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Old 06-09-2013, 06:33 AM   #560
_cy_ OP
Beastly Adventurer
 
Joined: Sep 2011
Location: Tulsa, Oklahoma
Oddometer: 5,897
Quote:
Originally Posted by plodalong View Post
Can't remember exactly what the temp was, but not hot or cold so probably around 20c (70f)
reason why temperature was requested is LiFePo4 batteries perform quite differently at colder temps. at 14f loses 1/2 it's AH capacities. peak numbers while impressive are not as important as what LiFePO4 battery can deliver continuously under load.

all lithium batteries share trait of low internal resistance which results in high discharge rates disproportional to size of battery. leading to outrageous amp hour equivalent to lead acid capacity claims (PB/EQ).

All 12v LiFePO4 batteries uses four cells in series. if cylindrical 26650 A123 type batteries are used. capacity for each series are 2.3AH for old style or 2.5AH for new. then further series are added in parallel to increase AH capacities. LiFePO4 batteries using 8 cells = 4.6AH actual

here's a video done by Joel W who's one of the sharpest techs on ADV. illustrates how a Shorai LFX18 successfully performs multiple short duration cranks, while sustaining a brutal discharge load in between cranks. but Shorai LFX18 will not survive even a single 200amp continuous load test.

so if one is starting a modern bike in good tune at warm temps always taking off from a garage. AH capacities needed to support that bike are smaller than someone riding their adventure motorcycle in cold temps far from any support.

one of the most common reason resulting in LiFePO4 failures in our motorcycles is under sizing LiFePO4 batteries. resulting from not understanding importance of factoring in how and under what conditions that motorcycle will be used.


_cy_ screwed with this post 06-09-2013 at 06:59 AM
_cy_ is offline   Reply With Quote