Lead-Acid Battery is the most popular. Though they are a very large size. But they have an advantage are: cheap, easy to buy. If you need long life. You should use an Automatic battery charger circuit below.
Charging best importance
Usually, these battery types can use for 3-4 years with correctly charging. I feel sick every time the battery break down before the time should. I do not want you to be like me. Do not do these!
- Overheat charging
The important, battery does not like hot! At all time, do not use or store them in too heat area.OR If while use may short circuit or high current use them will too hot. While charging does not quick charge with high current and high voltage.
- DC voltage only!
We must charge them with DC voltage only.
- Overvoltage charging
Normally, the battery manufacturer usually prints the appropriate voltage.
We should use a constant voltage charge.
—12V battery maximum voltage of 14.8V, Standby use is 13.8V
—6V battery maximum voltage of 7.5V, Standby use is 6.8V
- High current fast charge
But hot—So you should use initial current less 30%. For example, 12V/7AH battery you should the initial current less 2A. If we use 1A, the battery will be full for about 7 hours.
- No long time
Also, If you charge it for too long times. The battery is also too hot. Thus, When the battery is full, stop charging it.
These two circuits help make your life easier.
Table of Contents
Simple Automatic battery charger circuit
This is the first automatic battery charger circuit. We use the concept of the circuit: not using ICs and complicated devices. Use existing products to use more benefits.
We can use this circuit for all battery. Just have to understand Battery charging requirements only.
- It is designed for 12V batteries. But if you understand the working principle already. I believe you can definitely adapt for a 6V battery or others.
- You should use an input voltage of 15-volts or 1.5 times of a battery voltage.
- Most importance—Should use charger current 10 % of battery current. For example 2.5Ah battery. Use the charging current 0.25A. It will take 10-12 hour for full.
How it works
First of all, I think “When…Charge? And When stop?”
Normally we should charge the battery if the voltage is lower than 12.4V. Then the battery voltage rises and the voltage maximum 14.4V. It is full. We need to cut off the charging current.
Secondly, we need to use a comparator circuit.
I often use IC-op-amp such as LM339, LM311, LM324, LM301. But sometimes we cannot buy them.
And This our working is simple style only.
In the begin, we learn a basic principle of electronic parts.
Meet Zener Diode
I like use Diode, Zener diode, which they are both valves for electrical currents. The Current will flow one way. But the Zener diode is connected backward. It then blocks current until the voltage exceeds a certain level.
I try to test them with the Zener diode 12-volts the current will flow through it when a voltage higher than 12V.
So, I use Zener diode for detects voltage over than 13V to control stop charger system.
Relay and SCR cut-off battery
Then, I use a relay to control the current to a battery. Because of cheap and used easily.
Next, I use a SCR for uses as quick control switch.
Simple automatic cut off battery charger
Look at the circuit. Suppose, the voltage battery is 12.4V. The relay does not work. The charging current flows continuously through the battery.
Until the voltage of the battery rises up to 13.8V. Starts to has the current flowing through Zener diode to Bias SCR1.
The SCR1 is working. Then replay also runs, pull in the NO and C connecting.
So no current flow to the battery.
How to setting and use
You can watch the video below I test it. This projects will always cut off the battery. When the voltage drops across it are 13.6V down.
Then LED2 (yellow) glow brightly. While the relay will pull out from the contact NC-C. Which no current to battery and voltage lower down.
Then you can charge again with pressing SW2 to reset, recharge them again.
Though This projects will easy technology but very useful for all.
Importance it cheaper! I love it.
Automatic OFF 12V Battery Charger by power SCR
This stop current give battery, when Voltage of battery tall arrive at the level that load with full speed already ahead for protect something charger too much poor distilled dry water. This circuit can is usable very wide can use with battery many model. By choose diode and SCR at can durable the trend loads topmost follow to want. Fining decorates while initial lead battery at charger until with full speed ahead already come to build reach at a pole for charger. Fine R1 – 500Ohm until Amp Meter begin be down be O as a result fully be usable already.
Note : above circuit is just basic ideal only we lets to see really uses below.
Auto dry battery charger using SCR
This projects is automatic dry battery charger that can use for many size such as 6V, 9V and 12V Depending on the changes, some devices only.
How this circuit works
As circuit below. To begin with an AC220V will flow to a transformer to transform to 15 volts, then flow to bridge diode to rectifier AC to DC is 15V. The LED1 is power indicator of the circuit.
Beginning SCR1 is working, because the 15V flow to R3, to limit the current to decrease, and flow through to diode D5 to To prevent the reverse voltage, Before bias to lead G of SCR1.
While SCR1 conduct, to make the 15V flow from lead K will feed to the positive battery terminal. Ideally SCR1 will conduct current and stop current alternately very fast with frequency of 100 Hz.
Since the 15V voltage from the bridge diode is full wave rectifier so output frequency of 50+50 Hz. The feature of current will be continuous positive half sine wave.
Which will differ with the voltage from capacitor filter that is smooth as a straight line. So will see that SCR1 do not conduct current all time. When have positive voltage to bias at lead G. Since waveform of voltage Not smooth enough in a straight line.
Theoretical of SCR, it will stop conducting current when disconnect the power supply output. Which in this circuit is do not have positive side of the power supply range. And when have positive voltage waveform new SCR1, it starts to currents again, this was reversed with a frequency 100 Hz.
Battery level monitoring
This circuit will get voltage from the battery positive through R2 to reduce current, and have C1 to filter current to smoothly. Then will flow through VR1 to divide voltage to feed to a zener diode ZD1 before send to bias lead G of SCR2.
A adjust level of VR1 will must make in full battery, adjust VR1 until voltage at negative of ZD1 have level more than 6.8V or about 7.3V.
Which will cause ZD1 to saturation voltage collapse flow through to ZD1 to feed lead G of SCR2, cause SCR2 conducting current by R4 is helper to SCR2 extraordinary stable work. When SCR2 work will cause negative voltage flow to lead K to A result to LED2 glow. And the same time SCR1 will stop conducting current.
Since lead G of SCR1 get negative voltage from SCR2 there. In the case of battery is lower voltage, cause voltage at negative of ZD1 have lower than 6.8V, makes lead G of SCR2 not get positive voltage but can get only negative voltage through R4 result SCR2 don’t conduct current.
The parts list
R1, R5: 2K
R3: 560 ohm
VR1: 10K Potentiometer
C1: 100uF 25V Electrolytic capacitor
ZD1: 6.8V 1W
LED1, LED2: 5M LED as you want
PCB, and others, etc.
How to make and setting
After preparation equipment is ready, then we soldered it successfully on PCB as Figure, next checked again. For example, The device has a positive – negative. Are they correct polarity?
To Safety, customization first step, to find full battery voltage fit, be connected to the circuit to correct polarity. Then apply AC220V , next adjust VR1 clockwise until LED2 go out. Then to rotate VR1 clockwise slowly until LED2 light up, then stop immediately, do not too much spin is strictly prohibited. The principles, LED2 will light when battery voltage until full. So the battery will be adapted for the first circuit has to be really full voltage.
Please watch video below to increase understand this projects.
This saving dry the battery circuit, can charge voltage 3 size are 6V, 9V, 12V. We can change each value parts as neat charged battery.
For this circuit we use with 12V battery Look at the chassis battery is stated as 12V 20AH, mean, Battery voltage 12V currents supply 20 amps per hour. When you know voltage at the battery is charged, Now I have to choose the transformer to be used. currents transformers used can be selected from 3-5 A.
The table below shows the change in each device. To fit the battery charger.
Zener Diode voltage
R3 and R5
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