Mediocre tablet battery

It's no secret that batteries in mobile devices usually do not last long. It is not profitable for manufacturers to make high-quality long-lived devices, so they try to the best of their abilities.
I have an old, but not bad Prestigio Multipad Visconte Quad tablet (PMP880TD), in which a standard battery failed 2 years later. The battery life has decreased to indecent 3 minutes, even if you stick a bank to it.
AIDA64 showed full battery wear

Native HX 3098120 battery at 4000mAh (3mm thick, 98mm wide, 120mm long)
I picked up the closest analogue in size to 30100120 at 5000mAh (thickness 3mm, width 100mm, length 120mm)
I didn’t even count on honest 5000mAh because I have not believed in Chinese miracles for a long time - there will be a real capacity of at least 4000mAh and thanks for that.
They sent a battery in a box for additional protection against damage.
Box



Taking it in hand, he immediately suspected something was wrong - he was too light and thin.


The caliper confirmed - lithium is clearly not therereported. The actual battery thickness was 2.3 mm, while the protection board was almost 4 mm thick due to inaccurate soldered wires. Well, why is asked to do this? He doesn’t fit into the 3mm полож

The battery naturally immediately tested charging LiitoKala Engineer Lii-260 through a makeshift adapter


Initial voltage 3.80V, internal resistance 97mOhm, real capacity after fully charged 3056mAh

A dispute was opened on the reimbursement of half the cost. The seller did not answer and the dispute was won automatically. I do not hold back the seller, I think that I acted fairly.
Torn off a piece of paper with markings just in case - under it I did not find any additional inscriptions.
Replacement
The tablet is disassembled very simply: remove the microSD card, snap off the latches around the perimeter, remove the back cover.

Remove adhesive tape from all sides

Unsolder the battery from the board. Attention! The minus wire is always soldered first, it is also soldered last. Why so? It's just much less likely to burn the board when the dangling wire tries to walk on the board
Very carefully detach the battery from the display plate, and you can not damage it, which can lead to fire.

I did not like the protection card for the new battery and I decided to rearrange it from the standard one, which has 2 keys and a thermistor.

After soldering, secured the protection board heat-resistant polyamide adhesive tape (kapton)


The new battery was glued to double-sided tape and soldered


After replacing the battery and assembling the tablet, I checked its operation in different modes before disconnecting
Brightness 50% minimum load - 4h15m
Brightness 100% video playback - 3h10m
AIDA64 showed normal battery condition

The capacity naturally seems wrong, because it does not know that the battery is not native
The new standard battery at such loads naturally worked longer.
Before throwing the old one, measured itCharacteristics: internal resistance 195mOhm, capacity 2330mAh. Normally, he did not work precisely because of the increased internal resistance. I didn’t throw it out - it’s useful for feeding something low-power.
Conclusion: although the final result cannot be called excellent, I was satisfied - the tablet is working fine and continues to please
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