Avionics News March 2015 - 19

True Blue Power's TB44 (left) and TB17

Expect others to follow Concorde's lead after
last year's introduction of True Blue Power
batteries, employing lithium-ion chemistries
less-hostile, less-costly and more-attractive
solutions for main-ship electrical systems.
Still, Nirvana remains elusive. Other
forms of lead-acid batteries still dominate
general aviation. And old-technology
flooded-cell batteries remain relatively
cheap and available - and known.
You may need that old hydrometer to
check them, so don't toss it just yet. But
consider the alternatives already tried as
aviation sought alternatives to all dominant
lead-acid styles - types already not compatible
with a hydrometer check.
Advancing into the future
After a number of flirtations with alternative technologies,
lead-acid - and a couple of those transient technologies -
continued to face eventual obsolescence with everyone from
battery manufacturers to airframe makers to aircraft owners
and operators.
The most-meaningful challenge to the dominant leadacid technology were nickel-cadmium batteries. Costly,
temperature and charging sensitive, these batteries have
enjoyed a good run in, primarily, turbine-aircraft applications.
Meanwhile, in the piston world, the biggest leap came in
the form of the valve-regulated lead-acid battery - VRLA.
Best known as recombinant-gas batteries, they exist in two
forms: gel cells and absorbed glass-mat batteries. The former
styles use silica powder mixed into the electrolyte, rendering
it into a gelatin-like state; AGM batteries employ a fiberglass
mat between the plates. Both benefit from their greatly
reduced maintenance; no fluid checking since they're sealed.
And both can, in general, be mounted at any attitude.
Both gel and the mat help stabilize the lead plates,
contributing to longer life and the ability to use thinner and
more plates to boost capacity. While both initially cost more
upfront, over time and as their prices have declined, they've
become more than competitive with the older technology
thanks to both reduced maintenance and longer life.
With aviation's progression to electronic panels, demands
on electrical systems helped drive planemakers to bolster their

electrical systems, and high-capacity batteries would almost
always be welcome. Welcome, within the weight and balance
limitations of the aircraft, of course.
NiCads, while attractive when no alternatives existed,
suffer from "memory" problems that reduce their ability to
take a charge and didn't deliver the power desired.
Nickel-metal hydride batteries held promise thwarted in
larger part by their manufacturing costs - and limitations in
power density potential similar to NiCads.
The greatest promise so far came via another revolution in
battery chemistry: lithium-ion.
The portable electronics catalyst
The advent 30 years ago of cellphones and portable
computers challenged battery designers to produce higher
power densities while eliminating some problems with
existing battery technology. The NmH and NiCad alternatives
weren't satisfying the increasing demands for compact
packing with high-power density.
The latest marketable answer came from lithium-ion
technologies. And we say "technologies" because multiple
chemical and structural iterations exist based on the metal
lithium.
Continued on following page
avionics news

march

2015

Avionics News March 2015

Table of Contents for the Digital Edition of Avionics News March 2015