BQ24250: BOOSTXL-BATPAKMKII: BQ24250 fast charge on BOOSTXL-BATPAKMKII

Have uploaded a short video of the random current swinging after 1.48A

drive.google.com/.../view

Hi,

I am unable to download the video from google drive.  Do you have an oscilloscope to show VIN, VBAT, IIN, IBAT?  If there are current meters in series with the input supply and/or battery, can you remove them and retry?

Regards,

Jeff

Hi Jeff

Thanks for the speedy reply. My apologies for the earlier google drive link that did not work. The following link should work now

drive.google.com/.../view

What I have done and observed since this afternoon.

a.) Swinging current - will come to this in a moment below.

b.) Tied EN1 to 3V3 HI from the 3v3 regulator, EN2 to 0

c.)  ILIM to GND => 2A input current limit so that battery can be charge at 1.92A (Riset = 130Ohm)

d.) VDPM to GND => Vin_dpm 4.68V

Observation

a.) The swinging current looks like it's in a trickle charge stage which stopped after around 45min - 1hr.

b.) Current drawn by PSU slowly increment from 0.72A to 0.765A after 4hours 23mins of charging, I was not able to observe any 2A drawn from my PSU to charge the LiPO battery at any stage. My current LIPO charger is a linear 5V/1A with power path and it takes around 7hours to fully charge my 4000mAH, I was hoping with the BQ24250 with max 2A charging that I am able to reduce charging time (in STAND ALONE MODE) to ~3.5hours but it looks at the moment not promising.

c.)  Anomaly of BQ24250 or other chips onboard - from the beginning of this morning, I intermittently noticed that when I plugged in my 4000mAH battery to this booster pack, switched on PSU, the current was "shorted" to 6mA, though I do know it is around 20mA with no battery connected. I need to physically unplugged the battery, switch off the PSU and wait a few seconds before plugging the LIPO battery back, switch on the PSU that current is being drawn above 20mA, to the region of 700mA instead. Not sure if this has to do with BQ24250 switching from I2C and Stand alone mode or? Ideally I would want a STANDALONE mode without intervention from uController due to PCB space.

Just one more question, can a ~2 hour fast charge be achieved for my 4000mAH with the BQ24250 2A charge configuration as the datasheet seems to only spec and test up to 1000mA charging.

If ~2hrs fast charge can be achieved, may you kindly advise the optimal hardware configuration for BQ24250 booster pack, BOOSTXL-BATPAKMKII, so I can evaluate it for our design. Thanks

Hi,

First, I did not design the BOOST pack and only support the charger itself.  Host software can overwrite the default settings (for charge current, input current limit, and VINDPM) for the I2C registers per the charger pins.  The charger should be able to provide close to 2A charge current with 5V, 2A input current.  Based on your pin settings and resistors, I would check the voltage at the charge input pin and make sure that is not at the VINDPM threshold due to line resistance drop.  Also, I would check the TS pin and make sure it is at ~2.5V. 

For further support, I will need oscope plots of VIN, IIN, VSYS, ISYS and then VIN, IIN, VBAT, IBAT.

I suggest you order an EVM for the BQ24250 only.  Or, you might check out one of later devices like BQ25616 standalone 3A charger.

Regards,

Jeff

Hi 

Will get the BQ24250EVM to test out, I suspect it might be the Gas Guage that might be causing some issues as it acts as a bridging between VBat battery and Vin.

Just to confirm, that I am planning to design a charger with no host interface, ie uController. May you confirm that the hardwire connections, for STANDALONE mode, I made are correct and that no I2C interface is needed?

Jonathan