They are fused at 15 amps but it is just a flash to ignite them and that is on the direct wire from the battery.
The PnP kits that are available do not seem to have the normal wire for he flash and just run of the ballast. Now there seems to be a relay kit for those systems that have issues with flashing or only one light igniting and I think that allows the power tap in. I don't think that supplys the ability to have both low and high beam at the same time.
If these need that you are probably better off creating your own relay setup. All you need is to run one positive line in from the battery, two single throw/double pole normal off (actually you only need 1 single pole & 1 double pole) relays and some connectors to splice it all in.
I was also thinking about the battery and changing over to a Deep Discharge AGM battery. Fewer worries about maintenance and it should isolate the charging system somewhat from those surges. Again this is just a thought, I haven’t made any final decisions yet as this is unfamiliar territory.