Properly Maintaining an Old Car Battery

Neglect is probably the No. 1 Cause of your Benz not starting

I see too many neglected batteries - especially on old cars - and especially on old cars that do not get driven often. A friend recently emailed me with much chagrin that his 240D would not crank over fast enough to start the engine. He just couldn't understand it. He knew he had a good Optima battery and had recently replaced his voltage regulator. I always teach - check the simple things first - and fired back an email that he should check his battery post connections. He thought they looked ok, but upon removing the battery terminals he saw the dreaded white power. After cleaning the posts and using battery terminal protector he was quickly back in business. 

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Problem & Solution

Common among these chassis:

Classic Sedans
W108 W109
W110 W111 W112 Sedan
W111 W112 Coupe

Here are some recommendations to keep you battery in tip top shape:

1. Don't let the battery drain down completely. When you allow this to happen repeatedly, you will shorten the life of the battery. If you have a car that does not get driven very often, use a trickle charger on the battery or install a quick disconnect. Something as simple as a clock can drain the battery down over time. Even if you leave a lead acid battery disconnected you should put a charge on it at least once a month. If you install an Optima battery you may only need to put a charge on it every 3 to 4 months. If your collector car only gets driven on fair weather days the Optima battery is the only way to go!

Here are two types of battery quick disconnects you could install. They are available at most auto parts stores:

2. Clean your battery posts and cable ends yearly. Talk about neglected maintenance!  How often have you seen this and come on admit it.....and just ignored it and thought you would get to it later. At the first sign of white powder remove the cable clamp and clean it and the corresponding post with a brush made specifically for cleaning battery terminals.

3. Use battery maintenance products to prevent or slow down further corrosion. These products are also readily available at any auto parts store or store that has a large automotive section. The first are felt washers that go under the battery post clamps. These are impregnated with a special chemical that neutralizes the gases around the post that are the true gremlin. The second product is a spray can battery terminal protectant. Use this to spray on the tops of the battery terminals after you have clean and tightened them on the post.


One final tip for you diesel owners: Diesels are very hard on batteries.  Don't try to run the battery to its full warranty period. Replace it a year early.  In other words if it is a five year battery replace it at the end of four years. The added reliability and peace of mind is worth far more than the few dollars you will lose by replacing the battery early. 

Take care of your battery and it will take care of you!