane leak and had them check the refrigerator to make sure propane operations were good (only had rv 3 months and never tried it). RV was ready for a week before I called (long story). When I picked it up they said they had to jump it and the coach batteries were dead. I suspect they left the refrigerator on for the 8 days before I picked it up. But when home:
1. Would not start next day. Chassis battery low.
2. I put a battery charger / conditioner on one of the two coach batteries figuring it would charge both. It did.
3. Went to check chassis battery for possible drain. When I checked the meter by measuring battery voltage it was back to 13. I have to conclude it was charged overnight along with the coach batteries.
4. I found .03 volt drain on chassis battery. But remembered shore power was connected to coach. I disconnected that and got 0 drain.
So, I’m confused. Expected that other than alternator charging and engaging coach batteries via switch on dash to start if needed they were separate systems.
I can only assume that whatever drained the coach batteries also impacted the chassis battery.
Does this make any sense?
Welcome to the forum.
If these are original batteries, they are old enough they may be doing excessive "self-draining". In a case like that, they could easily go dead in a short time all by themselves. Even brand new lead acid batteries slowly self-discharge, but it generally gets worse as they age. It would probably pay to get them checked. It takes a simple portable load machine about the size of a portable charger. Automotive stores may do it for free since they hope to sell us the new ones.
This battery trouble isn't unusual in RVs since they are more likely to not be driven daily and owners aren't very diligent in keeping them plugged in right away, including me. I usually think I'm going to drive them sooner than I actually do. Lead acid batteries permanently deteriorate faster when in a slightly discharged state and provide the longest service if kept fully charged, or at least up to 13.5 volts or so. Going completely dead, even one time, takes a big chunk of overall life out of them, so it is to be avoided if at all possible.
I've used simple, but reliable, Harbor Freight float chargers for years on several vehicles, boats and bikes. A float charger is made to maintain the charge at about 13.5v rather than charge a dead battery, but they slowly will at about one amp. These only cost about $5 if on sale and are much smaller than the size of my laptop supply. I leave the batteries installed over winter and just peek once in a while to make sure they have power yet. Full size batteries won't run out of water, except very small motorcycle batteries which may get low over six months.
As an example, I had a 1994 pick-up that I knew I wouldn't drive much and was pretty good about hooking the HF charger up right away when I parked it. The original battery lasted for 15 years and was still working when I put a new one in. I did note that the cranking began to slow quickly in our frigid ND winter and didn't want to take any chances. It never quit me though. The truck always started.
So what you suspected is probably true. All the batteries suffered the same fate... they were old.