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| Author: | dieselenthusiast [ Sat Dec 12, 2009 9:25 pm ] |
| Post subject: | Battery heater pads |
For those who might be interested: "A fully charged battery will only produce 40% cranking power at 0°F (18°C) even if the battery is new and in good condition." http://www.lostjeeps.com/forum/phpBB3/v ... 322#534322 |
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| Author: | FreedomKJ [ Mon Dec 14, 2009 5:10 pm ] |
| Post subject: | |
0F is actually about -18C, not 18C. While a battery will provide fewer amps at 0F than it will at higher temperatures their statement about 40% less cranking power is very misleading. Cranking Amps (CA) are the numbers of amperes a lead-acid battery at 32 degrees F (0 degrees C) can deliver for 30 seconds and maintain at least 1.2 volts per cell (7.2 volts for a 12 volt battery). In other words, CA/cranking amps determine how much power you have to start your car in most climates. Since it is more difficult for a battery to deliver power when it is cold, and since the engine requires more power to turn over when it is cold, the Cold Cranking Amps (CCA) rating is defined as: The number of amperes a lead-acid battery at 0 degrees F (-17.8 degrees C) can deliver for 30 seconds and maintain at least 1.2 volts per cell (7.2 volts for a 12-volt battery). In short, your battery is already designed to provide plenty of power at 0F (-18C) Unless you live in a climate where the temperatures are so low that the electrolytic fluid in the battery may actually freeze then you're doing more harm than good by heating it as the warmer a battery is, the shorter its lifespan. How cold does it have to get for the electrolyte to freeze you ask? Try -95F for a fully charged battery, though it can be as high as 16F for a 40% charged battery (any lower than 40% charge and your battery is already damaged beyond saving). |
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