Ammeter pegged...

MAD's bypass has flaws too. Besides its not a fix. The ammeter is telling you something on the battery side of its circuit is drawing current big time, although not all the time. Instead of hacking up something you're not familiar, my advice is find the problem and fix it. I had 3 P-part voltage regulators fail, and a several Standard VR-128 flake out like your seeing. However, that's a different type of VR, it controls the positive side. So I don't know if your p-part VR might flake the same way or not, but I wouldn't discount it.

So far we have four possible causes we've come up with. It's probably one of them.