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LiIon Battery Efficiency 
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#1
Mar114, 06:37 AM

P: 9

Hi,
I am trying to figure out how LiIon batteries operate in regards to efficiency. I understand they have rated voltage and current etc. and to operate them at these parameters if possible. However, i'm wondering is it simply the current that has effect on their efficiency. By Efficiency I mean the amount of energy leaving the battery that get transferred to the appliance divided by the amount of energy leaving the battery. Is the energy dissipated in the battery solely due to heat dissipation? If it's operated below rated voltage what effect does this have? I also understand that LiIon operate better at higher temperatures, but does this not just mean that they operate at a higher voltage at these temperatures but aren't actually more "efficient"? Thanks for any help, trying to get my head around this! 


#2
Mar114, 07:21 AM

Mentor
P: 12,081




#3
Mar114, 07:36 AM

P: 9

Is there anyway of quantifying battery losses beyond P=[itex]I^{2}[/itex]*R? Thanks! 


#4
Mar114, 07:47 AM

Mentor
P: 12,081

LiIon Battery Efficiency
You can approximate the battery as a perfect power supply with an additional resistor in series. A larger current will lead to a larger voltage drop at this (virtual) resistor, so the output voltage goes down.
Battery loss is then given by I^{2}R = I(UU_{0}) with the zero load voltage U_{0}. 


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