Battery cells replaced, charge rate is very low

All,
My acer travelmate battery was giving only 10 mins running time after a life of ~ 3 years. Instead of going for a new battery for an old notebook, I decided to replace battery cells.
I opened up battery pack and found 4 cells, Li ion, 3.7 V, 2200 mAh, make sony. In market I got 4 cells, 3.7 V, 1800 mAh at 12 $ total. I found it v difficult to solder these cells but managed. Battery output as measured on multimeter was 16 V.
After placing battery back and charging, it was charging at very slow rate, after 8 hours it approaches 0.3 % and then at once to 100 %. It gave me 3 mints time and then to zero.
I decided to drain battery completely and connected it to 12V bulb, left for overnight and checked in morning the voltages were 0.7 V.
Now I am charging for the last 3 days, it has approached 1.1 % only, charge rate is v less, 103 mw (as measured on batterymon). I used another charger but same problem, any suggestion..?

 

You might have ruined a battery cell with the soldering......

 

Like I mentioned, after repacking the battery, voltages were 16 V. Each cell giving ~ 4 V, so all cells were contributing after soldering.

 

Most modern laptop batteries have additional power control circuitry in addition to the battery cells. By replacing the original cells with different capacity cells, you might be confusing the power control circuitry and thus it's trying to charge the new cells to the capacities and specifications of the old ones, which might have ended up damaging your new cells.

 

Yes, there is additional circuit in the battery. And the new cells are of slightly less mAh, but notebook is old, I want to do more experiments with it. Any idea if I can recharge the cells separately by taking out of the batteyr?
OEM are again earning money by offering new battery for say 80-100 $, they'll never sell batteries with option of replacing cells just to make fool many of us who contribute to their yearly earnings.

 

You can try, I suppose, but I don't know that it will do any good. In a way it's kind of like trying to run a gasoline car on diesel. It might work for a little while, but depending on exactly how the engine is designed, there's a good chance you're going to break something.

 

so far, in comparison to the time and money you've spent on creating a bad battery, those OEM replacements are starting to look more reasonable.

The symptoms that you describe are indicative of a bad cell. Not holding charge for more than a few seconds after hours of charging.

 

Agreed with newposter.. firstly , doing this is dangerous and looks like u have made some error in the process... I strongly recommend u get a new OEM battery ... before this experiment blows up ur laptop and maybe kills u.

 

So far what I know is Li ion battery has its own internal circuit for the protection, then their is the charging circuit of the notebook itself, helping to avoid any explosion etc
Li ion cells do have a remote possibility of exploding, if some impurity is present inside the cell.
Still playing with Li-ion cells is tricky, and one must be v careful.
I haven't seen anyone who has done the same on this forum and who can shed some light on charging circuits and the actual problem.
I am thinking to go to the shop where I purchased the cell, they came with 6 months warranty, also the guy there also repack notebook batteries, I'll ask him to do this for me.

 

I too think you've spent too much time and money on this compared to just getting another battery.

What your description of the problem sounds like to me is that you've either damaged the protection/charging circuit inside and/or outside the battery or you've replaced the cells with much different characteristics than the originals had.

Either way, I can't see this working, ever. I have talked to 'battery' people that refuse to work on Li Ion cells because they didn't have the proper tools. Seems like not only do you not have the proper tools, you also don't have the proper (safety) knowledge either.

I hope nobody else is tempted to go down the route you have.

Good luck in your situation, I really mean it.

Cheers!

 

When rebuilding battery packs, the replacement cells need to be the exact volt and amperage as the originals. Additionally, the temp curves and charge/discharge numbers need to be a match. This is not a negotiable or ideal situation, it is pretty much mandatory. This is so that the charge and protective circuits inside of the battery pack will work as expected.

On top of this, avoid soldering anything lithium. It is trivially easy to overheat a cell and/or to destroy the seals at either end of a cell. This is why competent rebuilders use cells that have factory installed solder tabs.

A lithium cell that blows its seal is merely annoying and only a 'little bit' dangerous. A lithium cell that has been heat damaged, has it's internal structure warped, and then blows a seal is toxic and can easily catch fire.

Caution.