Solar Charge Controller not Charging Battery Troubleshooting

Solar Charge Controller not Charging Battery Troubleshooting

Expert step-by-step DIY directions for troubleshooting and fixing a Solar Charge Controller not Charging battery problem properly.

Solar Charge Controller not Charging Battery?

If the solar battery is hooked to the solar system but doesn’t charge properly, the failure is likely to be caused by a battery problem, wrong system wiring, or a problem with the solar charge controller settings. (Note: The Panels, charge controller, and battery must be configured correctly.) To diagnose the problem, do the following:
  1. Use a multimeter to measure the entire system, from the solar battery and solar charge controller to the solar panel, first disconnect the solar panel and measure the voltage, as long as there is sunlight, there will be solar output. If the voltage cannot be measured, it may be a problem with the solar panel or rectifier diode. It is also necessary to measure the voltage of the battery. If the actual voltage of the battery is less than 20% of the nominal voltage. This is when an extra charger is needed to charge the battery.
  2. Measure the terminal output voltage of the solar charge controller, examine whether the output voltage is within the proper range. If the output does not reach the defined value, it probably the solar controller that has problems, replace the charge regulator to try.
  3. the next is to test the solar batteries, Measure the Battery Voltage, make sure the battery voltage is not too high nor too low. too high or too low both affect the charging.

Solar Charge Controller not Charging Battery Factors Checklist

Broadly, there are 4 factors you’d need to consider.
  • solar charge controller factors
  • solar panel factors
  • solar battery factors
  • environment factors like weather
Let’s understand each of the scenarios one by one.

Solar Panel Charge Controller Factors

Solar Panel Charge Controller Enters Charging Protection Mode to stop the charging

1. Direct charge protection point voltage: Direct charge is also called rapid charge. It’s a fast charge process. Generally, the battery is charged with high current and relatively high voltage when the battery voltage is low. However, there is a control point, also called a protection point. The point is the value in the above table. When the battery terminal voltage is higher than these protection values during charging, the direct charge should be stopped. The direct charge protection point voltage is also the “overcharge protection point” voltage. When charging, the battery terminal voltage cannot be higher than this protection point, otherwise, it will cause overcharge and damage to the battery. ‍ 2. Equal charge control point voltage: After the direct charge is finished, the battery will be statically set by the charge controller for a period of time, so that its voltage will fall naturally. When it falls to the “recovery voltage” value, it will enter the equal charge state. Why design an equal charge? That because after the fast charge, there may be some batteries that are “backward” (the terminal voltage is relatively low) to the battery bank. To pull these individual molecules back and make all the battery terminal voltages have equal consistency, it is necessary to match the high voltage with a moderate current to recharge the battery for a short while, so it called equalization charging also called balanced charging. The charging time should not be too long, usually from a few minutes to ten minutes. The longtime setting is not good. A small system with a two-cell battery doesn’t make much sense to use the equal charge. Therefore, the street light controller generally does not have an equal charge, only two stages. 3. Floating charge control point voltage: Generally, after the equal charge is completed, its terminal voltage naturally falls. When it falls to the “maintenance voltage” point, it enters the floating charge state, when the battery voltage is low, it will be charged a little. and the battery will continue to rise. High, this design is very good for the battery, because the internal temperature of the battery has a great influence on the charge and discharge. In fact, the PWM method is mainly designed to stabilize the battery terminal voltage, and the battery charging current is reduced by adjusting the pulse width. This is a very scientific charging management system. Specifically, at the end of charging, when the remaining capacity (SOC) of the battery is >80%, it is necessary to reduce the charging current to prevent excessive outgassing (oxygen, hydrogen, and acid gas) due to overcharging. 4. Over-discharge protection voltage: It is easy to understand. Battery discharge cannot be lower than the rated value. the battery manufacturers also have their own protection parameters (enterprise or line standard), for safety reasons, the 12V battery over-discharge protection point voltage is artificially added plus 0.3v as the zero-drift correction of the temperature compensation or control circuit, so that the over-discharge protection point voltage of the 12V battery is: 11.10v, then The over-discharge protection point voltage of the 24V system is 22.20V. At present, many manufacturers of charge and discharge controllers use the 22.2v (24v system) standard. Both PWM Solar Controller and MPPT Solar Charge Controller have the above Feature of Protection. The MPPT controller is recommended when you have a long-term demand for solar power. we have made a comprehensive MPPT vs. PWM guide here.

Solar Panels Factors

1. Solar Panels do not output Power, Confirm that the solar panel connection is correct, and make sure the positive and negative poles did not reverse connect. 2. Check the Solar Panel to make sure the panels did not block by shadows nor cover by stains to ensure the solar collection. 3. Check whether the specifications of the solar panel are correct. whether the open circuit voltage meets the requirements of the controller. 4. Check the power of the solar panel exceed the rated value of the solar controller or not. if The power is too high, which may cause the solar controller to burn out. 5. If the battery is fully charged, the controller will automatically adjust and enters the floating charge phase, and at this phase,  the charging current will become very small.

Common faults with solar panels

1. Hot spots

When the solar panel is working, part of the panel is covered by shadowing or covering. The temperature of the covered part is much higher than the uncovered part, and obvious hot spots will appear after a long time. Damage of hot spot: when the hot spot effect reaches a certain level, it melts the solder joint of the module, destroys the grid line, and damages the whole solar module. According to statistics, the hot spot effect greatly reduces the generation rate of solar power plants and reduces the plants’ service life by 10%.

2. The snail

The panels appear in a black or white linear pattern that looks like a snail’s trail. This kind of photovoltaic circle is called “snail tracks.” The reason for the “snail pattern”: the panels crack, water seeps in, and sunlight causes chemical reactions.

3. Cracking problem

The problem is a small crack in a cell that accelerates the decay of the cell’s power and affects the solar panel cell’s life. At the same time, the cell chip cracking problem continues to expand under mechanical load, which may lead to open circuit failure, and can also lead to a hot spot effect. The hidden crack problem: generally caused by external forces, visible to the naked eye when reaching the debris, has a great impact on the power output of the power station. The hidden crack is difficult to be found by the naked eye and has a certain influence on the power output of the component.

Battery Factors

The battery is Fully Charged but Run out Soon.

1. Check Whether the battery capacity design is reasonable, if the capacity is too small, then the running and supply time will be short. 2. The battery is aging, the service life of the battery is generally 2-3 years, the capacity of the battery is greatly attenuated, after this period, the battery needs to be replaced regularly. 3. Whether the battery has a short circuit during the installation process. Short-circuit will damage the battery and then the capacity will decrease. 4. The load power exceeds the design power.

Battery Low Voltage Protection

When the battery is run out of power and idle for a long time, it’s hard to charge the battery by the solar system directly, Now you need to check the voltage of each battery, find the lowest voltage battery out and fill it with a large current charger. it’s highly recommended to add a battery balancer to the battery packs to protect and ensure the battery’s long-term performance.

Faulty Battery

If a battery in the battery pack is damaged, the entire battery will not be successfully charged. Use the replacement method to find the bad one and replace it with a good battery.

Weather Factors

Weather factors, if there is no sunshine for a long time, will result in less solar collection, and the output voltage may too small to charge the battery.

Solar Charge Controller not Charging Battery Treatment:

1. There is an open circuit or certain device damage, the treatment method: replace or repair the device 2. The sun is not strong enough, the treatment method: move to a place where it is easier to collect sunlight. 3. Voltage mismatch, processing method: increase the booster, add several photovoltaic panels in series


Solar Charge Controller not Charging Battery is a very common problem that many people will encounter and it is easy to solve. Just follow the above instructions step by step to troubleshoot and then replace it to restore the vitality of the solar system. or connect a zhcsolar expert for help, go to the contact us Where to Buy the Best Quality MPPT Solar Charge Controller? ZHCSolar Offers the Best Quality and Reliable MPPT Solar Charge Controller, Get Free Shipping Now. Related Articles Best MPPT Solar Charge controller Guide of 2023 Solar Charge Controller Ultimate Guide in 2023 Solar Battery Equalization ultimate guide (2023)


Will a solar panel charge a dead battery?

No, the Solar Charge controller will automatically detect the battery voltage and if the battery dead, the charging process won’t work, we recommend using an Individual Battery Charge to Fix and Restore the Dead Battery before reconnecting it to the solar system.

How to Read Solar Charge Controller Error Code?

Solar Charge Controller Error Code indicates whether a specific Problem the Charge Controller Detected, Following the User Manual to resolve the problem.

Load output on solar charge controller not work?

1. Confirm whether the working voltage of the load is consistent with the controller output voltage. 2. Whether the load is short-circuited or overloaded. 3. Is the controller load output manually turned off? 4. Whether the battery voltage is too low or too high, which may cause controller load protection

how to reset a solar charge controller

reset means to restore the controller to the factory default settings, including system voltage, output voltage, and other parameters, follow the instructions to restore the factory settings. check this guide for how to reset charge controller.

how to troubleshoot a charge controller

If the solar charge controller has a problem charging the battery, the reason is likely to be caused by a battery problem, wrong system wiring, or a problem with the solar charge controller settings.

solar charge controller not turning on

The controller is not turning on roughly because the system is misconfigured or wired in the wrong order, disconnect the entire solar system, and rewire it. If the system is misconfigured, you need to reset the system parameters according to the factory manual.

How can I check that my solar charge controller is working?

The easiest way to test if the solar controller is working is to use a multimeter to test the output voltage. and look to the controller’s LCD and Led indicator, if the output voltage is absent or very low, It means that the controller is not working properly.

Solar Charge Controller not Showing amps

The solar controller is not displaying amps most likely due to a system configuration error, reset the solar panel voltage regulator, or reconnection of the entire system.

Solar Charge Controller no-load output

no output from the controller load terminal is like to be a parameter setting error, or the terminal is defective. If the solar controller is running normally, use a multimeter to test the load port output voltage, reset the system, and re-program the controller.
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