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Linear battery charger with long distance between bat. and charger output

avraka
Intellectual 855 points
Other Parts Discussed in Thread: BQ24072, BQ24250C, BQ24060

Dear Tier.

Could you kindly let me know what is the proper battery charging solution for wireless headset with logn distance between battery and the charger output?

When I charge the battery(capacity 800mAh) using BQ24072, It was not fully charged due to CC/CV on the cable loss.

Charger IC is on the left side of headset, and the battery is on the other side. The distance between bat. and charger IC is about more than 30cm.

How can I solve this issue?

It wolde be very appreciated to share any information for the transition from CC to CV.

  • 0
    TI__Guru**** 166916 points

    I assume that the battery doesn't completely charge because the safety timer runs out?

    The IC begins transition from CC to CV when the voltage at its BAT pin measures 4.2V.  Since V(BAT)=Icharge*(Rcable+Rbattery+Rconnector) + V(cell, the larger Rcable + Rbattery+Rconnector, the earlier the IC will start to taper the current.  Using a less resistive cable/traces/connectors is the best solution. 

  • 0 in reply to Jeff F
    Intellectual 855 points

    Really thanks Jeff.

    Can I use bq24250C to compensate the cable loss by programming Vattery Charge Voltage?

  • 0 in reply to avraka
    TI__Guru**** 166916 points

    I do not recommend that unless you can accurately predict the amount of voltage drop due to resistive losses and slowly scale back the regulation voltage so that you do not overcharge the battery.

    One of our older non-power path devices (bq24060) has a separate BAT pin that can be used as a remote sense.