Use a voltage converter
If you don’t want to use an MMPT charge controller you can also use a voltage converter. This will take the 12V from the solar panel and convert it into 24V.
However, this is a less efficient way to do it because you’re losing some of the power in the conversion, but it will work as long as the voltage converter is rated for at least 24V.
This method is going to be less efficient than using an MPPT charge controller, and it will also take longer to charge the battery.
It is also important to note that most solar panels produce 30% more than what they are rated at. A 12V solar panel is typically a 36-cell module that produces around 18V. Similarly, a 24V solar panel is typically a 72-cell module that produces around 36V – 44V.
There are also a lot of 60-cell modules on the market that are rated at 24V, but they actually produce closer to 30V – 40V. So in reality, 12V solar panels aren’t truly 12V, and 24V solar panels aren’t actually 24V.
PV modules generate a constant current provided the constant daylight level is maintained. If you check the back of your solar panel, you will notice two values Isc (short circuit current) and Imax (maximum current). These two values are typically very close to each other.
This is the current that your solar panel will produce regardless of the voltage. Remember that by connecting a “12V panel” to a 12V battery, you are actually reducing the 22V of the panel to 12V.
That means the current (amps) produced by the solar panel will also be reduced causing the overall charging process to take longer.
This is where an MPPT can help. An MPPT is essentially a self-adjusting DC-to-DC converter that automatically adjusts itself to run your PV module at the optimum power level and then down-convert the voltage so that you can charge your 12V battery at the full current.
An MPPT can help to increase the charging current and overall efficiency of the system. This is because it is able to extract more power from the solar panel, which will result in more amps being put into the battery.
You can use an MPPT charge controller to increase the efficiency of the charging process, wire the solar panel in parallel to increase the amperage, or use a voltage converter to convert the 12V to 24V.
Lithium-ion batteries are powerful, but they are also fragile. When you are moving or handling the battery, do so with care. The last thing you want to do is drop it on a hard surface, bump it against a sharp corner, or put large amounts of pressure on the battery casing.
As mentioned above, keeping your Renogy battery within the recommended temperature range is critical. Make sure it stays out of extreme sunlight or heated areas that could reach temperatures higher than 149°F. Batteries are often stored in garages or outdoor shops but depending on the weather in your area and the ventilation offered by your space, that could lead to a disaster for your battery.