Change/modify battery for tablet

Hi everybody! I have a question that maybe I already know the answer but I'm going to ask you just to make sure...
I own a tablet with an almost dead battery... That battery can be removed and it's connected through a cable to the slot.... I also have some li-ion battery called 18650 (3.7v working voltage and 4.2v when fully charged) , the question is... If I cut the wired from the old battery and I connect them to the 18650 the tablet should work and charge like with old battery isn't it?

Thanks in advance

I shall quote @"phyrrus9".

He's well and truly capable of answering this.

(11-03-2020, 06:33 PM)ratto1334 Wrote:

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Hi everybody! I have a question that maybe I already know the answer but I'm going to ask you just to make sure...
I own a tablet with an almost dead battery... That battery can be removed and it's connected through a cable to the slot.... I also have some li-ion battery called 18650 (3.7v working voltage and 4.2v when fully charged) , the question is... If I cut the wired from the old battery and I connect them to the 18650 the tablet should work and charge like with old battery isn't it?

Thanks in advance

Absolutely not. Not all lithium ion batteries are created equal, and not all 18650 batteries are even the same chemistry. Discharge and inrush currents that are stable on some chemistries are deadly (explosion) on others. Charging is much the same, the charger built into the device was designed for a specific non-replaceable battery. Because of that fat, the manufacturer very likely put no logic or protection in for the event that a different type or value cell was put in its place.

That's not to say you couldn't make the swap, but if you do, you're likely at risk of either killing the device or yourself.

Thanks for the answer! So as I got even if they have same voltage and same milliampere (500 in discharge and 500 in charge) it's not safe..
Would be better maybe to connect directly to a power supply or can be worst...?
Thanks in advance

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Or maybe there are some things I need to check before trying this li-ion battery with same voltage and same milliampere? Like some specifis to make sure it's ok?
Only things I know at the moment it's voltage when operating, mliampere of charge/discharge, and voltage at full charge..

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There are some specifics I could check to make sure it's safer or not? I just know at the moment operating voltage 3.7 (typical voltage of smartphone and tablet) , the voltage of the battery when fully charged 4.2v (usually all the li-ion are like that) , and milliampere 500 per hour in charge

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Even in both battery the old and the new there is written 3.7v and they are both 4.2v when full charge

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Charging the battery only with the specific charger could help?

(11-04-2020, 02:47 PM)ratto1334 Wrote:

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Thanks for the answer! So as I got even if they have same voltage and same milliampere (500 in discharge and 500 in charge) it's not safe..
Would be better maybe to connect directly to a power supply or can be worst...?
Thanks in advance

---

Or maybe there are some things I need to check before trying this li-ion battery with same voltage and same milliampere? Like some specifis to make sure it's ok?
Only things I know at the moment it's voltage when operating, mliampere of charge/discharge, and voltage at full charge..

---

There are some specifics I could check to make sure it's safer or not? I just know at the moment operating voltage 3.7 (typical voltage of smartphone and tablet) , the voltage of the battery when fully charged 4.2v (usually all the li-ion are like that) , and milliampere 500 per hour in charge

---

Even in both battery the old and the new there is written 3.7v and they are both 4.2v when full charge

---

Charging the battery only with the specific charger could help?

The voltage is only a measure of its cell count, and the discharge and charge rates are NOT the same. Those are only maximums also. Lithium-cobalt, lithium-phosphate, lithium magnesium, etc all have completely different operating parameters, while some cells may have identical ratings. You can google how charge cycles in Lithium chemistry batteries work, and you'll soon notice that they need specialized equipment to charge. To replace the battery you will need to find a cell that is identical within the parameters that the charging circuitry and power bus was designed for. Realistically this means you'll need to find a battery that is identical to the one coming out. It's probably cheaper to buy an exact replacement than to find an alternative.

Thanks again...
Do you think that if I charge the batteries with the specific charger would be safer? (I have it) Cause I have 6 battery 18650, they all comes from an old laptop and I used them for many pourposes and till now everything ok... It's not a powerful tablet... It's dual core and 7 inch screen and the consume should be low.. considering that with a 1600mhampere battery can work for about 3 hours watching a movie