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| Frequently
Asked RC Car Battery Questions |
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What
makes matched cells so special?
When the cells are delivered to the matching company,
like Pro-Match
Racing or Team
Orion they are "matched" (a process
by which they are charged and discharged "cycled")
Cycling measures the performance parameters of each
cell. For information on performance parameters
see our page on battery labels. The cells are then
grouped into categories like world spec, sport,
team, xtreme , factory team. The cells with the
lowest numbers go into the spec, sport, or stick
packs. The higher numbers go into the team, xtreme,
or factory team packs.
This information was taken from the Pro-Match
racing site which I helped design in April of 2003.
I also designed the label that Pro-Match currently
uses on all of their matched batteries.
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Run
Time - Amount of time it takes to
discharge the cell to the discharge cutoff voltage.
Run time is important, as it tells you how long the
cell will last when discharged at the discharge current
to the discharge cutoff voltage. Run time is most
important to people who drive modified on oval tracks.
Divide this number by 60 to figure out about how many
minutes the pack will last under race condition. NOTE:
Make sure when comparing cells that they have the
same discharge rate. The Run Time on a pack discharged
at 30 amps will be lower that the Run Time on a pack
discharged at 20 amps. See the Pro-Match Racing conversion
chart for more details.
Charge Rate
- Amperage rate the cell is charged at. The charge
rate is a determining factor in the internal resistance
reading . The higher the amperage the cell is charged
at the higher the relative internal resistance number
will be on the label.
Discharge Rate
- Amperage load used to discharge the cell. The discharge
cutoff voltage standards are .85-.90 volts for 30
amp and .90 for 20 and 25 amp cells. This is the voltage
at which the discharge process ends. Lowering this
cutoff point will extend run time results and lower
the average voltage reading. Raising this point will
shorten run time but raise the average voltage reading.
Discharge Cutoff Voltage
- Voltage level used to stop the voltage averaging.
Average voltage - The average voltage level throughout
the discharge process. The average voltage is calculated
by sampling the voltage 10 times per second, starting
at the peak voltage and terminating the sampling when
either the discharge cutoff voltage is reached, or
when the discharge time has expired. It is possible
to 'fudge' the average voltage by setting the **discharge
cutoff time to be lower than the time it takes the
cell to discharge to the cutoff voltage. For example...
if a cell takes 250 seconds to discharge to .90 volts
(the cutoff voltage) then it is safe to assume that
as long as the discharge cutoff time is set to be
at least 250 seconds, the average voltage calculation
will be correct. But what happens if the discharge
cutoff time is set to 200 seconds? Well, the answer
is simple... the average voltage will be calculated
only for the first 200 seconds of the discharge, resulting
in an average voltage much higher than it would be
if calculated for the full discharge. Pro-Match always
sets the discharge time to 5000 seconds, so that the
average voltage calculation will always be correct!
Beware of matchers that change this value or do not
print this number on their labels at all! The higher
the average voltage, the faster top speed your motor
will have. Average voltage is most important to people
who race in stock oval classes.
Internal Resistance
- The resistance of the cell's internal structure.
A cell's internal resistance is a key factor in the
amount of 'punch' it can provide. The lower the internal
resistance, the quicker the energy can be released
from a cell, giving you more "bottom end"
power. This number is most important in off-road,
touring car, and small tight oval tracks where fastest
acceleration is needed.
Discharge Cutoff Time
- Number of seconds before terminating the average
voltage calculation. Make sure this number is on the
cell and set to 5000 (default setting) Team
Orion also has a great battery question page that
can be found here. Team
Orion Battery FAQ
What temperature in Farenheit should a battery
reach when being charged by a peak charger?
GP3300 - 125 Degrees
Panasonic 3000 - 108 to 115 Degrees
Sanyo 3000HV and 3300 - 120 Degrees |
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