=================================
As posted by Bill Dube who builds and races electricaly poewered drag
motorcycles.
http://www.killacycle.com====================================
Well, I said I was going to do it and we finally got the prototype
built.
We just built a 600 cranking amp, 11.5 A-hr, battery that weighs just
3.7 pounds. I've been testing it in my GMC van for the past week here
in the Denver Winter. It snaps the van right over every morning
without a problem. The van cranks faster than it did with the
standard lead-acid battery.
It is smaller than the Odyssey 680 so it fit in the same battery box
with a couple of foam blocks for spacers.
The battery has four status LEDs that tell you the cell balancing
electronics are working OK. We are using A123 Systems M1 cells with
our own custom battery management electronics. The A123 Systems cells
are proven to be the safest Li-Ion cells on the market. No problems
with fires (like laptop cells) because the chemistry they use is
completely different.
The battery can be damaged by running it completely flat (like
leaving the master on) and holding the battery below 8 volts for a
long time. It can also be damaged by charging it over 15.0 volts. It
will likely still function after such abuse, but it won't be nearly
as good as it was originally. If you don't abuse it, it should last
you for many years.
I think we will be in production in about a month, maybe two.
Specs:
3.7 lbs
600 cranking amps
11.5 amp-hr
Approximate maximum dimensions: 3" wide, 5" long, 7" tall (including
terminals)
Charging voltage = 13.8 to 15.0 volts (anywhere in this range is OK)
Nominal voltage = 13.2 volts (Just a touch higher than your typical
lead-acid, so it spins the starter a touch faster.)
Cell cycle life rated at 2000 cycles (80% DOD, 90% capacity
remaining) 10,000 cycles (80% DOD with 50% capacity remaining) @25 C
Cell specs:
<http://www.a123systems.com/html/products/ANR26650M1specs.pdf"
http://www.a123systems.com/html/products/ANR26650M1specs.pdf>
http://www.a123systems.com/html/products/ANR26650M1specs.pdf
Maintenance free
No heavy metals (iron-phosphate type cells)
At this time, we estimate the retail price will be $595. (Yeah, I
know this is not cheap, but this is the state-of-the-art battery
technology so the parts to make it are not cheap.)
Here is a picture of the prototype. We have it in a clear Lexan case
so we can keep an eye on it. The production battery will have a
smaller opaque case with a clear top lid (terminal end.)
http://www.killacycle.com/photos/aircraft-battery/Prototype1InVan.JPGWe have been racing these cells in the KillaCycle for about a year,
so we know _all_ about them.
<http://www.KillaCycle.com"
http://www.KillaCycle.com>
http://www.KillaCycle.c
om (Be sure to
watch the movie clip.)
We figured that most folks would want a battery that had the cranking
amps to easily spin the starter and would not care much about the a-hrs.
The cost is directly proportional to the amp-hrs. If we were to go to
16 amp-hrs (it's easy to do) the cost would go up to about $850. The
cranking amps would also go up in proportion too. Figure about $1 per
cranking amp, and about $50 per amp-hr and you won't be far off. The
steps are 2.3 a-hr and 120 cranking amp increments. You pick.
This battery REALLY spins the starter in my GMC van. When I turn on
the key in the morning, the battery voltage is typically 13.4 volts
(instead of 12.8 volts.)
Anyone in the Denver area that flies daily interested in flight
testing one of these? You would get to keep the battery and write
anything you want about it (good or bad) as long as it was truthful.
You would have to inspect it before and after each flight including
noting the voltage and the BMS indicator light status. You must sign
the usual liability waiver we are all now accustomed to of course. :-)
You need to isolate it from over and under voltage as much as you
would your present sealed lead-acid battery. I would suggest a buzzer
connected to a door switch to warn you that you have left the master
on. You should also have a warning light on the panel for over and
under voltage. You should have these already.
Keep in mind that this battery will withstand over and under
voltage. It just "wounds" it much like such mistreatment "wounds"
your present sealed lead-acid battery. This battery will take the
abuse without creating an additional hazard. Other, less safe, types
of Li-Ion batteries will do very bad things (like burst into flames)
if you subject them to abuse.
You wouldn't want to use anything other than a warning
system for over and under voltage. This would cause a hazard greater
than letting the battery "take the abuse". There is no danger in
abusing the battery other than reducing its capacity for later use.
To give you an idea of how tough these batteries are, we
routinely heat these up to 100 C (212 F) in the bike. We routinely
draw 50% more than their rated current. We routinely go below the
minimum voltage (briefly.) We have accidentally over charged some of
these cells. Yet, despite this abuse, we have never had to replace a
single one of the 880 cells in the bike.
These are not the delicate Li-Ion cells that they put in
your laptop or cellphone.
Bill Dube'
bike@KillaCycle.com
