How
should I care for my NiMH batteries?
NiMH
cells are somewhat new to the R/C market. For that reason, we are continually
learning more and more about how to charge and care for these batteries.
Our current battery care recommendations are to follow. Please check back
periodically as we will make changes to this section should we discover
better battery care methods.
Sub-C
NiMH cells that are used on a regular basis are fairly easy to maintain.
You only need to discharge them after you run them and put them away.
They should be discharged to .9 volts per cell in the pack. So a 6 cell
pack will be discharged to 5.4 volts. This can be achieved by monitoring
the voltage of the pack as it discharges with a Voltmeter. The pack will
not rest at 5.4 volts. When the pack cools it is okay to charge it again.
We have found more than 2 charge cycles a day is detrimental to pack performance.
The packs can be stored like that if they will be used again in about
a week. You only want to charge packs to be stored for a couple minutes
(2-5) if they will be stored for 2 or more weeks. It is very important
that you discharge them before you charge them back up or they will false
peak. Packs that sit for extended periods of time may false peak when
they are first used again. This is normal and will happen with all NiMH
cells. You can re-peak the pack and use it. The pack will be back to normal
after 2-3 charge cycles.
If
you are using a charger that uses Voltage Threshold to determine the peak
of the pack, you should set the Voltage Threshold to 4 mV/cell. The Millennium
Pro has NiMH2 charge mode which does not use any type of voltage threshold
to determine the peak. It is the best method for peak charging NiMH cells.
How
should I care for my NiCD batteries?
NiCD
cells have been around for years and are being phased out slowly due to
their harmful effects to the environment. They are relatively easy to
care for. After use, they should be discharged to .9 volts per cell (That's
5.4 volts for a 6-cell battery) and stored. They should only be used on
time a day for optimum performance and battery pack life.
Why
does my Millennium Pro false peak?
It
is very unlikely that the charger would cause the false peaking issue.
Typically the battery pack is the culprit. If the pack is brand new, it
will false peak until it has a few good cycles on it. If the pack is very
old, or has not been used for a long time, you will see the same problems.
See the Battery Care section for more information. If the pack has any
loose connections between the cells it may false peak. If the connection
between the charger and the pack is not clean, you will see false peaks.
What
is PEAK DETECTION?
When batteries reach a fully
charged condition, the pack's voltage begins to drop. A charger that uses
peak-detection senses this drop in voltage and changes from a high rate of
charge to a trickle charge (or off in the pulse mode). Digital peak detection
is more accurate than analog peak detection.
What
is DIGITAL PEAK DETECTION?
Digital peak detection measures
the battery voltage and stores that information as a digital binary number.
This number does not change due to temperature or drift over time. An analog
peak circuit stores that same voltage information in a capacitor, which can
lose information as time passes (measured in seconds), and is greatly affected
by temperature. Digital Peak Detection is the only way to achieve an accurate
peak value.
What
is the difference between LINEAR and PULSE CHARGING/REVERSE PULSE?
In Linear Mode charging,
constant current is maintained by varying the applied voltage to the battery
to maintain the user-set current value. In the PULSE MODE, voltage applied
to the battery is 100% of the source voltage. The user-set current value is
obtained by the on/off time of the voltage applied (PWM). For example, if
100% voltage causes 10 amps to flow into the battery, to obtain a 1 amp charge
rate, 10% duty cycle is used. This means for any given pulse, the on time
is 10% and the off time is 90%.
What
is TRICKLE CHARGING?
Trickle charging is a reduced
rate of charge usually described as the battery capacity divided by 10. This
small amount of trickle current allows cells to equalize after their fast
charge cycle has been completed. Trickle charging tends to slightly suppress
the voltage of the battery pack, and is generally not used for racing.
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