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Old Feb 03, 2013, 08:28 PM
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Originally Posted by kallend View Post
Same reason as dissolving sugar in water to make sugar solution can be done faster than crystallizing solid sugar from sugar solution. Same reason that melting quartz can be done in a few seconds, but crystallizing quartz from the molten state takes months.

And in terms of speed, just think of the difference between slowly cooled steel and steel that has been quenched in cold water.
I'm having difficulty equating your examples with the chemical processes occurring in the battery.
Your analogies are appreciated for extreme simplicity but that's not what will satisfy the curiosity that prompts my questions.
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Old Feb 03, 2013, 11:22 PM
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I'm having difficulty equating your examples with the chemical processes occurring in the battery.
Your analogies are appreciated for extreme simplicity but that's not what will satisfy the curiosity that prompts my questions.

It's ALL chemistry. Chemical kinetics is just as important as chemical thermodynamics.

There is absolutely no reason to suppose that the kinetics of the electrodes during discharge are the same as the kinetics during charge. Likewise there is absolutely no reason to suppose that slow charging and fast charging led to the same morphology of the electrodes.
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Old Feb 03, 2013, 11:35 PM
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It's ALL chemistry. Chemical kinetics is just as important as chemical thermodynamics.

There is absolutely no reason to suppose that the kinetics of the electrodes during discharge are the same as the kinetics during charge. Likewise there is absolutely no reason to suppose that slow charging and fast charging led to the same morphology of the electrodes.
Well, perhaps - but what I'm looking for are more specifics. Without an explanation of the process there is only assumption and you know where that leads.

Charging rates and discharge rates are obviously associated with internal resistance. This does not explain the traditionally accepted differences between these rates though. As to you stating that the "Kinetics" are different between charge and discharge - explain why and what is actually happening.

Maybe in current (pun intended) understanding among hobbyists who tend to be pragmatic, this is grasping at something that can't be explained here. But, where does one get that type of information? I have not read of anything that broaches this topic. All that keeps coming up is that cycle life is affected by charge and discharge rates with no explanation of differences between them.
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Old Feb 04, 2013, 12:03 AM
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this is grasping at something that can't be explained here.
I believe you've hit the nail on the head.

The information that you seek is certainly available but is beyond the depth that is typically available on a forum aimed at hobbyists. University and industry research technical white papers that describe the electrochemical conversion process in detail can be found with some amount of searching.

Mark
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Old Feb 04, 2013, 09:17 AM
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Well, perhaps - but what I'm looking for are more specifics. Without an explanation of the process there is only assumption and you know where that leads.

Charging rates and discharge rates are obviously associated with internal resistance. This does not explain the traditionally accepted differences between these rates though. As to you stating that the "Kinetics" are different between charge and discharge - explain why and what is actually happening.

Maybe in current (pun intended) understanding among hobbyists who tend to be pragmatic, this is grasping at something that can't be explained here. But, where does one get that type of information? I have not read of anything that broaches this topic. All that keeps coming up is that cycle life is affected by charge and discharge rates with no explanation of differences between them.
The only assumption is that there is no effect of charge rate and that charge and discharge kinetics are the same. Without doing some detailed experiments to confirm it, there is absolutely no reason to believe that assumption based on our knowledge of the behavior of other systems.
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Old Feb 04, 2013, 09:44 PM
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This topic is also being discussed in another thread - Relationship between C rating and amps you can charge at?

I'll stop posting about it here to avoid duplication.
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