Brief Information About Batteries; Nickel Cadmium Batteries (Nc) - ROBBE 8194 Instrucciones De Uso

13.

BRIEF INFORMATION ABOUT BATTERIES

13.1

NICKEL CADMIUM BATTERIES (NC)

In the field of model construction, nickel cadmium batteries (in
model building jargon "NC batteries") have a secure position
as drive batteries and for supplying power to remote control
units. These power sources are efficient, easy to maintain and
reliable. Nevertheless, some principles should be observed
when dealing with the batteries. They will thank you for it with
longer service life and the highest degree of available capacity.
Charge rate
The term "charge rate" (C) has established itself for the size of
the charge and discharge currents. It creates the connectivity
between charge current and battery capacity.
If, for example, a battery with a capacity of 600 mAh is to be
charged with a rate of '1 C', then there must be a current of
600 mA flowing.
Forming
A new battery, or one that has not been used for a long period
of time, must be formed before use. An exhaustively dischar-
ged battery, which can lead to some of the cells having their
polarity reversed, must also be formed again first. The battery
is formed over 20-24 hours with a charge rate of 0.1C. The
Profi Homecharger has the regeneration mode (D/C) available
for this purpose.
Charging
A charge rate of up to 0.1 - 0.2 C is called normal charging.
Since you always have to charge the battery more than you
can discharge, the charge time for normal charging with 0.1 C
is not 10 hours but 14 hours. That means that the overcharge
factor is 40 % for normal charging.
Longer charging of this type will only cause damage with over-
charging of more than approx. 100 hours; however, this should
be avoided as the electrical energy introduced is no longer
saved, but chemical processes are released which reduce the
service life of the battery.
There is an accelerated charging if a charge current flows at a
level of 0.3 - 0.5 C.
Quick charging is when you charge the battery with rates of
more than 1C.
With larger charge rates than 0.1 C, the charge current must
be interrupted as soon as the battery is fully charged. The digi-
tal delta peak process, for example, is suitable as disconnect
criterion. This evaluates the undervoltage which occurs when
the battery is completely charged up.
Depending on the level of the charge rate, a battery builds up
different crystal structures. For this reason, with high current
discharging of drive batteries there must be a quick charge.
The higher the charge current selected, the lower the voltage
collapse during discharging.
We recommend the following charge rates for NC batteries:
High energy batteries, 1-2 C, please also observe the details
from the battery manufacturer.
High current batteries, 2 -3 C, extreme up to 5 C. Observe any
maximum charge current details from the battery manufactu-
rer. Check whether the plug-in connection and/or the charge
cables are suitable for the selected charge current.
Profi-Home-Charger
24
Self-discharging
Self-discharging of NC cells is approx. 0.5...1% per day
(20°C). That means that after approx. 100...200 days, a pre-
viously fully charged battery is completely discharged without
being strained at all. Batteries must therefore be recharged
before use.
Storage
If a NiCd battery is not used for a foreseeable period of time it
is better to discharge it beforehand and then store it in a cool
and dry place. Then, after one forming, the battery will gain
nearly its full capacity. If the battery is not discharged before-
hand then the first charging will only result in about 90 - 95 %
of the voltage and capacity and it will only achieve full capacity
after 2-3 charge cycles.
Service life
Depending on the application and use of the charge proce-
dure, NC batteries have a service live of approx. 500...1000
cycles. After this, the battery is used up and must be disposed
of in an appropriate manner.
Temperature
The NiCd battery heats up very markedly during a high current
discharge. The cells must therefore be cooled down before
charging. A warm or even a hot cell absorbs less charge and
can accordingly release less energy.
Discharge end voltage, exhaustive discharge
Measured under load, the permissible discharge end voltage is
approx. 0.85 volt per cell (this is automatically set by the Profi
Homecharger).
Exhaustive discharge occurs during further discharging. This
can lead to pole reversal of one or several cells. Pole reversed
cells change their polarity. There is minus potential at the plus
pole and plus potential at the minus pole (if there is low loading
check with the voltmeter).
Cell defects can be prevented by immediate 14 hour normal
charging.
NC batteries are not as sensitive to exhaustive discharge as
NIMH batteries.
Storage over a long period of time in an exhaustive discharge
condition can however also lead to cell defects with NC batte-
ries.
When handling NC cells, some safety precautions must be
observed to prevent bodily injury or material damage. You
assume responsibility when using these batteries.
- Never allow NC cells to come into contact with open flames
as there is a risk of explosion.
- Never open NC cells with force as there is a risk of acid
burn.
- Never short-circuit NC cells as there is a risk of burning and
explosion.
- Never allow secreted electrolyte to come into contact with
skin or eyes. If this should happen by accident, rinse gene-
rously with water and find a doctor. Never put batteries in
your mouth as there is a risk of poisoning.
- Never solder with the solder iron on the cell casing.
- The minus side of the cell is particularly sensitive.
- A charged NC battery is not a toy. Batteries should be kept
out of the reach of children.
- Observe the information from the corresponding battery
manufacturer when charging and discharging.
Order No.
8194