K8012 Charging Problem

Hi, I am using Velleman K8012 charger for my project. But there is some modifications that i have done as follows.

  1. I have remove the bridge rectifier because my project is dealing with pure DC (my input source will be a DC-DC converter)
  2. I have remove the 6V switch (which means i have removed R1, R4, T1, and R5).

I have built the solar charge controller on the PCB as according to the schematic diagram attached. It seems that it does not want to charge the battery. When the circuit is connected to the battery and input is coming from the DC power supply (we have set the DC input voltage from power supply of 14.2-15VDC, the End of Charge LED and Float Charge LED is on even though the battery is not full. We measured the output of the voltage and current but it seems no current is flowing and a voltage of 11.7V came out as the output.

But when the we short the positive and negative output wires only Charging LED light is on. We measured the current and voltage. Current is 0.3A(switch open) and 0.87A(switched closed) (as expected) but the output voltage is around 3V only.

According to schematic shows 3 output readings at pin 9 (0.7V), pin 8 (130mV) and pin 12 (50mV). We manage to obtain the output of pin 8 and pin 12. As for pin 9 we measured an unexpected output of 1.4~1.5V. I have no idea why we could not achieve 0.7V. I can’t find R29, R30 and R31 for 0.6w but only can find 1W versions and its big.

The main problem is that the battery can’t draw current from the circuit and for pin 9 we cant get the expected output.

Please kindly reply whats the solution to solve this matter.

Thank you.

Hard to tell what is going on.
Does it work when used as intended and without modifications?
That’s the way to start if you want to troubleshoot this circuit.