Lee Hart wrote:
...most lithiums are shot in 3-5 years.
David Nelson wrote:
To be fair, how those batteries were treated needs to be factored in.
Absolutely! How they are treated makes a tremendous difference. The life
expectancy of any battery, or any type is mainly determined by what you
do WRONG to it. Most batteries don't die of old age -- they are murdered
by ignorance and abuse!
...the specs might not actually be correct for long battery life.
Right. The manufacturer is interested in profit. He'd rather not do
lengthy expensive tests. No one is checking his claims. It's easier to
make up the data.
...many packs are overcharged and undersized.
Yes. Even if you get the charger from the manufacturer, their interest
is in maximizing sales, not life. Some of the worst chargers are the
ones that come with the products.
Undersizing the pack is an easy way to save money; so everyone does it.
I went with a 200Ah pack in my Gizmo. The max current my controller
can pull is still only 2.5C which is under the rating of my 11/2009
TS cells.
That is a good strategy for any battery technology; not just lithium. In
general, don't run things at their maximum ratings if you want long life!
BTW, no balancing since 7/2011 and still no measurable drift between
cells.
That's good to hear. Balancing all depends on how well balanced your
cells are to begin with, and how hard they get used/abused. It sounds
like you were lucky enough to get well-matched cells to begin with. And
your pattern of use is easy on them; no high currents, high
temperatures, deep discharges, or overcharging. That will keep any
differences between cells from growing.
Just keep watching for imbalances. As the cells age, the differences
will inevitably grow. At some point, I think balancing will become
necessary. Without it, a cell that starts drifting out of balance will
not get corrected.
--
Humanity is acquiring all the right technology for all the wrong
reasons. -- R. Buckminster Fuller
--
Lee A. Hart, http://www.sunrise-ev.com/LeesEVs.htm
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