Thursday, January 14, 2016

Recovering a Dead LiPo battery from "Low Voltage" with an IMAX B6AC battery charger

I was able to bring Big B's dead-dead LiPo Battery pack back to life.  Here's how.

We were out flying on New Years and Big B sent his shiny new Super Sky Surfer into the top of a particularly gnarly walnut tree. We got it down last weekend, but after a week the LiPo in it was stone dead.  His charger threw a Low Voltage alarm and wouldn't charge it.

Normally we charge these in LiPo Balance mode.  This won't work with a dead battery.  The trick is to slowly charge the battery at a low level to get it where the LiPo balance will work.  To do this I...
  • Place the battery in a fire resistant container, just in case.
  • Place the Battery charger in constant current (NiMH) Charging mode.
  • Set the current limit to 0.1 Amp.
  • Start charging:
    • Watch for any sign of battery failure.
    • Do not leave the charging battery unattended.
  • Charge the pack until it reaches a voltage that is acceptable to the balance charger.
    • I used 10 volts, i.e. 3.3 volts times the number of cells.
      • 1s = 3.3 volts
      • 2s = 6.6 volts
      • 3s = 9.9 volts
      • 4s = 13.2 volts
      • Ns = N * 3.3 volts, where N is the number of cells.
  • Stop charging.
  • Check to make sure the battery is not hot.  If it is, let it cool.
  • Switch the charger to Li-Po Balance Charge:
    • I don't want a fire on my desk, so I limited the Balance charge to 0.1 Amp to prevent overheating.
  • Start Balance Charging.
    • Do not leave the charging battery unattended
  • The charger should stop automatically.
My charger stops after 2 hours whether the battery is charged or not.  It was cool the whole time, so after it shut off I restarted the Balance Charge with a current limit of 0.2 amps.  After a half hour it was still cool to the touch, so I upped it to 0.5 Amps.  That ran for 2 hours and got it up to 11.6 volts.  I upped the charging current to 1 amp, and 30 minutes later Beep-Beep!  It's done!

This worked for me; I hope it works for you.

Hat tip to Youtube user NOTEB00KPC for this idea!

Tuesday, January 5, 2016

Fixed: Source Errior Installing .Net 3.5.1 with Windows 10

My customer had an issue installing .Net 3.5.1 on Windows 10 today.  The system is on an airgapped network and couldn't get to Windows Update to retrieve the source files.

The solution was to install the feature using Dism, and specify the DVD as the source media.  The command is:
Dism.exe /Online /Enable-Feature /FeatureName:NetFx3 /Source:D:\Sources\SxS