Electronic – How to a Li-Ion battery maintain decent characteristics for nine years

batterieslithium ion

Turns out Opportunity Mars rover is already working for nine years. It uses Li-Ion batteries to store energy acquired from the solar panels.

In my experience Li-Ion batteries when recharged frequently have about 40% of the original capacity after having been used for three years. I haven't tested, but I expect that in nine years they would barely charge.

Yet the rover batteries seem to have enough capacity left after nine years.

How is that possible?

Best Answer

Batteries made by Yardley Lithion

Well discussed here:

Life verification of large capacity Yardney Li-Ion cells and batteries in support of NASA missions

One version 60% capacity after 3000 cycles deep discharge

Another - 25,000 cycles, 40% depth of discharge 35 min charge/discharge periods (LEO satellite simulation). Max Voltage = 3.8V/cell!

Next Generation and Domestically Produced Active Materials for Lithium-Ion Cells for Military and Aerospace Applications

Adding material from comments that increases usefulness of answer

PJC in Jan 2013 noted that majopr points from the paper cited above included

  • "the capacity fade at lower temperature is significantly decreased" (-20 degrees C).


  • " ... also to keep the rate and depth of discharge low ("battery could not support rate of discharge >C/2 at -20C when <75% charged after 1010 sols of operation"), and for long term storage to keep the batteries at 50-70% charge, not fully charged."

  • He also noted - The anode composition and surface coating may also be different from consumer batteries.