Competition Electronics Turbo35-GFX User Manual page 19

When charging properly functioning NimH packs, during the first part of the charge
process the cells will self heat slightly. NiCd cells do not exhibit this self-heating
behavior before peaking. For both types of cells, temperature will rapidly rise as the pack
nears full charge. Normally, for good cell longevity, it is desirable to minimize cell
heating as much as possible. However, in R/C racing, there are definite advantages to
heating your cells! It turns out that the performance of warm cells is noticeably superior
to cold cells. It will then be better to peak your cells right before a race, so that they are
warm when you use them. Also, some racers thermally insulate the pack while charging,
to cause the pack to build more heat during the charge process, while maintaining a lower
peak detect voltage.
Another factor that will heat the pack is a higher charge rate. A higher peak detect
voltage will also result in a hotter pack. But don't forget that excess heat does damage the
cells and will shorten their life. Normal treatment of NimH cells would dictate as small a
peak detect voltage as possible, to avoid as much heat as possible during charging, but
R/C racing is different!
Cell "Venting"
Both NimH and NiCd cells have vents at the positive electrode end that will release
pressure (and electrolyte) when the cells are charged. This venting is normally to be
avoided. It will occur at higher charge rates. Repeated venting will certainly degrade
cells.
TurboFlex: What is it and what does it do?
Your T35-GFX includes a feature called "TurboFlex", also known as "burping".
TurboFlex is only intended for use with NiCd cells. The rationale behind TurboFlex is
this: Charging NiCd cells can cause crystalline deposits to build up inside them, resulting
in performance degradation. Periodic discharge pulses delivered during a charge cycle
can reduce these deposits, thus improving performance. Using the TurboFlex feature is
not beneficial when actually charging for use in a car, but rather should be regarded as a
conditioning procedure. Do not use TurboFlex when charging your cells for racing.
The T35-GFX is set up for variable adjustment of the TurboFlex feature. The settings go
from 1 to 9, with 1 resulting in the lowest ratio of discharge to charge time, and 9 the
highest. In the case of the T35-GFX, the TurboFlex discharge rate is fixed at 5 amps.
TurboFlex will not take place, regardless of the setting, if the charge current is <= 3A.
This is built into the T35-GFX.
Discharging
The T35-GFX includes a discharging function that can discharge at rates of up to 35
amps. With this feature, you can test your cells and packs and measure their performance.
You can tell when the performance is falling off, and you can extend the performance of
your packs by re-matching cells and combining similar cells into packs.
Discharge Rate and It's Relationship to Performance
Over the years, CEI has repeatedly increased the discharge rate of our
charger/dischargers. This is because our customers demanded the higher rates. One
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