RamTC is right.
I would think your AF is wired similar to our 990s. The slide runs to the battery through it's own circuit breaker. If you measure the battery and don't see a higher voltage when you plug the AC in you have a circuit breaker open between the battery and the fuse box or the disconnect is open. You did remember to turn it on, right??
My 990 is wired with the positive side of the battery as follows:
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The Main 30A breaker, Slide 30A breaker, battery disconnect, and HappiJac 40A breaker are under the sink. The Main 40A breaker to the fuse box is under the step.
And before everyone jumps me about the 30A breaker at the battery, I've triple checked and it is a 30A. That's the way it was wired when I got it and it works so I haven't changed it. If you aren't into electronics, what I'm saying is that I suspect the 40A breaker on the HappiJacs is swapped with the 30A breaker at the battery. That will limit current to and from the battery to 30A.
It ain't broke, I ain't fixin it.
The remark about the disconnect is from experience. Several experiences.
Good luck with the trouble shooting.