I owned a GMC Denali and now have a 2021 RAM with Hemi V8 eTorque and own two Battery Tenders which have worked flawlessly for years. Both vehicles, if left garaged for 5 days or more would experience battery drain, prohibiting starting them. As a result, not wanting to risk overcharging, believing “simple is best” I use this model available at Amazon for $52.86:I received my truck earlier than expected and had to leave on a month long vacation a week after receiving it. Having read about the Rams electrical fussiness, I installed a Battery Tender brand battery maintainer. Having multiple vehicles and not driving some for extended periods I've been using them on other vehicles for years.
Even the manual says iif the truck will not be started for a while to disconnect the battery. I find it easier to plug it in.
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Battery Tender Plus Charger and Maintainer: Automatic 12V Powersports Battery Charger and Maintainer for Motorcycle, ATVs, and More - 12 Volt, 1.25 Amp Battery Chargers - 022-0185G-DL-WH