tips

Battery Chargers: How to Choose and Use

The use of personal and portable electronics in the outdoors continues to grow. Devices include digital cameras, music players, cell phones GPS units and emergency locator beacons. Additionally, expeditions are often outfitted with laptop computers, iPads and satellite phones.

Most of these devices rely on an internal rechargeable battery for power. Functionality is lost when the battery is discharged. To meet the need for recharging these devices when a wall outlet is not convenient, a growing choice of portable battery chargers is available. These provide auxiliary power to recharge or operate your device. Most have the versatility to charge a range of electronics, but some are designed for specific items only, like the iPhone.


Quick Tips on Battery Chargers


1. Know the power input requirement (in volts) of your electronic devices. Find a charger that delivers the same or greater output.
2. Get a power pack if you do weekend trips and want backup emergency power or a single recharge.
3. Add a solar charging panel to a compatible power pack for longer trips requiring multiple recharges.
4. Use a stand-alone solar charger if you can get regular exposure to direct sunlight. To do so, it must be practical to have the panel laid out and charging a device during your trip.
5. Be aware that

• Some personal electronics cannot be used while they are being charged up, and
• You cannot charge a device from a power pack while the power pack is being charged by a solar panel.

6. Start out with your device’s batteries fully charged. A solar panel or power pack may not provide a full recharge.
7. iPhone users should consider using a charger designed specifically for this purpose.

advantage & disadvantage using solar charger

advantage:

Solar battery chargers enable you to make electrical energy even if you are in the ocean. With the chargers, you can always be assured of electrical energy even when there is blackout. The solar panels can neither be damaged by ultraviolet rays nor water. They are hardy and cannot be damaged by the impact of rain drops. 

solar battery charger also saving energy, convenient and economical.

disadvantage:

charging a battery from a solar panel is never easy because 

1. the voltage from a solar panel can vary hugely, depending upon the incident rays

2. the current also varied due to the same above reasons.

fyp DEMOSTRATION

DATE : 25 APRIL 2013
VENUE: GEMILANG HALL, UNIKL BMI
TIME: 9.00 am - 12.30 pm
ASSESSOR: madam zaba & sir zubair (lecturer from medical electronic)

prototype of alternative charger using solar energy

poster

result

 full circuit

figure top: phone charging

figure bottom: voltage at rechargeable battery (back up battery)

  

figure top: voltage for rechargeable battery charge by solar panel

figure bottom: charging STOP when the rechargeable battery FULL

block diagram

the circuit of charging controller uses a 7.2V solar panel and a variable voltage regulator which LM317.

once the solar panel get the energy from sunlight, the LED will turn ON. 

the charging current passed through diode to the LM317 by using adjust pin, output voltage and current can be regulated.

variable resistor placed between the adjust pin and ground to provide an output voltage of 5v of battery. 

resistor and diode to prevent discharge of current from the battery.

the solar will charge the rechargeable battery back up and also charge the battery phone directly. if NO solar  energy, the back up battery can charge the phone.

as at the pic controller, there have power supply circuit which using voltage regulator of 7805 to convert the DC voltage from 9V to 5VDC. this is because the 5VDC using to operated the PIC and relay driver. PIC will show the value of voltage and the relay will be as a switch to cut off the current when the charger fully charge. then, it will avoid overcharging.

problem 5

protection of circuit.

it need diode and resistor. especially diode which separate diodes may be needed to avoid reverse current in case of partial or total shading at night.

circuit burn because no diode for reverse bias  and the current can flow through it.

problem 4

because i used a really small amount of current. (48mA). when it flow through voltage regulator, the current also regulate into a small value. then, it is not enough current to flow into usb socket or to phone.
it is because:

usb socket need 500mA at least to connect the charger & some phone need at least 120mAh before they will  start charge phone

then, i need to use a larger of current for solar panel.

problem 3

when charging using solar panel: increasing the the power of battery phone

when charging without solar panel: decreasing the power of battery phone

this is because the circuit stable the power between the back up battery with battery at the phone.

solar panel

electrical connection are made in series to achieved a desired output voltage. in parallel to provide a desired a current capability.
because i want make it more high current, so this solar panel must be in parallel connection.

7.2 V and 6V is parallel

p/s: this connection are wrong ! it is because, when it need to make a parallel connection, there must be same voltage. then, one of them will broken because it will be reverse bias.

problem part 2

 because current too low to charge the cell phone, this circuit need more current because current from the solar panel too low.

how to solve?

need to change the solar panel? using  a bigger solar panel with high power?

need to buy another solar panel to make it more current? series it?

new battery

rechargeable battery. 6V. 1500mAh. Ni-MH.

all specification is what i really want for my project. but this battery too difficult to find and too expensive compared to other because it is rare.

problem

first, i'm using battery non-rechargeable to test the circuit. then, i change into rechargeable battery. when going to buy the battery, the 6v was to difficult until one shop have it. but it not Ni-MH but Ni -cd.

because of i'm want to charge to become high voltage after using it. using the solar is to slow. then, i want make it faster by using the charger of 6v. but it is not suitable and make it broken and burn it.

after charging:

p/s: i need to find another rechargeable battery. it is must be Ni-MH battery 6V because the Ni-cd too low their current.

circuit

full circuit

charging controller:
if solar panel  have the voltage, the LED will light ON. then, the current will flow to recharge the rechargeable battery or charge the cell phone.

voltage sensor:
connected from charging controller to pic circuit

pic controller & relay:
as the controller and LCD will display  the voltage in the back up battery .

make a PCB circuit board

1. The first part, we have to print the circuit diagram at the iron on PCB paper.
2. Cut the paper following the paper with the size needed of our PCB board.
3. Ironing the printed iron on PCB to the PCB board until the ink stick to the PCB board.
4. After the circuits have stick at the board, drill the entire hole that needed for all the components
5. After that, we have pour an acid to make the circuit can be used
6. Clean the board with the thinner.
7. Solder all the components at the PCB board to complete the process

design pcb using software

after design circuit at protues, then it need to design the pcb. there show one of the circuit.

pic circuit with relay 

MPLAB part 2

still in progress.

MPLAB

for this project, i'm using pic16F877A to control and to show the LCD. so, this wee, i'm start to make a coding. after searching at internet, there have a few reference based on the project that i'm will produce.

protues part 1

still in making to construct one of part in the project. half of the circuit

protues

start to construct the circuit using software by using PROTUES before test it at the board. so, the problem like component burn, broken or so on will minimize.

new sem for FYP2

in this sem, i continue from FYP1 to FYP2. this sem, i need to construct circuit, and the end of week 14, there has demonstration for my project.

BATTERY

DIFFERENCE between non-rechargeable and rechargeable battery:

• Non rechargeable batteries are called primary batteries, while rechargeable batteries are called secondary batteries

• A chemical reaction goes inside non rechargeable batteries’ that release electricity needed to run appliances

• The chemical reaction can be reversed to send or rush electricity inside rechargeable batteries to charge them

• Non rechargeable batteries are cheaper than rechargeable batteries that however prove to be more cost effective because of their ability to be recharged hundreds of times.

Types of popular rechargeables:

NiCad (Nickel Cadmium)- Cheapest and if not properly maintained will get a memory drastically reducing their battery life (drain quicker). Not for use in high drain devices like cameras - unless you like to pack lots of batteries.

NiMH (Nickel Metal Hydride) - Long life, middle cost, no memory - need special chargers - smart or passive. Good for high drain devices

Lion (Lithium Ion) - More specialized batteries. Last a really long time. Most expensive in most cases. Good for high drain devices. Usually require smart chargers.

p/s: i prefer NiMH because the current are higher compare to other rechargeable battery.