Wednesday, May 11, 2016

AA, AAA, and 9 Volt battery charger PCB circuit schematic

There are hundreds if not thousands of online schematic for battery charger that you can find in Google However finding efficient charger that can charge a battery at expected performance is another. You can easily find any charger schematic that can charge but how long it will charge or does it charge at all?

This is a very simple PCB schematic for 250 volt 6 amp battery charger made from simple component and of course step down transformer. It charger AA, AAA, and 9 volt battery. The efficiency is not bad can charge battery quite fast and effectively for nickel cadmium.

Without load (battery being charge) the voltage is around 12.30 volt after load is in the voltage will adjust to 1.37 volt

However of course the perfect battery charger should be able to output voltage at 5 volt with or without load.



Components

3 x 1N4007 diodes
2 x 4148 Zener diodes
Step down transformer (240 vol) to 12 volt DC
2.2 uF 400 volt Capacitor (electrolytic)
2A103 Ceramic capacitor
47 uF 50 volt capacitor (electrolytic)
325 Ohms resistor
2.2K Ohms resistor
1 3001 transistor
1 M resistor
600 ohms resistor
332 ceramic capacitor
100 uF 16 volt (electrolytic) capacitor
1K Ohms resistor
18 Ohms resistor

Efficient battery chargers general output rating usually as follows

voltage output ~ 5 volt DC
amperage output ~ 1.5 amp to 2 amp

There are too many circuit schemas out there but the efficiency is far below the standard stated above. The output amperage is the most significant and some cable can also affect the output amperage. You can find many Chinese super cheap chargers but the output current (amp) is way below 1.50 amp for example like 200 mili-amp or 500 mili-amp. Even at 1 amp can hardly charge anything.

When the output amp is below the requirement a battery either charge too slow or sometimes don't charge at all. So always look at the output current rating before buying a charger. It can be extremely cheap but absolutely useless. We can test a phone charger by playing the phone and if the battery charge percentage doesn't go up or going down when playing the phone it means the charger is not efficient. A good phone charger should be able to charge regardless if the phone is in idle mode or active.

Example of inefficient charger no rating stated but after tested using multimeter the output amp is around 200 amp is way below what is required to charge a battery. The voltage can be increase to boost the amp of output but excessive voltage more than 12 volt will smoke every component especially the IC as i've tested it myself.





5 volt @ 500mA USB phone charger direct connect to AC100~240v 50/60Hz simply not enough for a smart phone charging. Instead of going up the charge will go down because smartphone is actively using battery even if it is in idle mode.



This is one of the best power bank charger 5 volt ~ 2 amp current output. Charging while playing smartphone will still be fine as the maximum current is flowing to the battery. 2 amp usually the maximum for 5 volt charger more than that could make the phone getting hot easier and probably cause explosion to the battery



Example of Efficient charger - Samsung battery charger adapter output 5 volt DC and 1.5 amp current

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