Li-ion 18650 salvaged from laptop

I had an old dead laptop and pulled the battery apart.

it was an 11.1 V 5400 Mah pack

I think I now have 9 Panasonic orange CGR18650HG, 3.7V 1800 Mah batts that need a charger...

Any input?

Do you think they are protected individually?

Re: Liion 18650 salvaged form laptop

BTW the pack has not been charged in about a year.

I DVM's them and 3 are at 2.4V the other 6 are at 3.68V

Re: Liion 18650 salvaged form laptop

Most laptop cells aren't protected individually - if there was a PC board in the pack, connected to every cell, that was the protection.
Still, not a big deal as long as basic precautions are taken. The DSD charger should do fine with these, though it'll take a few hours to charge them fully. The good part is, these are probably slimmer in diameter than protected cells, so they'll fit more lights.

The newer Ultrafire charger is interesting, as it's got 2 charging circuits, both at the same rate as the DSD. You can charge 2 cells in the DSD, but they share the current (as I understand it), so take twice as long. I believe the Ultrafire cuts off at a higher voltage as well, though my DSD terminates right at 4.20 volts.

Re: Liion 18650 salvaged form laptop

SKYWLKR said:

BTW the pack has not been charged in about a year.

I DVM's them and 3 are at 2.4V the other 6 are at 3.68V

Click to expand...

The 3.68's should be fine - no telling what their real capacity will be, as it drops with time in any li-ion. Still since they're all showing the same voltage, it's likely these are pretty even, and could be used in multiples.

The 2.4's may come back, though to be safe I'd mark them and only use them in single-cell applications. It's probable their capacity has dropped more than the others. I'd hate for one to reverse-charge on you and vent...

Re: Liion 18650 salvaged form laptop

Any links to this charger? I would rather the lower voltage cut off...

Re: Liion 18650 salvaged form laptop

I saw a thread where a Lipo charger was mentioned...

I have a 1-3 cell lipo charger, would it work for the Li-ions?

I would build a spring loaded or may magnet tip charger interface

I salvaged another pack

this one is mostly unmarked cells but there are 8 to power a 14.4 pack to 2700Mah

I'm guessing they are 3.6@ 1350's Li-Ions

are they worth using?

I probably going to use them seriesed 3 X 2 sticks for a Hot-wire mag mod and used singly in a scratch built single cell LED.

so I have 9 1850 and 8 1350's... now I just need to figure out a charger.

will the li-po unit work?

Hello SKYWLKR,

Li-Ion and Li-Ion Polymer cells utilize the same charge limits, currents, and voltage limits. Your Li-Po charger will work fine as long as your cells stay in balance.

Tom

I will be doing them mostly individually.
But,
Can I charge them parallel? I am thinking of making a charging tray for them to hold 2-4 cells so they charge at the same time at a half ,2/3 or 1/4 the current to each but charged at the same time.

OR

Should I charge them in series 1-3 cells(using as closely matched cells as possibly)? It CAN auto detect 1-3 cells for li-po automatically!

I can set the charger to 500, 1000 and 1500 Mah can both of those cells handle 1000 Mah?

I think it's a Hobby fly charger.

Hello SKYWLKR,

Parallel charging is an excellent idea. You choose a current that does not exceed the 1C maximum rate for the lowest capacity cell.

For example, if you hooked up a 1800 mAh capacity cell with a 1300 mAh cell, the maximum charge rate you could use would be 2600 mA to keep at or below the 1C rate of 1300 mA for the smaller capacity cell.

Tom

If I parrelled 1 each the 1350 and 1850 (is that what you are saying?)how would the charger know when to stop?

Seems like it would stop when it sensed the 1350 reach peak voltage and then stop...

I would have thought to keep the capacity as close as possible esp when parallel charging else end up with uncharged batteries.

The max rate of the charger is 1500Mah

the quickest way to charge 3 cells would be to line up 3 cell +-,+-,+- and charge them like that.

could the 1350 suport that C rate?

here is the charger, seems it 250,500 and 1000 rates.

The manual says that it's not compatible with Li Ion...

Hello SKYWLKR,

Li-Ion cells stop at 4.2 volts, regardless of capacity.

When you parallel Li-Ion cells, they equalize. NiMh and NiCd cells do not do this, or only do it in voltage, but not capacity. Li-Ion cells are different.

You can charge cells in series, but it is more dangerous, unless you have an active balancing circuit to insure that each cell does not go above 4.200 volts.

The first Li-Ion cells that came out were only charged to 4.1 volts. I don't believe any of these early cells are still in existence. All current Li-Ion cells can be charged to the same levels as Li-Ion Polymer cells. The older Li-Ion cells could handle charging to 4.200 volts, but cycle life would be reduced. There was not a safety issue with this level of charge.

It sounds like you need to take some time and think about, and figure out how parallel circuits work and what you can expect from parallel and serial battery packs. Once you have a working knowledge of that, charging currents and maximum current draw will become clear. Until then, I would recommend single cell charging.

Let me see if I can get you started...

When you parallel cells, the voltage stays the same and the capacity is added together. This means that if you were to parallel your 1800 and your 1300 mAh cells, you would end up with a 4.2 volt battery (a battery is made up of 1 or more cells) with a capacity of 3100 mAh. A 1C charge for this battery would be 3100 mA, with 1550 ma going to each cell. Since 1550 mA is greater than a 1C charge rate for the 1300 mAh cell, you should not charge at this high a rate. The highest rate you should use is 2600 mA. It is OK to go below that, so it looks like you would be charging at 1000 mA, or whatever the maximum charge rate is for your charger.

If you go back to a single cell, everything gets easy. 1C is the capacity of the cell.

Now, if you hook your 1800 mAh cells in series, you end up with a 8.4 volt battery that has a capacity of 1800 mAh. The maximum charge rate would be 1800 mA and your voltage would terminate at 8.4 volts.

Now, lets put 3 of your 1800 mAh cells in series. Let's also say that they are used cells and may not be well balanced. Now we have a situation where the maximum voltage we are charging to is going to be 12.6 volts, but this is going to be made up from 3 cells. If all 3 cells end up at 4.200 volts, we are good to go. However, if there is some build up of internal resistance of one cell, we could end up with the 3 cells at 4.2, 3.9, and 4.5 volts. This still totals up to 12.6 volts, but the cell at 4.5 volts is overcharged and could be close to rapidly venting with flame. This is the problem with charging Li-Ion cells in series. The advanced Li-Ion/Poly chargers have balancing taps that allow for cell balancing during the charge. If one cell gets above 4.2 volts, the charge is shut off from that cell to keep it from overcharging.

You can avoid all of this worry of overcharging by charging in parallel, or charging each cell individually.

Tom