Originally Posted by jamoke
Not sure where you got your info about losing presets.
The presets are maintained by a standard replaceable lithium cell when the unit is unplugged. Without the small coin-size battery, the presets would be lost.
Link to manual (See page 8)
Good luck in your search.
I got the info from some customer reviews. A few buyers who said they would have liked the unit if that were not the case. The only thing I can think of is they have very recently changed it as two reviewers specifically mentioned losing the presets when unplugging being an issue. Even if they will stay if you keep batteries in is not a good option for me either as I would store in my camper, and would worry about battery corrosion and not really keen on taking them out and back in every trip.
Here is a link to the review page where I saw two users mention the preset issue. If an internal lithium battery would prevent this, can't imagine why they are mentioning it? Unless perhaps this is a new addition to the unit based on customer return feedback.
Maybe the lithium battery is not included and they never put one in. Not sure.
Thanks for your reply!