Salvaging old Notebook battery

Started by CroPrepper, April 09, 2018, 08:21:43 am

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CroPrepper

Hi,

I just found an old notebook battery in my cellar and decided to give it a try. I was able to salvage 8 x 18650 cells. 6 are still on 3.71V, 2 are on 2.1V unfortunately.
After googling I found out that those are 2600mAh cells. Pretty neat!

https://sep.yimg.com/ty/cdn/theshorelinemarket/LG-18650-2600.pdf

Is there a way to revive those cells on 2.1V or are they gone?

I think about a 3s2p battery bank with a built in BMS. Would give me 11.1V for the 817nd. I think thats quite good, I could use a step up converter to boost the voltage if necessary (or if it makes sense).


gil

They really charge up to 4.2V, then go down quickly to 4V. Don't discharge below 3V. I would trash those two bad cells...
Gil

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CroPrepper

I just put them into the ThruNite 18650 charger. Let's see if the 2 cells will revive or not.

RadioRay

This is a very good topic. D'oh!  I just remembered an old, beater laptop that may be in my junk box.  Maybe a weekend project??? (Like I ?NEED another 80% completed project... ha ha)

>Ray
"When we cannot do the good we would, we must be ready to do the good we can."  ~ Matthew Henry

CroPrepper

All 8 cells work. My charger is charging them. The question is if they can still deliver the same Wh as before, I doubt it.
Anyway, if your cell wont load because the Voltage is too low, attach it parallel to a charged cell for few seconds and then put it in the regular charger again. Saw that on yt, seems to work.

Via TapaTalk


gil

Awesome. You save a lot of money by salvaging those cells.

Gil.

CroPrepper

My cheapo bms and cellholder arrived today. The presoldered wiring is to thin, i'll have to change it.
With 4s2p I should get about 5.2Ah on roughly 14V. The initial charge is high on those, over 16V, i will need a converter.

Via TapaTalk


caulktel

I used to be in the computer business and recycled hundreds of laptop batteries and now that I know about reclaiming these 18650 cells I was only able to find one old pack which netted me 6 good cells:-(  I need to keep a eye out for some more, only now they seem hard to come by. Figures.

Joel
N6ALT

CroPrepper

As soon I ask someone for an old notebook battery they ask why. After I explain why, they won't give me a me the battery any more haha.

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CroPrepper

Finally, I am done. Ain't beautiful but it works.

3s2p 5Ah li-ion pack with bms

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Andywragg

My Job lot of 10 HP laptop batteries arrives today. Let's see how many good cells I can harvest.

BTW what BMS is that?
Once a 'STAB in the Dark'
M6UAW

CroPrepper

May 08, 2018, 04:29:11 am #11 Last Edit: May 08, 2018, 07:59:18 am by CPR
its a cheap one from banggood: https://www.banggood.com/3S-11_1V-25A-18650-Li-ion-Lithium-Battery-BMS-Protection-PCB-Board-With-Balance-Function-p-1120250.html?rmmds=myorder&cur_warehouse=CN

I am not quite sure how this reads: Over discharge voltage range: 2.3~3.0V ± 0.05V
I cant go below 3.0V with those cells, have to monitor the behavior of the BMS or if it does it automatically and how?

EDIT: i monitored a constant discharge with 600mA and noticed that one cell went far down to 2.4V and then the BMS shut off the output. When it shut off the voltage of that particular cell jumped up to 3.2V.. Why?

Andywragg

Cell voltages recover slightly when you take the load off.

Mine have arrived, not so many as I expected the ones in the advert appear to be the kind with 6-8 cells, as these packs are all 4S (rather than 3S2P or 4S2P) but they all appear to be at least 2500mAH so as long as I can get some usable ones out of them I'll be happy.

I'll take a look at that BMS.


Once a 'STAB in the Dark'
M6UAW

Andywragg

Quote from: CPR on April 13, 2018, 07:01:45 am

Anyway, if your cell wont load because the Voltage is too low, attach it parallel to a charged cell for few seconds and then put it in the regular charger again. Saw that on yt, seems to work.

Via TapaTalk


You don't really want to do this as without any load between the cells, you could end up toasting both cells. Use a resistor to throttle the in rush current.
Once a 'STAB in the Dark'
M6UAW