Li-Ion from old computer batteries

[GHA]

Anyone played with this?
I ripped open a dead Toshiba 19v battery earlier , looked like 6 x 18650 Li-Ions inside. So the stupidly optimistic hope is that just one cell was dud and I can use the other ones and save money and feel clever

So one cell is one charge, dc supply is set to limit voltage to 4.45v which with the losses along the croc clip leads ends up as about 4.1v and current limited to 2.2A.
This particular cell seems to be accepting a couple of amps and nothing is getting too hot... Yet ..

Any thoughts?

Edit: Maybe bit much, cell is getting quite warm, current backed off to 1A. For now, which is 4.038v at batt terminals.

 

[William_H]

In my experience these Li-ion cells are fairly easy to kill. I would limit the voltage to 4.1 and limit the current to perhaps .2 ma. I presume you ar ein no hurry to charge the battery.
I use a 330 ohm resistor in series with the cell from a 12v supply. Gives about 20ma charge. so not much over heating. I have a TL 431 "adjustable zener" wired across the cell to start conductiing at 4.1 volts. So charge voltage never exceeds that. Seems to charge the cells slowly but safely.
Do watch that temperature as they can ignite I understand. Yes you would hope that some cells from the computer battery are still OK. good luck olewill

 

[grumpy_o_g]

In my experience these Li-ion cells are fairly easy to kill. I would limit the voltage to 4.1 and limit the current to perhaps .2 ma. I presume you ar ein no hurry to charge the battery.
I use a 330 ohm resistor in series with the cell from a 12v supply. Gives about 20ma charge. so not much over heating. I have a TL 431 "adjustable zener" wired across the cell to start conductiing at 4.1 volts. So charge voltage never exceeds that. Seems to charge the cells slowly but safely.
Do watch that temperature as they can ignite I understand. Yes you would hope that some cells from the computer battery are still OK. good luck olewill

+1

Li-Ion charging circuits and the batteries are often very carefully tailored to meet the exact requirements and the results can be a bit nasty if you get it wrong. As long as you are simply replacing one cell instead of the entire battery and using the battery in the laptop you'll be fine if the other cells aren't too knackered. If you're not using the laptop charging circuit I'd recommend trying to find the exact charging regime for that cell and knocking up a circuit to reproduce it.

 

[nimbusgb]

If one cell is knackered the others will be close behind. They have a limited lifespan even if not used. Easier to just replace all the cells and responsibly dispose of the old ones.

 

[nigelmercier]

Anyone played with this?

Personally I prefer to use these...

 

[pyrojames]

Personally I prefer to use these...

excellent!

 

[charles_reed]

At least the resulting fire won't be down to terrorists' home bomb-making or to runaway marijuana production.
As a precaution the OP should warn local plod what he's doing - doubt his home insurance will be pleased.

 

[GHA]

Personally I prefer to use these...

I prefer looking a bit deeper into the subject

http://batteryuniversity.com/learn/article/charging_lithium_ion_batteries

Need to figure out a capacity test now to see if there's any life left.

 

[GHA]

In my experience these Li-ion cells are fairly easy to kill. I would limit the voltage to 4.1 and limit the current to perhaps .2 ma. I presume you ar ein no hurry to charge the battery.
I use a 330 ohm resistor in series with the cell from a 12v supply. Gives about 20ma charge. so not much over heating. I have a TL 431 "adjustable zener" wired across the cell to start conductiing at 4.1 volts. So charge voltage never exceeds that. Seems to charge the cells slowly but safely.
Do watch that temperature as they can ignite I understand. Yes you would hope that some cells from the computer battery are still OK. good luck olewill

As most 18650 seem to be at least 2000 mAh that's 5 days to recharge.

Edit:
Found the datasheet for these ones, http://www.meircell.co.il/files/Sanyo UR18650A.pdf
Charge voltage - 4.2v
charge current - 1505mA.

 

[TQA]

Please take more care. At the very least place the charging battery in something fireproof. Nomex sacks and old ammo boxes are what we use but a cooking pot with lid works.

I am part of the model flying fraternity and we have had numerous instances of fires while charging lithium batteries. This was the result of charging on the kitchen worktop in a RV. He was lucky not lose the RV and several thousand pounds worth of models.

View attachment 48209

The above incident occurred even though an advanced type of charger was in use where the voltage of each individual cell was monitored and the charge rate varied automatically and most importantly there was a thermal sensor. Even so the pack went up.

 

[GHA]

I am part of the model flying fraternity and we have had numerous instances of fires while charging lithium batteries.

Interesting. Wonder what's different in the charging regime which causes this while what must be 10's of millions of laptops running on lithium ion seem largely unaffected. Maybe laptops have much more cautious parameters for charging. Anyway I suspect these ones are not in the greatest of health, internal resistance seems too high. Haven't done a capacity test yet, so they might come in useful.

 

[Beyondhelp]

Interesting. Wonder what's different in the charging regime which causes this while what must be 10's of millions of laptops running on lithium ion seem largely unaffected. Maybe laptops have much more cautious parameters for charging. Anyway I suspect these ones are not in the greatest of health, internal resistance seems too high. Haven't done a capacity test yet, so they might come in useful.

I'd say that almost exactly. Model batteries are also far higher stressed/used/abused. I suspect that the faults develop whilst in use and show up later whilst on charge. As energy densities get greater the potential for damage from fires will only get worse.

Quite interesting stuff really. When EV cars get ever more popular there are going to be some really really nasty fires from them.

 

[noelex]

I would also urge caution

The 18650 batteries purchased for torches etc are protected cells (or they should be). Although it cannot be seen they have a small circuit board over the + end.

Computer batteries have a global protection circuit board. When you remove the cells you are using unprotected 18650 cells, which is not a good idea. To charge unprotected 18650 batteries without a proper lithium charger is further increasing the possibility of problems.

 

[William_H]

For a capacity test for NIMH cells I use an old analogue crystal electronic clock that runs on 1.5v cell. You just run the clock on the battery to be tested. Fit a discharge resistor in shunt (parallel) with the battery and clock to give a known discharge current. Set the clock to 12 PM then start it running. The clock will stop when the cell is low at about .8 volt.
I imagine this idea will also run down a Li-ion cell. Use a voltatge divider resistors to run the clock and an electrolytic capacitor across the clock to provide pulsed current.
good luck olewill

 

[noelex]

For a capacity test for NIMH cells I use an old analogue crystal electronic clock that runs on 1.5v cell. You just run the clock on the battery to be tested. Fit a discharge resistor in shunt (parallel) with the battery and clock to give a known discharge current. Set the clock to 12 PM then start it running. The clock will stop when the cell is low at about .8 volt.
I imagine this idea will also run down a Li-ion cell.

That is fine for NiMH but not OK for Lithium. Lithium battery are quickly and rapidly damaged by low voltage. To measure capacity you need a very precise voltage cutoff, much higher than 0.8v. The battery needs to be immediately charged.

The hobby chargers will do this for you. You can adjust the final cut off voltage they will count the capacity and display it mHrs. They will then automatically charge the battery. There are settings for virtually every battery type number of cells etc.

See an article here:
http://lygte-info.dk/info/HobbyChargers UK.html

The cheaper hobby chargers which are fine for occasional use are not expensive.

 

[nigelmercier]

This looks handy for battery capacity testing: http://amzn.to/1D9AlKg

Note that a lot of people who buy such devices, and chargers, also buy a fireproof charging bag: http://amzn.to/1vRBiym

 

[GHA]

This looks handy for battery capacity testing: http://amzn.to/1D9AlKg

Note that a lot of people who buy such devices, and chargers, also buy a fireproof charging bag: http://amzn.to/1vRBiym

Or use and arduino with sd card, which it's doing now though a 6.8Ohm resistor.
Will manually turn off when it gets down to about 2.8v, but it would be easy to get the arduino to turn off a relay or transistor, just playing around today.
And nolex is right about the circuit board, these ones almost certainly won't have one , charging isn't too great a prob but having to be careful not to discharge too much probably puts these particular cells in the play around then throw out category.


Not sure my laptop will fit in that bag when it's charging

 

[GHA]

Bit of life left in them but not much..

Voltage was logged once a second (Actually, might have messed up a tiny bit, there was a 1 second delay programmed but might have been a few milliseconds while the arduino did its' thing as well as the delay)
Y axis is millivolts.X is time. Red line at bottom is amps.
Current calced at voltage/resistance, measured as 7ohms. Then added up the current each second divided by 60 twice to go from miili amp seconds to mAh. Total came out at just over 1000mAh, should be 2250mAh when new.
So stuffed
Graph here.
https://plot.ly/~Paddyb/14/col2-vs-col4/

All good fun

 

[noelex]

Cool graph

There are some great lithium 18650 batteries available and there are some really **** batteries.

AW are an example of the former. Ultrafire are an example of the latter. Ignore the rated capacity and concentrate on the independent tests.

For use on a boat the AW IMR batteries are worth considering. These have a slightly lower capacity but have a different chemistry and are very unlikely to explode and burn if charged incorrectly.

They are superior, in almost every way, to the best NiMH batteries and almost as safe.

Despite the above I still have a soft spot for Eneloop batteries. They have a great cycle life. I still have some that are 6 years old and have used once a week and they test at 95 % rated capacity.

 

[GHA]

Cool graph

There are some great lithium 18650 batteries available and there are some really **** batteries.

AW are an example of the former. Ultrafire are an example of the latter. Ignore the rated capacity and concentrate on the independent tests.

For use on a boat the AW IMR batteries are worth considering. These have a slightly lower capacity but have a different chemistry and are very unlikely to explode and burn if charged incorrectly.

They are superior, in almost every way, to the best NiMH batteries and almost as safe.

Despite the above I still have a soft spot for Eneloop batteries. They have a great cycle life. I still have some that are 6 years old and have used once a week and they test at 95 % rated capacity.

Another big fan of eneloops here, excellent youtube channel..