On the short drive home (about 1 mile) the voltage went up to about 12.4v while the engine was running (as the chassis alternator was trying to give them some charge). When I got home I plugged the RV in to shore power so the converter can give it a charge overnight.
After about 5 hours of being plugged in, the voltage on the batteries is at 11.7v. Seems like it has been there a while. Is this common/expected?
No... Seems the wfco is not charging. You should be up over 11.7 because the truck was charging @12.4. And yes the wfco fan would come on non stop at that low level.
Possibly the breaker/fuse on the frame rail is blown? Need more info.
You need to do some testing on the wfco. Ill post a link, but in mean time get those batts on an external charger ASAP.
http://wfcoelectronics.com/wp-content/uploads/2015/11/New-Flow-Chart-for-WF-8900-Series.pdf
