While we have all the NimH experts gathered ... .

Has anyone got figures for NimH energy recovery efficiency?
This is not something that is much reported on or even cared about usually.

"Current recovery efficiency" is reasonably good - you typically charge to 
110% of rate mAh - although higher and much higher figures are suggested by 
some.
But energy recovery =  Sum/(Vout.Iout.dT) / Sum(Vin.Iin.dT) is another 
matter.
This will vary with brand and load and cell body sizeand capacity, 
temperaure,  and ....

For AA NimH Vout_average is around 1.2V at loads << C and about 1.1V at 
loads approaching C.

Vin varies with internal impedance, state of charge, charge rate, brand ...
Charging even < C/5 near full capacity gives Vin around  1.4 - 1.5 V for AA 
cells.

That suggests efficincies of around (1.2V) / ( 1.5 x 110%/100) = ~~ 70% at 
end of charge for light loads and higher at earlier stages of charge.

But nobody seems to publish the nice curves sets you see for other battery 
parameters.

Any thoughts?


            Russell 

-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist