Memory saver; power when battery disconnected

[rob_gendreau]

I've got a question about "memory savers," the dongles that go in an OBD port to provide power when the vehicle battery is disconnected.

I have to store my 2001 E250 for a bit and theft is a concern, as is the fact that I get a bit of parasitic drain on battery so it requires I trickle charge it at some point. And of course this occurs around the time I need to smog it, and so then I have to go through a bunch of driving to reset the memory so it's ready to pass CA smog.

So I'm wondering if anyone has used one? there are ways to just attach 12V to the cig lighter, although not sure if my year has some sort of cutoff there. Modern vans do. Or if there is other an advantage to power through the OBD. Or whether I should directly attach where the battery attaches. I would prefer cig lighter or OBD since there wouldn't be power to start the van.

I also have an alarm system. It won't allow a start after a battery disconnect without a code. With a battery attached via OBD I figure I could keep the alarm active.

As for a power source I could use my internal lithiums. I don't have a set up where I can get around my isolator etc, but I could easily just use the memory saver cord to connect to my house battery. The small drain from the alarm system and such wouldn't put much of a dent in the house batteries over the storage period.

Thanks for any suggestions.