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March 25, 2019, 03:56:55 AM

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Author Topic: Battery Pack Voltage Instability?  (Read 540 times)

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Offline Bad Raven

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Battery Pack Voltage Instability?
« on: June 19, 2018, 15:50:15 PM »
Through getting into Quads a while back, I have been running all my LiPo with a screamer alarm fitted to the balance plug. Found it's better than wired in sensors, annoying your flying neighbour with Tx call outs or looking at Telemetry screens. Can hear these at range even if an engine powered plane is running close to.

However, a very few packs exhibit strange behaviour I do not understand.

What happens is seemingly random one off operation of the alarm, which presumably means the alarm has sensed a dip below the set voltage. I usually set for 3.6v per cell.

Yet:-

1. The pack is balanced before and still perfectly reasonably so after use.
2. The pack runs for the expected time before the alarm triggers "properly", with normal capacity and power.
3. Impedance measurement shows nothing untoward.
4. The trigger is not linked to a likely reason such as a throttle opening or other obvious battery sapping motor loading, like a sudden climb.
5. Several packs of differing size do this, and with more than one alarm unit, but only a few packs out of many.

One 6S 4000mAh pack was today random single triggering within five seconds of starting a flight (500 Heli), maybe one bleep per 30 seconds.  This ONLY on light current drain, with NO operation during punch outs, 3D moves, etc.   It ran for the normal time with no other symptoms before increasingly starting to trigger "on load" as might be expected.

Back home on the bigger ISDT tester and then charger it shows normal measurements and capacity taken to recharge.

The only thing I can think of is the balance plug contacts are not stable.

 $%&

The user formerly know as Bravedan........... Well if Prince can do it....................


 

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