I had this very same thing happen to me. I put the battery charger directly on the batteries and they charged properly. Long story short, my converter was bad changed it out and everything is running properly.
Along this topic:
I started leaving my Axis 24.2 on shore power 24/7 right, went to start it up V-10 and the flippen chassis bat was too low fmtt, put the old trusty Craftsman charger on & brought it back to life, guess the bird has failed, wish I could simply jumper the bird so shore power charges it or just.replace the bird. ?
Please direct me to posts that have already covered this topic. Thanks so much.