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.