I do not drive my SC430 much and every few weeks when I need to drive the battery is dead. Has anyone used CTEK or other brand smart battery charger to keep battery charged in SC430 as it keeps on loosing charge?/ does anyone know if CTEK charger like US7002 would be compatible and work. tender is not an option for me because i do not have an electric outlet where car is parked.

 

The CTEK charger, US7002, is simply a charger with some good charging circuitry built in. However, you still need 110v power to use it. Wouldn't a better solution for you be a solar, trickle charger? Too, they are much less inexpensive than the CTEK. For a jump start, there are a bunch of lithium battery-based units available. I have a Costco "Type-S" unit that cost $50 on sale. Most jump start units on Amazon are in the $60-100 range, but I can't vouch for their value like I can for the Costco unit.

 

Welcome to Club Lexus. This is a common problem with our cars and well documented on CL. Do a search.
I have two of these...use them on my cars.

 

A Battery Tenders is a must for cars that are garaged and rarely used. The Tender will extend the life of a rarely used battery, closer to normal use. Cars (garage queens) should be driven periodically anyway to get the oil flowing. I have a battery tender-charger in the garage with extension cords so it is easy to swap charging cars. The daily drivers are not trickle charged. For $40 investment, can not go wrong.