BQ25895: Unexpected IINDPM and charge current too low

Here's the local circuit:

One more thing.  In the datasheet, the definition of Bit 1 of REG0B is missing, so I don't know if there's a general error in the doc for this register.

Wyatt,  Thanks for the quick answer.  Sorry for my slow followup, as the email notification about your reply went into my spam folder.

So, following up.  I understand your 7.5W total power mention.  That load is roughly 860mA @ 4.3V, call it 3.7W.  This would leave about 3.8W for battery charging.  At roughly 4.3V this leaves about 804mA.  This seems reasonably consistent with the facts.  This suggests I need to increase IINLIM.  Oh, ignoring Watts and just counting amps, 1.5A - 860mA => 640mA for charging.  Even more consistent.

I tried IINLIM=2.5A (REG00 == 0x30, HiZ disabled, ILIM pin disabled).  No increase.  I tried IINLIM=3.25A.  Still no increase.

HOWEVER, maybe my drained battery was already charging too quickly for me.  I'll go try discharging the battery fully again.  In the mean time, I have a followup question for you.  Is it **ALSO** perhaps my problem that I'm limiting the charge voltage to 4.352V (REG06), and my battery is very quickly charging enough such that internal resistance in the battery is limiting the current to a similar ~600mA while I'm limiting the charge voltage to 4.352V?  That is, since I'm not allowing the charger to push higher than 4.352V, then at around that voltage, ~600mA is all that will go into this battery at that charge voltage.  Oh... is REG06 "Charge Voltage Limit" (A) the highest voltage the chip will apply to the battery, or (B) the highest voltage the chip will let the battery charge to?  I was thinking (B) originally, but maybe it's (A).  There can be a difference.  I'm not sure how to differentiate between these two, however, to prevent overcharging.  Termination current?  Now this gets complicated!

If **THAT** is the case, then I wonder about increasing the charge voltage limit.  This is a 3500mAh battery from a small tablet, rated at 3.8V, but I know the original tablet would charge it up to about 4.32V.  I'm hesitant to push in a higher voltage than the max charged voltage.  (I haven't analyzed how hard the tablet itself would push.)  Perhaps you can suggest some things, perhaps point me to some educational materials or something about what's safe to do in this regard.  (While I have decades of EE experience, I have little with charging this kind of battery.)

Later, nevertheless, after I've discharged my battery again, I"ll see if the higher IINLIM indeed provides for more charging current.  I do know that in that very discharged state, the charger chip is NOT pushing in the full 4.325V, only 3.8V or 3.9V in the beginning.

Here's an update, Wyatt.  Having fully discharged the battery overnight, and having set IINLIM=3.25A, I now see much higher battery charge current, as desired.  My 12V bench supply began at 1.80A into the overall system, while in the past it never exceeded 1.36A.  That extra 0.44A at 12V must have been very high current into the battery.  By the time I could get into my processor debugger, the 12V bench supply had dropped to about 1.60A.  That's because the battery had already charged up a bit.  At this point, the charger chip regs reported 1100mA.  Much higher than my earlier ~650mA. 

Therefore, indeed, the increase to IINLIM=3.25A was indeed my solution for this very low battery scenario.  I'm now getting in excess of 1A charge current into the battery.  In fact, extrapolating backward to when my bench supply read 1.80A, it's likely I was getting far over 1.5A into the battery for several seconds.

Meanwhile, I noticed the both my scope on the battery and the chip's ADC for battery voltage were reading roughly 4.3V.  That means the charger chip is limiting itself to ~4.3V, as I hypothesized earlier with REG06 "Charge Voltage Limit'.  Fortunately, because the battery began so fully discharged, that ~4.3V pushing into the battery was able to push over 1A.  That through the battery's internal resistance and to the battery's very low internal charge level.

So now I'm confident that the charger chip will simply START at pushing ~4.3V into the battery, and the charge current will start well above 1A and then gradually decrease as the battery's internal charge rises, that current amount being limited not by anything in the charger chip or my external system, but instead by the actual internal resistance of the battery.  This means that ALL IS GOOD now for the charger chip and the rest of my system.

That just leaves the final question I have.  Is it safe to increase REG06 and push, for example, 5V into the battery, as long as I stop before the internal battery charge gets above 4.3V (or the battery overheats, and I am using the temp sensor, or the battery simply _______ or something due to overcharging).  I will go measure a virgin tablet to see how high a voltage it ever pushes into the battery.  I don't think I should exceed what the original manufacturer was doing, even though I want to charge as fast as I can.