a large extent, the performance and longevity of rechargeable batteries
depends on the quality of the chargers. Battery chargers are commonly
given low priority, especially on consumer products. Choosing a quality
charger makes sense. This is especially true when considering the high
cost of battery replacements and the frustration that poorly performing
batteries create. In most cases, the extra money invested is returned
because the batteries last longer and perform more efficiently.
There are two distinct varieties of chargers: the
personal chargers and the industrial
chargers. The personal charger is sold in attractive packaging
and is offered with such products as mobile phones, laptops and video
cameras. These chargers are economically priced and perform well when
used for the application intended. The personal charger offers moderate
In comparison, the industrial charger is designed for employee
use and accommodates fleet batteries. These chargers are built for repetitive
use. Available for single or multi-bay configurations, the industrial
chargers are offered from the original equipment manufacturer (OEM). In
many instances, the chargers can also be obtained from third party manufacturers.
While the OEM chargers meet basic requirements, third party manufacturers
often include special features, such as negative pulse charging, discharge
function for battery conditioning, and state-of-charge (SoC) and state-of-health
(SoH) indications. Many third party manufacturers are prepared to build
low quantities of custom chargers. Other benefits third party suppliers
can offer include creative pricing and superior performance.
Not all third party charger manufacturers meet the quality
standards that the industry demands, The buyer should be aware of possible
quality and performance compromises when purchasing these chargers at
discount prices. Some units may not be rugged enough to withstand repetitive
use; others may develop maintenance problems such as burned or broken
Uncontrolled over-charge is another problem of some chargers,
especially those used to charge nickel-based batteries. High temperature
during charge and standby kills batteries. Over-charging occurs when the
charger keeps the battery at a temperature that is warm to touch (body
temperature) while in ready condition.
Some temperature rise cannot be avoided when charging nickel-based
batteries. A temperature peak is reached when the battery approaches full
charge. The temperature must moderate when the ready light appears and
the battery has switched to trickle charge. The battery should eventually
cool to room temperature.
If the temperature does not drop and remains above room temperature,
the charger is performing incorrectly. In such a case, the battery should
be removed as soon as possible after the ready light appears. Any prolonged
trickle charging will damage the battery. This caution applies especially
to the NiMH because it cannot absorb overcharge well. In fact, a NiMH
with high trickle charge could be cold to the touch and still be in a
damaging overcharge condition. Such a battery would have a short service
A lithium-based battery should never get warm in a charger.
If this happens, the battery is faulty or the charger is not functioning
properly. Discontinue using this battery and/or charger.
It is best to store batteries on a shelf and apply a topping-charge
before use rather than leaving the pack in the charger for days. Even
at a seemingly correct trickle charge, nickel-based batteries produce
a crystalline formation (also referred to as ‘memory’) when left in the
charger. Because of relatively high self-discharge, a topping charge is
needed before use. Most Li-ion chargers permit a battery to remain engaged
without inflicting damage.
Charger: Also known as ‘overnight charger’ or ‘normal charger’,
the slow-charger applies a fixed charge rate of...
Charger: The so-called
quick-charger, or rapid charger, is one of the most popular. It is positioned
between the slow-charger and the fast-charger, both in...
Charger: The fast-charger
offers several advantages over the other chargers; the obvious one is
shorter charge times. Because of the larger power ...
the Nickel Cadmium Battery:
Battery manufacturers recommend that new batteries be slow-charged for
24 hours before use. A slow charge helps to...
the Nickel-Metal Hydride Battery: Chargers for NiMH batteries
are very similar to those of the NiCd system but the electronics is generally
more complex. To begin with, the NiMH produces...
the Lithium Ion Battery:
The Li-ion charger is a voltage-limiting
device similar to the lead acid battery charger. The difference lies in
a higher voltage...
at High and Low Temperatures:
batteries can be used under a reasonably wide temperature range. This,
however, does not automatically mean that...
charger manufacturers claim amazingly short charge times of 30 minutes
The charge and discharge current of a battery is measured in C-rate.
The typical end-of-discharge
voltage for nickel-based batteries is 1V/cell.