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Li-Ion Battery Problem

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rahulshah

New Member
I have got few Li-Ion Batteries which shows 0 voltage when measured with a multimeter. When I asked the shop-keeper, he told that they are fully discharged and needs to be charged and then they will work fine. But Yesterday I read in one article that its not advised and not safe to charge a fully discharged Li-Ion battery.

Should I go for charging those batteries?:confused:
 

MrAl

Well-Known Member
Most Helpful Member
Hello there,


Everything i have read over the years say that an Li-ion cell that has a voltage
that falls below 2.5v should NOT be charged again due to problems that come up
inside the cell which could cause it to explode or start on fire.
Even so, if you do charge it and it doesnt blow up the capacity will probably still
be much less than it should be.
All this leads me to advise you to bring the cells back and tell the seller that he is
selling bad Li-ion cells! If he doesnt believe you or insists that they are good
anyway, im sure we can find many web sites that talk about this problem.

I once charged a cell that was around 2.4v before i knew about this problem,
and it did take a charge and didnt blow up but the capacity was wayyyy
lower than it should have been for that size cell, so it was not worth doing
in the first place. It's been thrown out since then.

A cell that shows zero volts has got to be really bad. Most cells that are shipped
these days have around 50 percent charge until they are recharged, which
means their terminal voltage would be above 3 volts at the least.
 
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HotSolder

New Member
Hello,

Many Lithium battery packs have built in protection that prevents deep discharge. When testing a Varta battery pack I would ofter see the circuit protection kick in and disconnect the battery, when measuring the voltage across the terminals it would often be very low (never 0 V though), especially if using a cheap multi meter. The battery would remain in this state until a charge cycle was initiated. It is a possibility that the battery pack you are measuring has the same feature. To be on the safe side, could you not go back to the shop and just swap the battery?

Regards

Iain
 

giftiger_wunsch

New Member
Out of interest, were these batteries showing 0V when brand new, or have these been laying around for a while? Either way, I doubt you'd get anywhere at all trying to charge those batteries even if you managed to avoid them catching fire or other nasty effects. I've had plenty of batteries reading very low voltages (such as 200-400mV) but I've never tested a battery and been unable to get a voltage reading out of it at all. Those batteries are well and truly dead.
 

HiTech

Well-Known Member
Li-Ion batteries are known for their extended shelf-life. Look on the batteries for a mfgr-ing date. You may be able to use that in your argument for an exchange or refund. If you do opt for an exchange, bring along a voltmeter and test them right in the store before leaving.

I too have experienced the same thing as MrAl mentions regarding charging a near dead Li-Ion cell. The capacity was way lower, practically eliminating any reliable use of it.
 
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mneary

New Member
Has not been clarified if this is a battery oack with internal protection or a standalone cell?

If it's a battery pack, what does one see at the terminals when the protection circuit decides you must put more in before it lets any more power out? Do you see a voltage, and if so, how?
 
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RCinFLA

Well-Known Member
Safety circuits disconnect battery below 2.5v to prevent futher discharging LiIon battery.

If the cells have dwelled at 1.5V/cell and lower for a few days a recharge should be avoided. Copper shunts may have formed inside the cells, leading a partial or total electrical short. The cell becomes unstable. Charging such a battery would cause excessive heat and safety could not be assured.
 
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