I sounds like you need a maintainer, rather than a charger.

A maintainer is designed to keep the battery fully charged on an infrequently driven vehicle. It's designed to be plugged in and left on at all times, and has on-board circuitry to prevent over-charging.

A charger is designed to rapidly charge up a dead or low battery. It is not meant to be used continuously, but rather as a one-time event.

"Battery Tender" and "BatteryMINDer" are two popular brands of maintainers.

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1998 E300 turbodiesel

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