Warning: Turnigy chargers' JST-XH balance adaptors
Posted: Sun Aug 12, 2012 9:20 pmThese balance adaptors are supplied with many of Hobbyking's chargers. I suggest you carefully throw yours in the bin if it's anything like mine.
I was reasonably happy with my Mega 400W V2 until a random check with a voltmeter showed it indicating 1V below the true values for the first two cells whilst charging a 6S pack.
After much head-scratching, I finally removed the plastic XH sockets from the adaptor board. Everything suddenly became clear:
As you can see, the flow soldering is so poor that few of the pins are attached to the traces at all. In this state the current passes around the pins through the narrowest part of the traces, vapourising them. A continuity test showed the charge lead was no longer connected, and 2 of the balance lead pins were open-circuit too.
Perhaps even more worringly, the charger was happily continuing to raise this pack (effectively now a 4S pack plugged into the highest pins of the balance port) pack to a 6S full charge via the 5 remaining pins on the balance port alone. With so many other failsafes on these iMax B6-alikes, I'm disappointed it didn't spot a problem this obvious.
I'm think there's a strong chance this would have caused a fire had I not intervened. Be careful, folks.
I was reasonably happy with my Mega 400W V2 until a random check with a voltmeter showed it indicating 1V below the true values for the first two cells whilst charging a 6S pack.
After much head-scratching, I finally removed the plastic XH sockets from the adaptor board. Everything suddenly became clear:
- Dangerously poor soldering on a JST-XH balance adaptor
- 2S-6S adaptor crop2.JPG (199.86 KiB) Viewed 10625 times
As you can see, the flow soldering is so poor that few of the pins are attached to the traces at all. In this state the current passes around the pins through the narrowest part of the traces, vapourising them. A continuity test showed the charge lead was no longer connected, and 2 of the balance lead pins were open-circuit too.
Perhaps even more worringly, the charger was happily continuing to raise this pack (effectively now a 4S pack plugged into the highest pins of the balance port) pack to a 6S full charge via the 5 remaining pins on the balance port alone. With so many other failsafes on these iMax B6-alikes, I'm disappointed it didn't spot a problem this obvious.
I'm think there's a strong chance this would have caused a fire had I not intervened. Be careful, folks.