I use a solar controller (14V) to charge the battery (12V). I want to use it in parallel to increase the capacity.
It is said that the circulating current flows between the batteries and the batteries are completely discharged soon after.
Of course, that means if the car is equipped with an auxiliary battery and the voltage goes up and down...
The isolator price was too expensive.
So, how do I do it with a diode?
Which of the 1,2,3 is the best?
(You can see the arrow as a diode in the picture above.)
If there is a problem for each case, please let me know why.
From my point of view, it seems that the second and third times will be fine without any problems.
The purpose of using the isolator when charging and discharging by connecting batteries in parallel is to prevent charging and discharging between batteries and to ensure proper charging.
It is best to use an isolator to charge and discharge batteries in parallel.
However, if the isolator is expensive and the purpose is to simply connect the load and use it, the next best thing is to use the 3rd circuit.
In this case, industrial diodes should be used, and industrial Schottky diodes with sufficient voltage and allowable current should be purchased and installed.
At this time, attach the diode to the (+) pole.
The solar controller is 14V above...
There is no problem when the solar module operates normally due to good sunlight conditions.
However, in these days when the sunlight is bad, there are times when not all batteries can be charged with a solar module.
At this time, the batteries are charged together, and both are undercharged, so the efficiency may be worse.
Looking at the appropriate power generation amount of the solar module,
If you cannot charge all of the batteries a day, you can use only one battery and use it as above when sunlight is good, such as in summer.
Therefore, when the sunlight is not good these days, you have to bear the inconvenience of manually attaching and dismantling the battery.
If you don't have that worry because there are many solar modules, the next best thing to do is connect it to No. 3 and use it.