Why does the battery level going down, when there is no battery installed?

Hi,

I have a 7" tablet, which battery got a damage, and stopped working. I replaced the battery with an USB cable, and plug it into a 850maH phone charger.

First of all, the tablet keep saying that there is an over voltage in the battery. I assume its because I have 5V instead of 3.7V. I don't know if i could cause some problems in the future or not.
Second: if I connect some other mobile charger like a bigger one, the screen stops responding, or goes crazy. I experienced something like this when charging an old phone. Possible causes?
Third: the most interesting thing is, that my tablet says its battery is draining. It is mostly constant, faster when screen is on, even though there is no battery in it...

If you guys have an answer to any of these questions, I would really appreciate your help.

Thank you in advance,
Leslie Spike

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808PUNABOY24 days ago

Probably because the capacitors have not dissipated ( fully drained ) yet,.....

it also sounds like your battery may be punctured. Due to over voltage capacity charging.

-max-27 days ago
I have a 7" tablet, which battery got a damage, and stopped working. I replaced the battery with an USB cable, and plug it into a 850maH phone charger.

First of all, the tablet keep saying that there is an over voltage in the battery. I assume its because I have 5V instead of 3.7V. I don't know if i could cause some problems in the future or not.

You should be thankful you did not completely destroy your tablet!!! Replacing the battery with a direct power supply is a very bad idea unless you know what you are doing. It IS definitely overvoltage, because lithium batteries should never exceed 4.20 volts. Your power supply is attempting to deliver 5.0 volts directly where the battery was, and your tablet does not never intended for that to happen. You may have fried the battery charging circuitry, I am surprised you did not release the magic smoke entirely, from either the tablet or the wall charger.

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Second: if I connect some other mobile charger like a bigger one, the screen stops responding, or goes crazy. I experienced something like this when charging an old phone. Possible causes?

It's probably a sign that you are damaging components, or pushing them beyond their absolute maximum ratings. Given that the supply was not designed to power the device, it may be that the 'charger' is going into some overcurrent protection mode, causing a fluctuating, inconsistent power output. The glitchy power is messing with the critical electronics inside your tablet, constantly resetting the state of certain ICs.

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I don't know how the tablet has implemented SoC (State of Charge) measurements. Lithium batteries typically have additional connectors, with a digital interface allowing a chip internal to the battery to do bookkeeping on the charge entering and leaving the cell, and reporting a SoC figure to your device upon request. Or if it's poorly implemented, it may just be measuring the fluctuating voltage of the power supply

You can't just replace a 3.7V battery with a 5V charger.
Not only is the voltage too high but with the missing battery nothing in your tablet works as it should.
And if you installed your new USB directly where the battery was instaed of using the USB port it won't keep working for long.
You ask a lot of questions but answered them yourself by ripping the battery out ;)

+1

OP never learned of self-discharge.

Hmmm, see I always learn new things here!
For some weird reason I was under the impression that a device without a battery won't suffer from self discharge ;)

iceng27 days ago

This is tech-no babble !^e

Increasing the voltage of internal supply is tantamount to a slot gamer sparking the one armed machine in hopes of Forcing a Jackpot..

The delicate tablet electronics cannot be expected to survive a 35% increase in supply Voltage without incurring serious and permanent damage !!!!!!!!