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The internet gives lots of contradicting advise about greasing or not greasing car battery posts to prevent corrosion. So rather than rely on the internet, I want to perform an experiment so that I can prove to myself that grease is good (or bad).

I want to measure the difference in current/voltage/power when I start the car with clean vs greased posts, (high current).

I also want to measure the difference between clean and greased posts when I charge the car battery, (low current).

My hypothesis is that dielectric grease does not add resistance. I expect that when contacts dripping with gobs of grease come together, the grease will be squeezed out of the space between the conductors, and whatever residue that remains between the contacts will not interfere with the current. But I want to test my hypothesis experimentally.

These are the materials I have available for the experiment: household items, ordinary garage tools, a cheap digital multimeter that I don't know how to use, wires with gator clips, copper wires of various size from magnet wire to 10 AWG.

Please describe a simple and safe experiment setup and make a prediction about what the outcome will be. Thanks.

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For the experiment you can use a cup with water and sodium bicarbonate or baking powder to reduce the resistance of the water, then tune the multimeter to voltage and connect each side to the battery points. It will read for example 12 volts, then connect the posts and put the cables in the water the voltage should drop for example 12 to 5 that is a drop of 7. Do the same with grease only in the posts and if the drop is the same there is no problem but if the voltage drops less it means the grease have more resistance. i think the grease reduces the conductive area of the post and reduces the resistance but that reduction is very small and it shouldnt affect anything

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