2000 E55 battery drains after sitting for 10 days or so. Anyone use a solar battery tender plugged into the cigarette lighter socket? Will it work with the electrical system?

I'm planning some major repairs so the car will be sitting for a month.
Thanks!

Not in this car, but I had some success in my M class that was having the same problem. I did not run in through the 12 volt sockets, but went off of the ground terminal and battery post instead. The tender kept the battery going for several months and finally I just bought a new battery. haven't had a problem since.

Thanks NAFT1! When I posted the question on my screen it displayed "Related Posts"; looks like this question has been asked on other model forums. I may need to connect to the battery direct, as the cigarette lighter is not live with the key off.
. Appreciate your quick response!

Sure; good luck. FYI, I used this on the ML430 and it started up every time on the rare occasions that I used the car over about a year or so.