Laptop battery has been fully discharged, any idea to wake it up?

[Willen]

Due to few days of power short (VRM was shorted), the battery has been fullly discharged than safe zone. While booting laptop it shows some warining like- "battery is very low than........ replace another...."

Before shorting power section battery was very good and backup was 2 hours. During shorting its all power was consumed!

Then please help me now- How can I recover the battery. Will simple long charge (on laptop) help me? I charged almost 3 hours but it is not working!

 

[ChrisP58]

If the battery management system in the pack has decided that the battery has failed, it wont even allow itself to be charged. If that is the case then you either replace it, or go inside the pack and repair it. What repair is needed will depend on which fail mode caused the shutdown.

Please post the full text of the error message. Also the make and model of the laptop and battery pack.

 

[tcmtech]

Sometimes they battery can be jump started back to life by manually charging it which depending on the battery may only need it to have two leads attached to on its main connector and a current limited power source attached to bring the battery cells up to a high enough charge for the system to restart.

Or the pack has to be opened and the leads tied into inside the battery pack.

 

[Pommie]

I had a Galaxy Tab that had the same problem. After days of trying to charge it I gave up but still left it connected. After about 1 week it had finally got a charge and is now fine again. That was about 6 months ago and it's still going fine. The only thing I can think is that the monitoring circuit somehow trickle charges it and that was enough.

An alternative might be to bypass the charge circuit and charge it with a very low current over many days to try and get it back to a chargeable voltage.

Mike.

 

[4pyros]

Yes I think it may need to slowly be brought back to life.

 

[audioguru]

A laptop computer uses a Lithium rechargeable battery. It is destroyed if the voltage of a cell drops below 3V and is weakened if the voltage of a cell drops below 3.2V.
If you try to charge it then its protection circuit should prevent charging so that IT DOES NOT CATCH ON FIRE!

 

[4pyros]

How to Awaken Sleeping Li-ion
Li-ion batteries contain a protection circuit that shields the battery against abuse. This important safeguard has the disadvantage of turning the battery off if over-discharged, and storing a discharged battery for any length of time can do this. The self-discharge during storage gradually lowers the voltage of a battery that is already discharged; the protection circuit will eventually cut off between 2.20 and 2.90V/cell.

Some battery chargers and analyzers, including those made by Cadex, feature a wake-up feature or “boost” to reactivate and charge batteries that have fallen asleep. Without this feature, a charger would render these batteries as unserviceable and the packs would be discarded. The boost feature applies a small charge current to first activate the protection circuit and then commence with a normal charge.

Do not boot lithium-based batteries back to life that have dwelled below 1.5V/cell for a week or longer. Copper shunts may have formed inside the cells that can lead to a partial or total electrical short. When recharging, such a cell might become unstable, causing excessive heat or showing other anomalies. The “boost” function by Cadex halts the charge if the voltage does not rise normally.

Figure 1: Sleep mode of a lithium-ion battery

Some over-discharged batteries can be “boosted” to life again. Discard pack if the voltage does not rise to a normal level within a minute while on boost.

A study done by Cadex to examine failed batteries reveals that three out of ten batteries are removed from service due to over-discharge. Furthermore, 90 percent of returned batteries have no fault or can easily be serviced. Lack of test devices at the customer service level is in part to blame for the high exchange rate. Refurbishing batteries saves money and protects the environment.

 

[4pyros]

Some say that freezing a Lithium can help it take a charge agan but I dont think it was ever proven so tack it with a gain of salt.

 

[audioguru]

Maybe the battery was missing a protection circuit or maybe the protection circuit is defective.
All laptop computers I have seen simply stop when the battery voltage gets low but it is not too low and can be charged again over and over.

 

[Willen]

...Please post the full text of the error message. Also the make and model of the laptop and battery pack.

Thank you but my laptop is with mechanics. After return back I will post the message sure.


um some hope rised.

I want to deassemble the battery but never done before. It is HP. Looks like is shielded so I have to cut its pack. Isn't it? Or some hidden screws or hidden locks?

 

[tcmtech]

The easiest way to open them is with a Dremel and cut off disks. Just zip the seam open where its glued together.

 

[Willen]

I have no special tools, I have local n common tools like knife instead. Did you mean I have to crack its shield (glued pack) to open battery pack? If we did so then can we able to fit battery again for laptop? Won't its housing damaged?

 

[4pyros]

I have no special tools, I have local n common tools like knife instead. Did you mean I have to crack its shield (glued pack) to open battery pack? If we did so then can we able to fit battery again for laptop? Won't its housing damaged?

Yes without the right tools you may damage the pack.

 

[Menticol]

Some years ago I've dismantled my laptop's battery in an attempt to refurbish it. I took some photos of the procedure. But I should warn you that I failed, and chances of succeeding aren't very good after all.

On my case I found that one of the cells was dead and the others were good. Replacing the dead cell made no difference because the "Smart Battery" chip already had decided to lock the whole pack. Watching it in retrospective that was a fortunate thing because mixing old with new batteries is a bad practice.

As Audioguru said, tampering with batteries can result on very fiery fires. The DIY spirit is great, but in this case it's not worth the risk.

By the way now that I mentioned tampering, I have read on a forum that some Smart Battery chips are designed to lock the whole battery if one of the cells is disconnected. I can't confirm or deny this.

 

[tcmtech]

I rebuilt one of my battery packs a few years ago without any real problems.

What I found out was that if the battery protection module was left disconnected from everything for a few days it would reset and accept the new cells without problem. Or at least that works with the old battery systems like my old laptop had.

 

[audioguru]

I used the Li-ion battery cells (without the protection circuit) from a laptop battery in an electric model airplane. The battery got hot just like the motor.
Normal Li-po battery cells usually used in electric model airplanes do not get hot and supply much higher power.

 

[Menticol]

What I found out was that if the battery protection module was left disconnected from everything for a few days it would reset and accept the new cells without problem. Or at least that works with the old battery systems like my old laptop had.

Great, now I will not be able to sleep thinking of dismantling that battery again

 

[tcmtech]

Well you got a 50/50 chance of it working and a 100% justifiable excuse to buy a basic Dremel tool set!

 

[Menticol]

Ha, I caught your pun in midair!

I already have a Dremel but using it for this application is a bad idea. The disks I have are relatively thick and keeping the dremel in a perfect straight line is very hard. Chances are that the battery case will never join together again. Also take in account that the dremel will not forgive you if you miss the depth, cutting trough the cell like butter.

But I agree with you, the box cutter catching fire was very unprofessional, I'll try one with metal handle

Somebody told me that the best technique to open plastic cases is filling the voids with gasoline or a solvent and letting it sit for 10 minutes. I'm not brave enough to try it

 

[tcmtech]

I think you are way over thinking it. I do fine plastic cutting with my dremel all the time. All you are doing is making a slit in the plastic with a cutoff wheel. Not sawing the whole thing in half.

You just need to put the battery in a vice or have a solid way of holding it on edge and the rest is just simple two handed cutting which with a little practice a dremel and a good cut off wheel can make a cut that is no deeper than a sheet of paper is thick.