This almost trivial circuit may be used to charge a pair of AA or AAA sized rechargeable battery cells from sunlight. The circuit has been used to keep a Palm Pilot and walkman radio running perpetually. This is an unregulated charger, proper charging is achieved by placing the unit in the sun for a known amount of time, this time varies according to the battery type.
Figure 1 is a generalized block diagram of a multichemistry battery charger. A COP8ACC5 µC handles its key charging features. The µC is available in a 20-pin (15 I/O pins) SOIC or a 28-pin (23 I/O pins) SOIC/DIP. It contains 4 kbits of internal ROM.
The circuit in Figure 1 can solve this problem by providing a constant 300-mV drop between VIN and VOUT at currents as high as 3A. The accuracy of the 300-mV drop is nearly as good as the accuracy of the input voltage, which in this case is approximately 1%. This circuit requires an input voltage that is fixed, regulated, and preferably current-limited.
When a discharged gel cell is connected, the charger goes into a fast charge mode at a fixed rate of 400 ma. After the chip detects the voltage leveling off or when 4 1/2 hours has elapsed. (which ever happens first.) the fast charge will stop. After the fast charge has ended, the IC goes into a trickle charge rate of about 50 ma. This trickle charge continues until 13.8 volts is reached which will stop all charging current since the cell is...
A simple circuit measures the open-circuit voltage, such as the expanded-scale voltmeter circuit in Figure 2, which follows the curve in Figure 1.
Sealed lead-acid batteries are available in several sizes, from a single D size (2.5 Ahr) to multicell rectangular battery packs.
This charger will quickly and easily charge most any lead acid battery. The charger delivers full current until the current drawn by the battery falls to 150 mA. At this time, a lower voltage is applied to finish off and keep from over charging. When the battery is fully charged, the circuit switches off and lights a LED, telling you that the cycle has finished.
This circuit was specifically designed to recharge alkaline cells. The unusual connection of the transistor in each charging unit will cause it to oscillate, on and off, thus transferring the charge accumulated in the capacitor to the cell. The orange LED will blink for around 5 times a second for a 1.37V cell. For a totally discharged cell the blinking is faster but it will decrease until it will come to a stop when the cell is charged. You...
Here`s how to make a good charger for a sealed lead-acid battery (this will NOT work with NiCad batteries) that`s faster (because it allows more current into the battery initially) and safer (because it uses lower voltage when the charging is finished). The battery can be left plugged into this charger indefinitely, and it won`t bother it in the slightest. In fact this is the "float" or "standby" charging method recommended by battery...
This circuit is for a temperature controlled constant current battery charger. It works with NICD, NIMH, and other rechargeable cells. The circuit works on the principle that most rechargeable batteries show an increase in temperature when the cells becomes fully charged. Overcharging is one of the main causes of short cell life, hot cells pop their internal seals and vent out electrolyte. As cells dry out, they lose capacity.
This simple charger uses a single transistor as a constant current source. The voltage across
the pair of 1N4148 diodes biases the base of the BD140 medium power transistor. The base-
emitter voltage of the transistor and the forward voltage drop across the diodes are relatively stable. The charging current is approximately 15mA or 45mA with the switch closed.
This application note presents practical design considerations
for battery chargers employing Green Mode FPS
(Fairchild Power Switch). It includes designing the
transformer and output filter, selecting the components and
implementing constant current / constant voltage control.
Figure 1 shows a typical dual battery charger. This circuit
can charge batteries with up to 4A and switch continuously
down to zero load currents. This circuit takes advantage
of ceramic capacitors space saving features without producing any audible noise. The high 300kHz switching frequency
allows the use of small low cost 10µH inductors.
Nowadays maintenance-free lead-acid
batteries are common in vehicles,
inverters, and UPS systems. If the
battery is left in a poor state of charge, its
useful life is shortened. It also reduces the
capacity and rechargeability of the battery.
For older types of batteries, a hygrometer
can be used to check the specific gravity
of the acid, which, in turn, indicates the
charge condition of the battery.
Charging of the cellphone battery is
a big problem while travelling as
power supply source is not generally
accessible. If you keep your cellphone
switched on continuously, its battery will
go flat within five to six hours, making
the cellphone useless. A fully charged battery
becomes necessary especially when
your distance from the nearest relay station
increases. Heres a simple charger that
replenishes the cellphone battery within...
Mobile phone chargers available in
the market are quite expensive.
The circuit presented here comes
as a low-cost alternative to charge mobile
telephones/battery packs with a rating of
7.2 volts, such as Nokia 6110/6150.
Rechargeable lithium-ion batteries are rapidly becoming
the battery of choice for many battery-powered products.
These products include notebook computers, PDAs, video
camcorders, digital cameras, cellular phones, portable
test equipment and others. Compared to other rechargeable
power sources, Li-Ion batteries have higher energy
density for both weight and volume and provide longer run
time between charges.
Li-Ion batteries are normally charged with a current
limited constant voltage for a fixed length of time. At the
end of this time period, the voltage must be removed to
prevent internal chemistry changes in the battery. At a
minimum, a timer is needed to terminate the charging
process after the maximum amount of time required to
fully charge the battery.
Linear battery chargers are typically smaller, simpler and
less expensive than their switcher-based counter parts,
but they have one major disadvantage: excessive power
dissipation when the input voltage is high and the battery
voltage is low (discharged battery).
The LT®1510 current mode PWM battery charger is the
simplest, most efficient solution for fast charging modern
rechargeable batteries including lithium-ion (Li-Ion), nickelmetal-
hydride (NiMH) and nickel-cadmium (NiCd) that
require constant current and/or constant voltage charging.
The internal switch is capable of delivering 1.5A DC current
(2A peak current).
The new LTC1155 Dual Power MOSFET Driver delivers
12V of gate drive to two N-channel power MOSFETs
when powered from a 5V supply with no external
components required. This ability, coupled with its
micropower current demands and protection features,
makes it an excellent choice for high side switching
applications which previously required more expensive
The charger is built around a single LTC®1541,
which contains a voltage reference, op amp and comparator.
The high accuracy voltage reference (±0.4%) regulates
the battery float voltage to ±1.2%, as required by most
Lithium-Ion battery manufacturers.
The block diagram in Figure 1 shows the basic functions
performed by a battery charger IC using this patented
topology*. The LT1511 is a high efficiency 200kHz switching
regulator IC in a step-down configuration suitable for
charging lithium-ion batteries. It contains multiple feedback
loops for constant charge voltage, constant charge
current and input current limit.
Typically such applications
require low power from the battery. With this in mind,
every feature of the LTC4100 Smart Battery charger exists
to reduce board real estate and profile requirements. The
LTC4100 is a Level 2 (slave) Smart Battery charger that is
compliant with both Smart Battery Charger V1.1 and
SMBus V1.1 standards.
The LTC®4010 and LTC4011 are NiCd/NiMH battery
chargers that simplify Nickel-based battery charger
design and include power control and charge termination
for fast charging up to 16 series-connected cells using a
synchronous buck topology. The LTC4011 provides a full
feature set in a 20-lead TSSOP while the LTC4010 comes in
a 16-lead TSSOP.
circuit possesses two vital features:
First, it reduces the requirement
of human attention by about 85 per cent.
Second, it is a highly accurate and
Input from the battery under test is
applied to LM3914 IC. This applied voltage
is ranked anywhere between 0 and
10, depending upon its magnitude.
The LTC1980 manages both battery charging and
generaton of the regulated system bus voltage via a unique
bidirectional pulse-width modulator design (Figure 3).
When the wall adapter is present, power passes directly to
the system load DC/DC converters and to a pulse widthmodulated
battery charger formed by M1, M2, T1 and the
The above pictured schematic diagram is just a standard constant current model with a added current limiter, consisting of Q1, R1, and R4. The moment too much current is flowing biases Q1 and drops the output voltage. The output voltage is: 1.2 x (P1+R2+R3)/R3 volt. Current limiting kicks in when the current is about 0.6/R1 amp.
For a 6-volt battery which requires fast-charging, the charge voltage is 3 x 2.45 = 7.35 V. (3 cells at 2.45v per...
Charging current is about 100+mA, which is the internally-limited maximum current of the LP2951. For those wondering, this is compatible with just about any single-cell li-ion battery since li-ion can generally accept a charging current of up to about 1c (i.e. charging current in mA equivalent to their capacity in mAh, so a 1100mAh li-ion cell can be charged at up to 1100mA and so on). A lower charging current just brings about a...
The circuit described here provides around 180mA current at 5.6V and protects the mobile phone from unexpected voltage fluctuations that develop on the mains line. So the charger can be left ?on? over night to replenish the battery charge. The circuit protects the mobile phone as well as the charger by immediately disconnecting the output when it senses a voltage surge or a short circuit in the battery pack or connector. It can be called a...
The above circuit is a precision voltage source, and contains a temperature sensor with a negative temperature co?ficient. Meaning, whenever the surrounding or battery temperature increases the voltage will automatically decrease. Temperature co?ficient for this circuit is -8mV per °Celcius. A normal transistor (Q1) is used as a temperature sensor. This Battery Charger is centered around the LM350 integrated, 3-amp, adjustable stabilizer IC....