quick lipo balancing question

[E-HP]

Quick question for lipo users, since I'm still a novice. While monitoring my lipos, I noticed on one 6S pack that cell 1 is always 0.01V lower than the rest. While charging, cell 1 is about 0.02V higher than the others until the pack gets closer to fully charged. Cell resistance is the same across all cells at about 2.8 milliohms. What could be a technical reason for these observations, and is there anything I should be concerned about in the long run?

These Turnigy 6S 8Ah Graphene lipos. The packs will charge in under an hour, but it will take forever to balance that one cell (although I've only balance them twice).

 

[markz]

Cheap chargers like the Turnigy are not that accurate to measure 0.0xV delta changes.

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[E-HP]

Cheap chargers like the Turnigy are not that accurate to measure 0.0xV delta changes.

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Apologies, I should have mentioned the charger is a ISDT Q6 Pro. It goes to two decimals, but I calibrated it using my voltmeter that goes to 3 decimals.

 

[john61ct]

It is very common for vendors to deliver packs where the cells are not well matched.

Also for the devices they attach to, to cause them to wear unevenly over time, thus requiring greater / more frequent efforts to keep the pack balanced.

Never rely on what the device itself is telling you, many are not all that accurate to start with. Are you using a separate known good (even calibrated) instrument for these measurements?

It is also common for cell-level devices to not distribute V&A perfectly equally

and the power used by the devices' internal circuitry to not be pulled perfectly equally.

A good design may intelligently compensate for such "process inequality" so that everything is perfectly balanced at the end of the cycle.

So, I would focus on measuring the end state result, and only be concerned if that showed as consistently unequal.

Getting better balancing gear / methodology in place can lead to getting longer usable working lifespan out of worn packs, but

some focused more on performance than economy, feel it is better to just proactively retire them and buy replacements sooner.

 

[john61ct]

Also note, just because a device has a high resolution (goes to more digits on the display) does not mean it is more accurate (calibrated to reality)

 

[DogDipstick]

Are you using a parallel board?

Also note, just because a device has a high resolution (goes to more digits on the display) does not mean it is more accurate (calibrated to reality)

Resolution is typically 8 bit, 16 bit, or 32 bit.

Also, most hobby grade chargers charge to a tpaer of C/10... I can do C/20 labeled as an "accurate charge" with mine... or even any termination voltage... ( C/100, C/50, as specified in many ot the cells I like)