"Roy Smith" wrote
On the wet side of the house, the modern lead-acid cell isn't much
different from a lead-acid cell from the Civil War era. The glass tank
gave way to bakelite and then to plastic, and we've got gel cells now, but
all those are minor details.
Let's see ... just since the 1970s we have gone from batteries that lasted
at best three years to batteries that routinely have a five-year warranty.
Further, I'd achieved 9+ years on a battery in my small truck ... replaced
it only because I had the opportunity (free). Current battery is 7 years old
and shows no signs of needing replacement.
The alloys used in the construction of the battery grids has changed both
the short and long term lifespan of lead acid batteries. Further, additions
to the paste, grid construction, grid alloys, and seperator construction
have lead to increased cold-crank and reserve capacities in this same
period.
Maintenance free (actually recombinant cells) that capture the gases
generated during charging, and convert them back into water have been around
about the same time ... when was the last time you checked or added water to
your car battery?
Typically put, the lead-acid battery of today has a much higher power to
weight ratio than the batteries of 30 years ago, but we tend to forget.
I'd say the lead-acid battery of today is far ahead of even 30 years ago ...
let alone when Plante first immersed two lead sheets into a mild acid
electrolyte.
In dry cells, we've gone from carbon-zinc to alkaline for primary cells
and
from NiCd to NiMH for rechargables, but again, these are incremental
improvements.
Again, NiCd cell capacity has quadrupled in the last 30 years ... 500 mA/hr
size "AA" cells were the hot ticket back in the 1970s, and today you can get
2400 mA/Hr in the same volume ( an actual 480% improvement). Yes, its an
incremental improvement ... I'd tend to call it a magnitude of order
improvement.
NiMH cells have about double the energy/lb storage capacity as NiCD cells
(you do have to remember here that we're talking about a gelled or wet-paste
electrolyte, not a flooded electrolyte NiCD cell). Again, I wouldn't call it
an incremental improvement, but again a magnitude of order improvement.
Point of fact ... can you remember when cell phones all had Lead-Acid
batteries?
Fuel cells work, but despite the occasional blather out of
Detroit and Washington, remain uneconomical for all but the most high-end
applications (i.e. space flight).
Here we are in full agreement, if only because the typical fuel cell
requires hydrogen and oxygen supplies, and it isn't practical to store
either without specialized storage and cooling. Reformer-equipped fuel cells
ARE making inroads ... in fact you can buy a reformer-equipped fuel cell
that runs off of methane (or is it butane?) to power your laptop today. It's
bigger than the laptop, but given an adequate fuel supply it's an attractive
alternative to lugging a generator around.
If you could invent a way to store electrical energy which gave a 2x
performance improvement in any of:
Energy per unit volume
Already discussed that above.
Energy per unit weight
Already discussed that above.
Manufacturing cost
Lead-acid batteries have come down in price to commodity-level priced items.
The early automobile batteries were, in some cases, rented to the auto
owner.
Useful lifetime (recharge cycles)
Here's another interesting factor ... if you plug your cell phone in every
night and recharge it (because it was run down by the end of the day), and
the battery lasted 365 cycles ... you'd be replacing the battery every year.
Many batteries are now lasting well beyond this ... some consumer batteries
are up to 700-800 cycles.
To get really large cycles (say 15,000-20,000 charge/discharge cycles), you
need only invest in nickel-hydrogen technology. Not exactly portable, since
you need a large pressure vessel for the hydrogen ... these batteries are
typically used where changing the batteries is ... uh ... difficult, say in
a geosynchronous satellite.
Environmental impact
Around 97% of the lead-acid batteries are recycled. The lead-acid battery
industry has a very tight loop ... virgin and recycled lead from the smelter
goes to the battery plant, batteries go from the plant to the consumer, old
batteries go from the consumer to the smelter. Can't get that loop any
tighter without eliminating the customer from the loop! NiCD and NiMH are
more difficult to recycle, and work continues on that front (because there
IS a lot of money in recycling these items). Most batteries escape the
recycle loop through ignorance, rather than difficulty in finding an entry
port to the recycle stream.
while holding the line on all the other factors, you would become a very
rich man in short order.
Probably not. The profit margin is paper-thin on commodity items ... if we
can make $.01 per battery made here, someone willing to work for less
overhead will allow that manufacturer to make a bit more profit. This means
the other manufacturer can/will drop prices to the point where on-shore
manufacturing goes broke. No ... the money is made by recycling, because
EVERYONE needs batteries, and ALL the manufacturers need raw (virgin or
recycled) materials to make more.
*****
Perhaps batteries suck ... I think our memory is faulty. I've had
rechargable batteries in electronics and in tools for about 30 years now,
and I find myself getting upset over the lifespan, until I recalibrate.
Energy efficiency in our equipment that uses batteries is where we need to
make a big improvement. Face it ... cell phones of even 10 years ago hogged
power ... but all they did was send and receive phone calls. As the
technology improved, the actual "telephone" current requirement dropped ...
but the marketplace demanded "toys" in addition to their telephone. Current
consumption has gone up ... in some cases as fast as battery capacity.
Regards,
Rick
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