Cigarette lighter on '81; power with ignition or not?

[Canada20]

Hey all. Kind of a cryptic title, sorry about that.

I just got a solar charger to maintain the battery in my '81 (doesn't get driven very much). I assumed the lighter socket always has power to it even when the ignition is off, but is that really the case?

Many thanks,

Greg

(BTW before anyone tells me that it's easy to check by trying out the lighter, there isn't one in the truck and my Honda doesn't have one so I can't)