EE382C Embedded Software Systems - Battery Technology

Prof. Brian L. Evans, Dept. of Electrical and Computer Engineering, The University of Texas at Austin,

Battery technology is a key limiting factor in handheld embedded systems such as cellular phones. Below, I list volumetric and gravimetric ratings for four common battery families as of Summer of 1998. However, improvements within a given battery family do not improve dramatically. If you wanted to power a modern Pentium 233 using a kilogram (2.2 pounds) of NiMH batteries, then the battery would last for about 18 hours.

Battery	Weight	Volume	Ratio
NiCd	55 Wh/kg	145 Wh/l	0.3793 l/kg
NiMH	75 Wh/kg	210 Wh/l	0.3571 l/kg
Li Ion	110 Wh/kg	270 Wh/l	0.4074 l/kg
Zn-Air	188 Wh/kg	238 Wh/l	0.7899 l/kg

Notes:

NiMH is Nickel/metal-hydroxide.
NiCd, NiMH, and Li+ are used in cellular phones
NiMH is used in electric vehicles (see IEEE Spectrum, December 1997, page 69).
These figures were sent to me by e-mail by Larry Hayes (Larry_Hayes@latgqmg.sps.mot.com) from the Motorola Semiconductor Product Sector in Phoneix, Arizona.

Updated 01/18/00.