The SAE defines the ampacity value to be derived by a formula based on the 1 ms full cycle (of the 1 kHz signal) with the maximum continuous ampere rating being 0.6 A per 10 µs up to 850 µs (with the lowest 100 µs × 0.6 A = 6 A).
I imagine 90-100VAC is the minumum if it combines L1 and L2 in a single unit, but dropping the voltage on the fly is probably even more difficult.
I think a buffer battery like was suggested earlier is a much more straightforward path that is guaranteed to work, as opposed to trying to fish out support for corner cases out of the spec. I'd go with a normal MPPT charge controller, 6-8kWh battery (LFP or possibly LTO) and a battery inverter with load shedding.
Just the math alone should put it at 3A I guess. But given it's outside of the range established by the standard, the results can be unpredictable - charger could respect that, ignore it and stick to known min of 6A, treat it as a failure condition or... crank it out to the max because the guy who wrote the firmware left a bug in there!
A forum community dedicated to DIY electric car owners and enthusiasts. Come join the discussion about electric vehicle conversions, builds, performance, modifications, classifieds, troubleshooting, maintenance, and more!