3 months, 1 week ago.

Solar charge controller voltage threshold problem

Now I use an op amp to make an 11V to 12V range controller. When the battery is discharged to 11V, discharge is stopped until the battery voltage reaches 12V again. In the actual test, I used 1.5A current to discharge the battery. When the battery voltage dropped to 11V, the controller controlled to stop discharging, and then measured the battery voltage and found that it rebounded to 11.5V. I thought that it should be the current that pulls the voltage low, and the voltage during the discharge is not the voltage at the time of stabilization. Then how to solve the problem that the controller detects a virtual 11V triggers and stops the discharge.

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1 Answer

3 months, 1 week ago.

Just to check that I have this correct:

You have a battery that is being discharged.

When the battery voltage drops to 11 V you stop discharging.

When the battery voltage recovers to 12 V you start discharging again.

The problem you have is that when you stop discharging the battery rebounds to 11.5 V.

I'm sorry, I don't see any problem here. If you want to stop the discharge at a certain voltage then it is correct to be using the voltage under load rather than idle voltage. As long as the voltage doesn't rebound above your discharge start voltage (12 V) I can't see why there is an issue.

If you want to run the battery down to the point that the idle voltage is 11 V then set your off point to around 10.5 V.

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