Building a solar panel charger that is functional with several battery types is discussed in this article.
By modifying a tiny component of the circuits zener diode which can power batteries with voltages of 12V, 24V, or even 48V.
As a result it can be used for a wide range of purposes
What is a High Current Solar Battery Charger Circuit for 12V, 24V, 48V Batteries:
A circuit for a high current solar battery charger is made to effectively use solar panels to charge batteries.
In order to safely charge larger batteries such as 12V, 24V or 48V batteries which are often used in solar power systems due to which circuit must be able to handle higher currents.
To control the charging process and safeguard the batteries against deep draining or overcharging this design generally includes a solar charge controller.
How the Circuit Works:
Parts List:
| Category | Component | Quantity |
|---|---|---|
| Resistors | 100Ω 1W CFR | 1 |
| Semiconductors | Schottky Diode (STPST15H100SB) | 1 |
| Zener Diode 15V 1W | 1 | |
| Transistor TIP35 | 1 | |
| Heatsink for Schottky Diode | 1 | |
| Heatsink for Transistor TIP35 | 1 | |
| Solar Panel 18V 10Amp | 1 |
An emitter follower setup is used with transistor TIP35.
The transistors base is connected to a zener diode in this configuration while the emitter is connected straight to the solar panels positive terminal.
A voltage reference is provided by the zener diode.
Since a 15V zener diode is used in this high current solar battery charger circuit the transistors base voltage is set at about 15V.
This causes the transistors output voltage to be set to about 14V for a 12V battery.
The diode stops reverse current flow and ensures that current only moves from the solar panel to the battery.
The solar panel has an 18V/10A rating.
To charge the battery the transistor controls this voltage to a suitable level.
Its ability to charge batteries at different voltages i.e 12V, 24V and 48V is what gives this circuit its versatility.
This can be achieved by adjusting the value of the zener diode.
Thus a 30V zener diode should be used with a 24V battery and a 60V zener diode when using a 48V battery.
The circuit serves as a voltage regulator keeping the output voltage for battery charging somewhat stable.
It is important to keep in mind that this is a basic design and that other features such as temperature adjustment, overcharge prevention and suitable voltage/current limitations are necessary for the best possible battery charging and its safety.
It is advised to carefully inspect, test and think about safety precautions to protect the batteries and the circuit before putting such a circuit into use.
Also one must be caution because lead acid batteries can be dangerous particularly when charged incorrectly.
How to Match a Battery to a Solar Panel:
Before charging a battery gets to know about its voltage (V) and ampere hour (Ah) rating.
Confirm that the solar panels output voltage and the necessary battery voltage match.
In general the solar panels voltage should be used close to the batteries voltage but not much higher.
Lithium-ion and lead acid batteries for example have distinct charging behaviors.
One should be sure the solar panel voltage and battery chemistry ahold match to avoid harm.
Two examples of factors that might impact the charging time are the depth of discharge and the desired charge rate.
Choose a charging time that fits ones needs.
It is best to choose a solar panel whose current rating is equal to or higher than estimated required current.
The battery will be efficiently charged by doing this.
Use a solar charge controller to control the charging process.
Charge controllers not only protect against overcharging but also provide other functions for better battery maintenance.
Check the location and weather conditions where the solar panel will be placed.
A batteries capacity to charge can be impacted by a number of factors such as temperature, shade and sunshine availability.
The performance of solar panels is affected by temperature.
Confirm that the panel one choose operates well within its desired temperature range.
Be sure that the solar panels and the batteries connections work together.
Check that the charge controller and other necessary parts that are capable of managing the entire voltage system.
Example:
Let say one have a 12V 100Ah lead acid battery and want to charge it in 5 hours.
Required Current = 100Ah / 5 hours = 20A
One would choose a solar panel with a current rating of 20A or higher.
Formulas and Calculations:
Below mentioned formulas shows how much current (in Amps) needs to supply to charge a battery completely in a specific amount of time.
Required Current (A) = Battery Capacity (Ah) / Charging Time (hours)
Required Current (A):
The electrical current required to charge the battery is represented by Amps (A) used to measure it.
Battery Capacity (Ah):
This is the entire quantity of electrical energy that a battery is capable of holding.
Amp hours are used to measure (Ah).
Consider it to be the same size as an electrical container.
A greater capacity to hold more charge is indicated by a higher Ah rating.
Charging Time (hours):
This is how long it takes for the battery to charge completely.
Hours (h) are used to measure it.
How to use the formula:
Find the Battery Capacity:
Check the battery for the Ah rating.
The battery itself usually has this printed on it.
An average smartphone battery for example have a 3000mAh (milliAmp hour) capacity.
Divide this figure by 1000 to convert it to amp hours (Ah) as 1mAh equals 0.001Ah.
Because of this 3000mAh / 1000 = 3Ah.
Decide on Charging Time:
Consider how long one would like the battery to charge.
The demands and ones chargers capacity will depend on this.
Calculate Required Current:
Enter the desired charging time (hours) and battery capacity (Ah) into the formula.
For example if 3Ah battery needs to be charged in 2 hours:
Required Current (A) = 3Ah / 2 hours = 1.5A
This shows that in order to fully charge the battery in two hours one need a charger that can deliver at least 1.5 amps of electricity.
Note:
In addition to be to simple this calculation ignores charging issues.
The real charging times can be a little bit longer.
When it comes to charging your particular battery always follow the manufacturers instructions.
Certain batteries could have restrictions or requirements when it comes to charging.
How to Build:
To construct a high current solar battery charger circuit for 12V, 24V or 48V batteries follow the instructions mentioned below:
- Find the TIP35 transistors emitter, base and collector pins.
- Using a 15A diode cathode of the diode facing the solar panel connect the collector to the solar panels positive terminal.
- Directly connect the emitter to the batteries positive terminal.
- Anode of the zener diode should be connected to TIP35 transistor base.
- The zener diodes cathode should be connected to the circuits negative or ground side.
- Mount the solar panels negative terminal to the batteries negative terminal.
- The TIP35 transistor could generate some heat.
- Be certain that it has a location that allows adequate heat dissipation such on top of a heat sink.
- Once the solar panel is connected to the circuit monitor the voltage between the battery terminals.
- Ensure that the voltage is within the battery types safe charging range.
- To protect circuits against overcurrent use safety devices like circuit breakers or fuses.
- Keep an eye on the process of charging to be sure the battery does overcharge.
- Additional parts such resistors or capacitors are often required for stability or filtering, depending on the requirements.
Notes and Considerations:
- To avoid overcharging be sure the voltages from the solar panel and Zener diode are suitable for the type of battery used.
- Before using the circuit to charge expensive batteries test it in a controlled atmosphere.
- For advanced battery charging management and protection features think about including a charge controller.
Safety:
- Keep in mind that creating this circuit for a high current solar battery charger requires a certain level of skill therefore if you are not familiar with electronics one should get help from an experienced person or speak with an expert before trying to construct this circuit.
- To prevent mishaps or damage follow the safety rules and regulations as well.
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