Actually that won't make much difference, AC is generally considered more dangerous than DC, at least as far as humans are concerned, I don't know about rats. Most electrical safety codes agree, they IEE regulations state that the highest voltage allowed on uninsulated wires in dry conditions is 60VDC or 25VAC, even though 60VDC is higher than the peak voltage of 25VAC.
Anyway, the only solution is to stop feeding the rats.
I have a feeling that the squirel feeder spills some of the food on to the ground, perhaps you could put a plastic sheet underneath it and clean up the spillage before nightfall.
The best solution -- four or five cats, or even better, Yorkies. They'll keep the rats away. I had a problem with rats when I lived in the Washington DC area. First, I love dogs, secondly, I love Yorkies. I wound up living with four Yorkies. Those Yorkies were perfect ratters. They killed quite a number, and once the rats knew that there were dogs about, they disappeared.
The thread looks tongue in cheek, it is amusing to joke about things like this, but not do them.
Made me think about fox hunting, which is a ritual here in the UK, they dress up in costume and chase the fox on horse with a pack of hounds. The morality of this is debated endlessly and in one conversation in the houses of parliament one member called the fox a pest no better than a rat. The reply came 'would you dress up in costume, get on a horse and chase a rat'. Made me laugh anyway...personally I like rats.
In Pacific islands, they use a band of sheet metal around the truck of palm tree to block the rats from getting to the coconuts. Ships use cones on tie ropes to keep rats from climing up the moorring ropes onto the ship.