I don't know the construction and design of these modules but if the programming is stored in EEPROMs then yes, a good deal more power during programming than normal operation.

 

Yes, programming often does go through multiple cycles and autonomous control of various functions of the vehicle and the read/wrote times can be very long for some, more 30 minutes and longer, fans lights and more running with the generator switched off depletes the battery quickly. This isn't unique to Jaguar either.

 

Although eeproms require more power during programming they are very low power and would not account for the need for a 50A PSU.

 

Since the SDD power supply requirement for my 2007 is 25A (minimum), I bought a 30A supply.
When I first started just poking around, I figured it wasn’t going to take much juice, so I connected the supply to my battery maintainer leads, which should be able to handle 15A. Wasn’t long before the battery indicator on SDD dropped to ‘red’, so I knew it wouldn’t be sufficient to handle programming later. I got some cheap jumper cables to connect to the positive post behind the right hand panel in the trunk/boot, and a chassis ground. The thicker wire allowed enough juice to flow to keep SDD happy with the battery indicator staying green. Lots of stuff stays active in the car when SDD is running.

 

I haven't used it in battery support mode yet but I'm happy with my new purchase so far. It has essentially the same features as a CTEK (although obviously not as compact!). The supplied cables aren't heavy-duty enough but I can replace them.

 

While using SDD and my CHARGER, the amp draw is usually about 30-34 amps. That's a bit, but there also a LOT of modules and such. All running.