This is a must have if you have a prized Benz or any car you don't drive often!! If you let any of your cars sit for long periods without driving them you can ruin your battery. Especially if you let it go completely dead. This is especially true on cheaper lead acid batteries (like Walmart). Their batteries can just not survive a few repeated deep discharges. If you have a collector car or multiple cars that you can not drive all the time the best ways to save your battery is to use a small battery float charger. Kent uses a float charger over the winter on his personal 1959 220SE as shown in the picture below.
These draw very little house current and will only put a very low amp charge into the battery. These chargers WILL NOT WORK to charge dead batteries and they will not save a battery that has already been damaged. You can hook the clamps directly to the battery posts as shown below or Kent includes a couple of terminal ends so you can safely attach the charger permanently to battery of your prize Benz if you should so choose. Use to save your battery! Keeps battery charged during long storage.