Sunday, January 31, 2016

Parallel LiPo Battery Charging

I have been charging my batteries sequentially until recently.  I saw some discussion on the Hardcore FPV Racing thread on parallel charging.  Parallel charging is where several batteries can be charged simultaneously.  There's a great video on YouTube that gave me the idea.

The gear featured in the video is the following.

Turnigy Accucel-6 50W 6-cell balance charger, from HobbyKing
RMRC Parallel Charging Board - 35A XT-60, from RMRC

If you purchase these components they will connect up no problems.  There are a couple of rules for charging.

  • You can only charge a single type of battery per charger.  In my example photo, I could add 2 more 4s batteries.  Don't mix 3s and 4s batteries on the same charger.  Of course, you can run a 2nd charger if your power supply support it and charge 3s on that charger.
  • Make sure each battery is discharged to around the same level.  Don't connect a fresh and a dead battery or something strange like that.  The Paraboard has thermal protection but it's best if you observe this rule
  • To charge at 1C multiply the number of batteries charged by the mA rating.  In my example photo, my batteries are 1800mA and I am charging 2 batteries so I set my charger for 1800mA x 2 = 3600mA, charging 4 is 1800 x 4, etc.  Of course, make sure your power supply and charger can source the current.

For my project, and unlike the video I provided, I had a iCharge 208B on hand.   The iCharger 208B is great charger and supports up to 8s batteries.  Unfortunately, RMRC's Paraboard does not plug directly into my charger out of the box.  To get it working you have to pop the pins out of the 6-cell Molex connector into a the 8s connector that was supplied with the iCharge 208B.  To pop them out slide a small screw driver under the Molex pins as shown and give the wire behind a tug.  It should come out easily.  Plug each wire from the Paraboard into the corresponding numbered cell on the iCharge 208B side.  When your done there will be two pins unused (cell 7 and cell 8).

Before you begin charging, plug you batteries balance port into the Paraboard.  You should see the voltage readings on your charger and a red LED on the Paraboard blinks.  If you don't something is up with your wiring.  Always supervise your batteries while charging.

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