Lead-acid was the least expensive choice for electric vehicles in the
past one hundred years.
Lead-acid batteries are no longer the best choice for electric
propulsion. Battery technology continues to improve. Although
electric vehicles generally are thought of as much more energy efficient
than gasoline powered vehicles. Batteries have been a barrier to high energy efficiency. In the past, batteries
only stored 25% of their theoretical value. Now they have improved
to 75% and more. The rest of an electric drive train is highly efficient. Both
motors and voltage controllers are in the 90-95% efficient range. By contrast
a gasoline fueled internal combustion engine is only 20-30% efficient
and a diesel engine is 30-40%.
All battery technology continues to improve as does the safety of
the lead acid batteries. The sealed lead acid gel cell battery is filled
with a gel rather than a liquid and it is not meant to be serviced
by the user. Similarly, a "sealed" battery is filled with water and then
closed so no water escapes during recharging and no water is added at
any time. It isn't really sealed however. Valves on the cells allow
gas to escape if the battery is overcharged. The gas cannot be replaced
and that cell remains weak for the rest of its life. Both of these types of batteries have a tendency to dry up. Gas produced inside the battery during charging can shear the material, causing higher internal resistance.
flooded lead-acid batteries are
truly "deep cycle". Unlike the high peak discharge of the sealed
starting batteries and gel cell lead acid batteries. The flooded deep cycle batteries have a long flat discharge curve and are designed
to discharge to lower volts without permanent long term damage and
shortening cycle life.
A battery's long term durability depends equally on two attributes. How it is built and how it is treated. The physical design
chemical materials will have a great deal of effect on the product's long-term performance.
Equally important, however
is how the battery is used and maintained during its useful life.
All batteries will last longer if it is not discharged
fully between charges. Careful recharging and the using a charging
system design for the battery chemistry used will also extend battery life.
Electric vehicle batteries now come in many chemical and cell volt packages.
Cell voltage and chemistry should be the same when creating high volt
battery packs. As we try to build high voltage battery systems in the
hundreds of volts from two and three volt cells we are putting the cells
in series one after another to create the higher voltage.
cells are not created equal and this holds true to any chemistry or
manufacture. During the life cycles the cells get weaker at different
rates and the series is only as good as its weakest link or cell. As our
technology has become better and our concern for more life cycles from
our batteries. We are now using battery management systems to balance
the strong and weak cells to optimize their power and life cycles.
It has been over ten years since Chevron Texaco bought the patents
for the large format Nickel Hydride batteries. They sued Panasonic and
stopped Toyota from producing electric powered cars using this
advanced battery technology. The cars Toyota did produce are still
running with over 100,000 miles on their
batteries. All manufactures building hybrids us the smaller
spiral nickel hydride batteries. This shows the quality and cost
effectiveness of this chemistry.
Lithium technology has arrived from China and we have seen a new
interest in the electric vehicle market. China is doing a great job
manufacturing and improving the technology.
The weight of lead acid batteries has always been the disadvantage to
bringing additional range to electric vehicle concepts. Lithium
batteries with the same energy density weigh less than 20% that of the
lead acid battery. With the life cycles of lead batteries under 500 and
the life cycles of lithium over 2000. The lithium batteries do not expel
explosive hydrogen gasses and they are not filled with corrosive acid in
unsealed cases as is true with lead batteries. These are the reasons E-V
Concepts has stopped using lead acid batteries in all its battery
propulsion conversions and new custom built vehicles.
@ e-vconcepts .com