BQ25820EVM: Battery charger keeps reverting to hardware charge current value

Tool/software:

Hi

I'm evaluating the BQ25820 and BQ40Z50 devices for a 3S1P 10650 Li-ion battery pack - the cells are 3.7V nominal / 3500mAh

I have tried setting the charge current to 1750mA using the ICHG_REG register (the default hardware setting is 10A) but the device keeps jumping back to the value of the hardware limit.

Even when JP4 is open and JP3 shorted to ground, the value keeps jumping back to something far too high for my evaluation cells. I am trying to limit the charging to 1/2C during the evaluation.

I have added a resistor across JP3 (30K) to give a hardware limit of 1.6A. Even when the ICHG_REG is changed to 500mA and it starts charging at this value, after a very short while it jumps back to the hardware limit.

Since my design includes the BQ40Z50 which seems to need to be driven by an external host, the host may as well control all aspects of the charger as well - but this is slightly worrying as it is not behaving as per the datasheet / EVM manual.

Any suggestions to make the software charge current limit stick?

Thanks in advance.

Max