I did some preliminary work with the BQ24650 solar panel battery charger controller eval board, it seemed to work ok with a 12V Lead Acid battery. I’ve got the circuit on a custom PCB now and I have some questions because it indicates charging but there is no current going to the battery:
- I’m only getting 2mA of current from the bench supply set to 9.0V (going into the solar cell input), the STATUS signals says we are charging after the start up delay.
- The buck regulator is switching. It detects the battery.
- I’ve tried both states of TERM_EN with no difference in charging. I don’t understand that feature.
- I discharged the battery to 4.8V last night (VFB set to 5.6V at the voltage divider).
- I can force it to stop indicating charging by setting:
MPPSET < 1.2V
Thermocouple input out of range
The voltage across the current sense resistor (0.04 ohms for 1.0A current limit) is virtually 0.0V.
I did a point-to-point verification between our schematic and the eval board, no issues found.
We are using a NiMH battery pack (4S, 4.8V nominal, charge to 5.6V), but at 1Amp charge there should not be a problem.