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Old 07-11-2014, 07:42 AM   #8 (permalink)
oldtamiyaphile
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Quote:
Originally Posted by redpoint5 View Post
I'm curious if a lead acid battery dissipates energy even though it is already at full charge. If it does, I wonder how that compares to a LiFePO4 battery considering lithium chemistries require current flow to cease when full charge is reached.
Once LA batteries approach full charge their charge acceptance begins to drop. Modern "smart' alternators look for this drop in charge acceptance to determine the level of charge in the battery (when the alt. is running voltage is pretty much a constant 13.8v regardless of battery charge).

I do believe the excess current can only become heat, much like when you bench charge a LiFe and it gets warm as it gets full.

How would you quantify it? It seems more like something to do on a bench than in an engine bay, which would give you far greater control over variables. You could possibly spin up an alternator with a power drill, and add load via lights or 12v motors.
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