What types of issues did you have with your AGM?
I'd be very hesitant to use the lithium ion battery without knowing the rest of the charging system was fully compatible.
Quite possibly nothing was wrong with the AGM. I found what in my not an electrical engineer speak was a leak to ground in my headlight. Not a direct short, but the high beam was connected to ground. It was never on a switch, but once removed from ground, my system ohm'd out properly. My headlight is a Bates 5.75" unit, and I wired it dumbass a long time ago. Kind of surprising it worked at all. None of the electronics on my bike is Norton OEM other than the rotor and stator. And there are no Norton switches on the bike.
I started the bike up and ran it for about 18 minutes with the exhaust end pointing outside the garage. Nothing got hot except the spark plugs, cylinders and exhaust, and running with the lights off I was getting a little over 12V at the battery. I didn't test the output with the lights on, but it is probably under 12V. I'll do that tomorrow. Essentially I'm barely keeping the battery charged, but making enough juice to make the Boyer happy. An LED headlight is planned.
I'm not that worried about the lithium battery with my weak single phase 2 wire alternator. I don't worry about a lot of things I should probably worry about.
By the way, I wired up the PODtronics so that I can toggle it out of the electrical path for remote charging with a lithium battery charger. Shorts are my only real concern. I need a couple more inline fuses, and I should be fine.
Old single phase alternator, PODtronics unit is a 1P-MAX, Boyer is MkIV, coils are dual output expoxy filled coil, plugs are Autolite 3924, battery is a Antigravity 401. I let the battery sit for 20 minutes after running and checked it. Voltage was 13.28. I hooked up the charger. I'll leave it on there for an hour.