Hearacy? LiIon cells not damaged by discharge to zero?

Gauss163

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The youtube video was a waste of 15 minutes. The author does not have a good understanding of the implications of the results of the study, e.g. he wrongly tries to extrapolate the results to cells that have been stored for a long time at very low voltages - which is not something that was tested in the study.
 

Crazyeddiethefirst

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I have had a few cells that show up as -0.1 or -0.2volts on my dmm, but they actually had just had the protection circuit tripped(why they don't read 0.0 I'm not sure. After 20 seconds in a good charger, they suddenly show 4.18 to 4.20volts & work just fine...
 

Gauss163

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I have had a few cells that show up as -0.1 or -0.2volts on my dmm, but they actually had just had the protection circuit tripped(why they don't read 0.0 I'm not sure. After 20 seconds in a good charger, they suddenly show 4.18 to 4.20volts & work just fine...

That they survived a few charges implies very little about their long-term safety.
 

CuriousOne

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I have disassembled a lot of laptop battery packs for cells, and a lot of them were below 2v and close to zero. I have done tests using about 200 batteries from various manufacturers. Capacities all were 2000-2200mAh. The worst cells to recover were Sanyo UR18650's, they almost never recover, or get very little capacity. Samsung ICR18650-22FU were 50/50, may work, may not. Sony SF18650GR were amongst the best, able to recover in 90% cases.
 

Overclocker

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i've discharged many cells down to 1.0v. stayed there for a few mins. then charged back up again. no change in capacity and DC IR as tested w/ iCharger 106B+ w/ low-resistance connections

so no it's not catastrophic as most people think but of course long-term effects are unknown
 

HKJ

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i've discharged many cells down to 1.0v. stayed there for a few mins. then charged back up again. no change in capacity and DC IR as tested w/ iCharger 106B+ w/ low-resistance connections

so no it's not catastrophic as most people think but of course long-term effects are unknown

I take a look at manufacturer recommendations/warnings here: http://lygte-info.dk/info/BatteryLowVoltage UK.html

1V is not that far from the absolute minimum.
 

Gauss163

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I take a look at manufacturer recommendations/warnings here: http://lygte-info.dk/info/BatteryLowVoltage UK.html

While some info can be gleaned from such general remarks in datasheets, such information yields only a very coarse guide on such matters. The problem is that there are such a large variety of chemistries and designs, that it is difficult if not impossible to make general recommendations (unless they are ultra-conservative).

If you peruse the patent filings from major manufacturers you will find that they have all been working on enhancements that protect against damage from overdischarge (iirc Sanyo even once claimed that they hoped to achieve 100% protection in future designs). Unfortunately we don't know how much success they had, and which models implement such enhancements, since most of this information is highly proprietary.

As such, it is best to be cautious with highly overdischarged cells, esp. older cells (e.g. laptop pulls) which are much more likely not to implement pertinent saftey enhancements.
 
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