#12766 HIGH Opportu: XO-1.75 not charging batteries

Zarro Boogs per Child bugtracker at laptop.org
Fri Apr 25 21:35:23 EDT 2014

#12766: XO-1.75 not charging batteries
           Reporter:  Quozl     |       Owner:  Quozl      
               Type:  task      |      Status:  new        
           Priority:  high      |   Milestone:  Opportunity
          Component:  hardware  |     Version:  1.75-C1    
         Resolution:            |    Keywords:             
        Next_action:  diagnose  |    Verified:  0          
Deployment_affected:  ni        |   Blockedby:             
           Blocking:            |  
Changes (by wad):

 * cc: wad at laptop.org, gary at laptop.org (added)
  * version:  Software Build 13.2.0-13 => 1.75-C1
  * component:  embedded controller => hardware


 Can you also provide a measurement of the DC voltage at PQ61.1 (giving me
 the Vgs voltage on PQ61) ?    Since the systems operate fine without a
 battery (?), the components in question are PQ61, PR185 (usually open, not
 shorted), and PU16.  I've also seen weird problems caused by marginal
 battery cabling in the base unit (but not this particular problem).

 BTW, it is useful to have both the AC and DC measurements for the (very
 AC) GATE signals, in lieu of scope traces.

 The voltage across PQ61 should be: < 0.2V for charging and somewhere
 between 0 and 2V otherwise (depending on the battery voltage).  I suspect
 the last measurement (PQ61 volt., working unit) was due to accidentally
 shorting the
 battery to ground while making the measurement.

 The voltage between BGATE and VBAT_S is more informative.   If 0V, there
 is no charging and DC power is applied.   If it is > 1.5V, the battery is
 being charged or DC power is missing.  If between 0 and 1.5V the MOSFET is
 being used in linear mode to trickle charge the battery.   In theory, this
 should only be seen in units where the battery voltage is below 5.3V or
 so.  If this is happening and +VIN is above 5.5V, then it suggests that
 PU16 needs replacing (requires hot air tools and is difficult due to a
 thermal plate underneath the chip well bonded to the MB ground plane).

 It might be interesting to lower the MinSystemVoltage setting in the
 ISL9519 (PU16) to see if they can be made to work with special EC code.
 Just make sure the real +VIN stays above 5.4V or so.

Ticket URL: <http://dev.laptop.org/ticket/12766#comment:5>
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