I know about battery tenders. I have had one on motorcycle for years. The last battery lasted 9 years. I also have one on the running lawn mower. Batteries have lasted 5-6 years. I don't have one on the Silverado. I drive it, then I get laid up and can't drive. And it sits. I have left it sit for 4-5 weeks. So far it's always started. Sometimes it turned over hard, but always started. Then it's driven or let run for 15-30 minutes. The factory battery is 6 years old. Thinking that I may be on borrowed time.