[Tiny-tux] Meeting notes, Thu 24 Feb 2011

Corey McGuire coreyfro at coreyfro.com
Fri Feb 25 18:10:06 PST 2011


Most people shorten them to LiFe or refer to the as A123 cells, but that's
just one brand that produces them.

These are a Lithium Ion chemistry battery.

On e-bay, fresh cells, direct from china, are $2 to $3.

The A123 18650 are 1100mah, which is slightly better energy density than
NiMH.  The advantage is the relatively easy charge cycle of Lithium Ion
batteries, which has an easy to detect peak.  The batteries, unlike other
Lithium Ion batteries, have a peak of 3.7v as opposed to 4.2v and a nominal
voltage of 3.3v vs. 3.7v.

Another advantage is, unlike other lithium ion batteries, which degrade in
capacity between 10% and 20% a year, these degrade between 3% & 5% a year.
This makes them attractive for long term uses as a 5 year only LiFe battery
will have a greater capacity than an otherwise more energy dense LiPo
battery of the same age.

Though they are fairly robust, they still benefit from a Lithium Ion charge
circuit, however, they need a charge circuit that is configured for their
voltages, which may make them slightly less attractive.

On Fri, Feb 25, 2011 at 10:45 AM, Wladyslaw Zbikowski <
embeddedlinuxguy at gmail.com> wrote:

> On Fri, Feb 25, 2011 at 12:03 AM, Wladyslaw Zbikowski
> <embeddedlinuxguy at gmail.com> wrote:
> > Corey has a source for LiFe (Lithium Ion Phosphate) cylinder cells for
> about $3.
>
> Correction, this should be Lithium IRON Phosphate (LiFePO4).
>
> https://secure.wikimedia.org/wikipedia/en/wiki/Lithium_iron_phosphate
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