battery search takes us far and wide. There are a number of interesting
possibilities, all of which must be investigated. The Internet again
proves it's value as a research tool.
hear rumors that radio control electric planes were doing amazing
things with batteries. Light batteries giving high amps for long
runs. Since R/C planes are small, their batteries are relatively
inexpensive. A number of hobbyist are experimenting with lithium
polymer batteries. Some battery suppliers are taking their feedback
and trying to give them batteries that meet their needs. Much of
this back and forth takes place online. http://www.rcgroups.com/forums/index.php
is an active place.
of the most active and responsive lithium polymer battery companies
is Kokam Engineering. The company president, JJ Hong, is an active
participant at the forum, answering questions and supporting testing.
batteries are the RC plane market leader.
directly with JJ, we learn that Kokam has EV size batteries and
would be interested in seeing them raced. The specs are impressive.
The cells are rated at the 1 C rate. The 70 amp-hr 3.7 volt nominal
cell weighs only 4.3 lbs and can deliver 350 amps continuously and
700 amps peak. The 40 amp-hr cell weighs 1.76 lbs. It is rated at
200 amp continuous and 400 amps peak.
request a 40 amp-hr and 70 amp-hr sample cell.
next step is to evaluate the batteries. To do this, we construct
a computer controlled battery charger/discharger - The Battery Evaluator.
With the Battery Evaluator, we can specify a charge algorithm and
the discharge amp rate while recording amps and volts and battery
temperature every 0.1 of a second.
full power tests results are impressive.
meet with Kokam President JJ Hong and Vice president Dr. Joon Kim.
They were excited about the possibilities of racing their batteries
and what we could all learn from the exercise. We agreed to proceed.