12 cell li-on discharged manually overnight to 0.00v (discharged across 10.6V path), after discharge the center 4 cells appear open and will not accept a charge, the 4 cells at either end charge satisfactorily. Seems weird that 4 cells (paralleled) would all open. Any ideas other than the discharge rate was too high? I will add that I first tried charging across the 10.6V path @ about 10.8V for a while. I was hoping to create a 'static' charge that would enable a normal charging via power adapter.

At no time did I notice heating of any of the 12 cells.

Many comments, thanks for all.

Clarification: The symptom is "Open" not "shorted", attempting to manually charge just this 4 cell section (3.6v) of the battery pack @ 3.8v results in no charge. The other 2 sections accept the charge just fine, or seem to at this point. Heat is not now, nor has it been an issue.

I think the information that there is built into the battery itself protection for "over" discharging fits, as the statement includes it can cause the battery to appear "open". The suggestion that only a battery analyzer could restore this battery (section) is interesting. Any idea as to what an analyzer would apply to this battery to bring back functionality? Lower,..higher voltage,.. pulsed dc,...?


closed as unclear what you're asking by Matt Young, Leon Heller, Nick Alexeev, Anindo Ghosh, Scott Seidman Jul 1 '13 at 10:36

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    \$\begingroup\$ Your description of the battery pack and discharge/recharge pathways and configuration could use a little more detail. Perhaps a diagram or schematic? You can use the built-in CircuitLab tool for this or link an image and I'll paste it in for you. Welcome! \$\endgroup\$ – DrFriedParts Jun 30 '13 at 17:22

12 cell li-on discharged manually overnight to 0.00v

It seems that was a bad idea.

If a lithium-ion battery is discharged below 2.5 volts per cell, a safety circuit built into the battery opens and the battery appears to be dead. The original charger will be of no use. Only battery analyzers with the boost function have a chance of recharging the battery.

Five tips for extending lithium-ion battery life

If the voltage of a lithium-ion cell drops below a certain level, it's ruined.

How Lithium-ion Batteries Work

Deep discharge may short-circuit the cell, in which case recharging would be unsafe.[citation needed] To reduce these risks, Lithium-ion battery packs contain fail-safe circuitry that shuts down the battery when its voltage is outside the safe range of 3–4.2 V per cell


Batteries should not be allowed to deep discharge. A battery can be deep discharged if a load is applied to it for an extended period of time. Deep discharging occurs when the capacity reaches 0%. There is protection circuitry in the device as well as in the battery that will reduce the chance of deep discharging, but not eliminate the possibility.


The protective circuit also limits the discharge voltage to between 2.7 and 3.0 volts per battery. In spite of these preventative measure, over discharge may still occur. If a lithium battery has dwindled to a voltage of less than 1.5 volts per battery, recharge should be avoided. Copper shunts may form inside the battery, causing a partial or total short circuit. In this case, the battery becomes unstable, charging the battery would cause excessive heat, and safety cannot be assured

Quest Batteries

The end-of-discharge voltage for lead acid is 1.75V/cell; nickel-based system is 1.00V/cell; and most Li-ion is 3.00V/cell. At this level, roughly 95 percent of the energy is spent and the voltage would drop rapidly if the discharge were to continue. To protect the battery from over-discharging, most devises prevent operation beyond the specified end-of-discharge voltage.

Battery University

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    \$\begingroup\$ Worse: In a pack, the stronger cells will reverse the polarity of the weaker cell when you go too close to zero volt. That will destroy the cell very quickly. \$\endgroup\$ – Turbo J Jun 30 '13 at 20:07
  • \$\begingroup\$ I think this about clears the mystery. The cells in question do measure a slight negative potential if allowed to rest for a few min. Time to order a replacement. On the good side I learned a bit about Li-ion batteries. I do wonder at how some posters (other forums) claimed success with totally discharging their units and recharging. \$\endgroup\$ – jeff_p Jul 1 '13 at 2:50

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