TrakPower VR-1 Dual Racing Charger - Manual (Page 11)

11
NOTES FOR CYCLING NICD AND NIMH BATTERIES:
•
Periodic cycling of NiCd batteries (once every month or two) can be benefi cial in keeping
them in good operating condition. Excessive cycling (more than once monthly) will
unnecessarily shorten the lifespan of the battery.
• During cycle mode, the discharge cutoff voltage for NiCd and NiMH is FIXED (not adjustable)
at 0.9V per cell.
• Cell manufacturers note three main benefi ts of cycling NiCd and NiMH batteries:
1. Battery maintenance: NiCd batteries benefi t the most from regular cycling to help keep
them in good operating condition, and is recommended once-monthly. NiMH batteries
do not require as much cycling.
2. Determining battery condition: NiCd and NiMH batteries are rated by how much charge
energy or “capacity” they can store compared to their rated capacity. A battery that
can supply only a small fraction of its rated capacity is likely reaching the end of its
useful life and may need to be replaced.
3. Breaking in batteries: new NiCd and NiMH batteries may need to be broken-in before
they will perform to their specifi cations. Older batteries which have been unused for an
extended length of time may require to be broken-in again to regain their usefulness.
Repeated cycling is the best way to revive such batteries.
6. STEP CHARGE
CAUTION! The Step Charge method is recommended for use by experienced users only!! If set
improperly, the Step Charge method can cause severe, permanent damage to the battery! If
you are unsure about how to use this function, do not use it.
The Step Charge method is designed for very high charge effi ciency for NiMH batteries. This
feature can be used on NiCd batteries also, but only if the peak sensitivity value is set properly
(see page 7). NEVER USE THE STEP CHARGE MODE WITH LI-ION, LIFE, OR LIPO BATTERIES AS
SEVERE, PERMANENT DAMAGE TO THE BATTERY AND ITS SURROUNDINGS WILL RESULT!!
Parameters which are set in the Step Charge screen do NOT affect those which are set in the Main
Memory screen. A temperature sensor IS REQUIRED. When using the Step Charge mode, VR-1 will
not allow Step Charge to start unless a temperature sensor is connected.
The Step Charge method divides the overall time needed to charge a battery into four separate
periods or “steps”. The maximum charge capacity and charge current is set separately for each
of the four steps. The purpose of the Step Charge mode is to deliver as much energy to the battery
as possible for racing “punch” without damaging the battery, but also to allow for the most
accurate peak detection as possible for maximum run-time.
In the beginning, for charge step 1, it’s important that the battery’s voltage becomes stable, so
the charge current setting should be rather conservative. Then, when the battery voltage is stable,
much higher current can be delivered in Step 2. The higher currents in step 2 will cause the
battery to generate heat after a period of time, so it is best to reduce current in step 3. Finally, for
step 4, it’s best to reduce current again so the battery’s voltage is more stable which will allow
the peak detection circuit to work more accurately to pack as much run-time capacity in the
battery as possible. It is important to note that in Step Charge mode the peak detection circuit
functions ONLY in step 4 (not steps 1-3).
The maximum amount of charge capacity delivered to the battery during each step effectively
determines how long the charge current will be delivered to the battery during the step. Be careful
not to set the capacity value too high – especially in steps 2 and 3 where the current settings are
higher. The higher the capacity setting, the longer that current will be applied to the battery during
the step, and the more likely the temperature sensor will trip due to heating and stop the charge
process prematurely. It may take some practice and careful attention to dial-in the Step Charge
mode for your battery. See the chart that follows for a breakdown of the settings for each step.