Why Does Placing a Car Battery on Concrete Drain It?

TL;DR

Contrary to popular belief, car batteries with plastic casings can be placed on concrete without draining, thanks to advancements in technology.

Transcript

James M. asks: Why does putting a car battery on cement cause it to drain when the casing is made of plastic? Shouldn't that insulate it? Contrary to very popular belief (even touted by many a mechanic), today's car batteries with their hard plastic shells will not discharge or otherwise be damaged when placed on a concrete floor. (Of course, the o... Read More

Key Insights

• 😨 Modern car batteries with plastic casings are well-insulated and do not drain on concrete surfaces.
• 🥇 Older battery designs made with glass cells or steel encasement were susceptible to damage when placed on concrete.
• 🔋 Car batteries can self-discharge over time, with rates influenced by temperature and battery age.
• ❄️ Cold weather slows down the self-discharge process, while hot weather speeds it up.
• 🤑 Lead-acid batteries have a longer lifespan when stored in cold climates compared to tropical ones.
• ❄️ Cold weather reduces a battery's cranking amp output, but it is restored once the battery warms up.
• ❄️ Extreme cold weather can freeze the water content of lead-acid batteries and crack the cell casing.

Questions & Answers

Q: Why does putting a car battery on cement cause it to drain even though the casing is made of plastic?

The myth originated from older battery designs that were susceptible to damage from moisture or concrete surfaces. However, modern car batteries with plastic casings are well-insulated and do not drain on concrete.

Q: Can a car battery discharge simply by sitting there?

Yes, car batteries can self-discharge over time due to chemical reactions occurring within the cells. This discharge rate can range from 1% to 25% per month, depending on factors such as temperature and battery age.

Q: Does cold weather increase the self-discharge rate of car batteries?

No, cold weather actually slows down the self-discharge process, while hot weather speeds it up. A lead-acid car battery stored at high temperatures also has a shorter lifespan compared to one stored in a cold climate.

Q: How does cold weather affect a car battery's cranking amp output?

Cold weather reduces a car battery's cranking amp output, making it appear drained when starting a car. However, once warmed up, the battery's cranking amps are restored, and cold storage can extend its useful lifespan.

Summary & Key Takeaways

• Car batteries with plastic casings are not damaged or drained when placed on a concrete floor due to improvements in seals and insulation materials.

• The myth originated from older batteries made with different materials, such as lead-acid in glass cells or steel encasement.

• Today's batteries may still drain due to dirt or chemical reactions, but self-discharge rates are influenced by temperature and age.