Battery Experts! Inside please.

Max Power said:

Again Hack, I live in the Twin Cities. I know the weather here.

The reason batteries suffer in the cold is that loads increase exponentially with decrease in temperature. The battery is cranking just fine, but the engine requires something like 400% more current at 20 below than it does at 20 above.

Also, heat that kills a battery doesn't just come from ambient outdoor tempurature. It comes from the design of your engine bay, and the spacing of the plates in the battery. That why you don't see 1000cca batteries in 24f cases anymore. They all got warrantied in less than two years cuz the batteries were so crammed full of plates that they couldn't cool.

The cement floor thing is a myth.

Click to expand...

Ozsum2 said:

I always heard and thought that a cold engine was hard to start because the oil was thicker, nothing to do with the engine itself. And when it is cold outside, the battery looses something like 30 to 60% of its CCA, so how can a battery be cranking just fine if it is below optimun CCA?

Click to expand...

Max Power said:

hack your point contradicts itself. If a battery cant flow as much when cold, why would it discharge quicker when cold? That doesn't make sense. The reason the battery has a harder time starting the car after 8 hours in the cold is because it is trying to start a cold car, not because it discharged quicker.

Yes, batteries have less cranking power when cold, but still have plenty to turn the engine over. The rule used to be 1cc per cubic inch displacement. Most batteries have 600-650cca, so there is more than enough cranking power.

Oz, you are correct, the fliuds become a huge drag as temps dip, not the engine. Not only is the oil a lot thicker, but with automatic cars, you have to turn all that fluid in the converter. Also, electrical circuits offer more resistence when cold, if I am not mistaken, so the starter and cables would offer more drag.

Click to expand...

Max Power said:

A battery will not discharge faster in the cold, but it's cranking amps will reduce. Current flow slower in cold weather, which is why starters and electrical systems create an increased drag.

I looked on my battery last night as I was trying to fire up my new 393, and it said at 32F it had 625cca, and at 0f it had 550 CCA. That is a reduction in cranking amps of about 20%, so I imagine at 20 below, the cca would be reduced by another 20% or so.

Even battery mfgs for little batteries like Duracells recommend storing your batteries in a cool dry place, like your refrigerator.

This is what they tought me in trade school, what they tought me for my certification tests, and what ten years sellings batteries for Johnson Controls taught me.

While that is not empirical evidence, for me, it's the way to bet!

BTW, try turning a motor over by hand when it is cold vs warm. You will get the idea.

Click to expand...

Max Power said:

A battery will not discharge faster in the cold, but it's cranking amps will reduce. Current flow slower in cold weather, which is why starters and electrical systems create an increased drag.

I looked on my battery last night as I was trying to fire up my new 393, and it said at 32F it had 625cca, and at 0f it had 550 CCA. That is a reduction in cranking amps of about 20%, so I imagine at 20 below, the cca would be reduced by another 20% or so.

Even battery mfgs for little batteries like Duracells recommend storing your batteries in a cool dry place, like your refrigerator.

This is what they tought me in trade school, what they tought me for my certification tests, and what ten years sellings batteries for Johnson Controls taught me.

While that is not empirical evidence, for me, it's the way to bet!

BTW, try turning a motor over by hand when it is cold vs warm. You will get the idea.

Click to expand...