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Dummy Battery Problem

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brkedmrts

Member
Jan 14, 2022
5
1
First of all, i have removed the battery from the tablet and i am supplying energy from the battery terminals (in this case, i want to be able to use my charging socket for the “OTG function”)

Even though giving the constant 4.2 volt electricity with this technic, battery gauge still drains from the tablet

im using chinese branded device as tablet by the way.Device is rooted with Android 10 go edition in it.
Normally, it has 2000mAh battery and the draining speed/principle is same as the above scenario

i’m waiting for the solution ideas or any suggestions
 

V0latyle

Forum Moderator
Staff member
What exactly are you trying to accomplish?

Lithium ion batteries should NEVER be directly charged with a power source. Tablets and phones have charging controllers that regulate the charging current and voltage to avoid overcharging the battery, which at best reduces battery life, and at worst can cause catastrophic failure - including explosion and fire.
 
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brkedmrts

Member
Jan 14, 2022
5
1
What exactly are you trying to accomplish?

Lithium ion batteries should NEVER be directly charged with a power source. Tablets and phones have charging controllers that regulate the charging current and voltage to avoid overcharging the battery, which at best reduces battery life, and at worst can cause catastrophic failure - including explosion and fire.
First of all, thank you for thinking of me. I am an experienced electronic engineer and have knowledge of Li-ion batteries. For the project that I am working on, I have to not use batteries due to the variation in ambient temperature.
Since I know that a fully charged battery provides 4.2 volts of energy, i remove the battery and so, supply this voltage from the place where the battery should normally be inserted.
When I turn on the tablet, the battery percentage shows 100%, after 20 minutes it drops to 85% approximately.

I don’t give the direct energy to the battery btw, on the contrary, i’m giving the energy from another source that the battery should normally give.

The attached photo can help you to have an idea for the situation

I just need to prevent the system for lowering the battery level as if like there is still battery in the tablet
 

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V0latyle

Forum Moderator
Staff member
First of all, thank you for thinking of me. I am an experienced electronic engineer and have knowledge of Li-ion batteries. For the project that I am working on, I have to not use batteries due to the variation in ambient temperature.
Since I know that a fully charged battery provides 4.2 volts of energy, i remove the battery and so, supply this voltage from the place where the battery should normally be inserted.
When I turn on the tablet, the battery percentage shows 100%, after 20 minutes it drops to 85% approximately.

I don’t give the direct energy to the battery btw, on the contrary, i’m giving the energy from another source that the battery should normally give.

The attached photo can help you to have an idea for the situation

I just need to prevent the system for lowering the battery level as if like there is still battery in the tablet
Oh okay, I suspected that's what you were doing, I was just trying to make sure in the interest of safety and all that. It's all fun and games until someone gets hurt...

It's really hard to say why the battery gauge reports 85% even though you're supplying 4.2 volts of power. Depending on the firmware, Android battery gauges aren't simple voltmeters that simply display a percentage based on a certain voltage curve. They're a bit more advanced than that, and factor in the load on the battery too.

Here is a better explanation on how the systems work.
 
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brkedmrts

Member
Jan 14, 2022
5
1
I would like to add another question that makes me wonder, will the battery percentage stay constant somewhere and/or will it start to rise after some point?

If there is no way to prevent the battery from decreasing in terms of software, I don't want the screen to go black when it reaches 15% and turn off at 0%. I'm going to make a supercapacitor and a modification to charge.

Or if I arrange the android as if there is a battery near infinity, I think that I can almost stop the battery percentage decrease rate, is that logic possible?
 
Last edited:

V0latyle

Forum Moderator
Staff member
I would like to add another question that makes me wonder, will the battery percentage stay constant somewhere and/or will it start to rise after some point?
I honestly don't know.
If there is no way to prevent the battery from decreasing in terms of software, I don't want the screen to go black when it reaches 15% and turn off at 0%. I'm going to make a supercapacitor and a modification to charge.

Or if I arrange the android as if there is a battery near infinity, I think that I can almost stop the battery percentage decrease rate, is that logic possible?
If you're powering the device via a constant DC supply that doesn't drop voltage under load, I would imagine the battery indicator would eventually stop at some point and just remain at a certain percentage. Again, this depends on what sort of controller the device has; if it's an adaptive learning battery management system, it might be ignoring the supply voltage, and is calculating how much power the device has used so far. Eventually it'll figure out that the voltage isn't dropping as expected, but I have absolutely no idea what it'll do.

I'd say just leave it playing video or something for a while and see what happens.
 
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brkedmrts

Member
Jan 14, 2022
5
1
I honestly don't know.

If you're powering the device via a constant DC supply that doesn't drop voltage under load, I would imagine the battery indicator would eventually stop at some point and just remain at a certain percentage. Again, this depends on what sort of controller the device has; if it's an adaptive learning battery management system, it might be ignoring the supply voltage, and is calculating how much power the device has used so far. Eventually it'll figure out that the voltage isn't dropping as expected, but I have absolutely no idea what it'll do.

I'd say just leave it playing video or something for a while and see what happens.
I had decided to try my super capacitor idea. However, For a device whose charge level drops while charging with its original battery installed, this was not very wise.

but I added a capacitor as shown in the attached image and I've been testing it for 25 minutes.

battery percentage 99% for last 20 minutes.I t hope I managed to manipulate it somehow.

I will be sharing the results,Also, thank you for your interest.
 

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  • 1
    What exactly are you trying to accomplish?

    Lithium ion batteries should NEVER be directly charged with a power source. Tablets and phones have charging controllers that regulate the charging current and voltage to avoid overcharging the battery, which at best reduces battery life, and at worst can cause catastrophic failure - including explosion and fire.
    1
    First of all, thank you for thinking of me. I am an experienced electronic engineer and have knowledge of Li-ion batteries. For the project that I am working on, I have to not use batteries due to the variation in ambient temperature.
    Since I know that a fully charged battery provides 4.2 volts of energy, i remove the battery and so, supply this voltage from the place where the battery should normally be inserted.
    When I turn on the tablet, the battery percentage shows 100%, after 20 minutes it drops to 85% approximately.

    I don’t give the direct energy to the battery btw, on the contrary, i’m giving the energy from another source that the battery should normally give.

    The attached photo can help you to have an idea for the situation

    I just need to prevent the system for lowering the battery level as if like there is still battery in the tablet
    Oh okay, I suspected that's what you were doing, I was just trying to make sure in the interest of safety and all that. It's all fun and games until someone gets hurt...

    It's really hard to say why the battery gauge reports 85% even though you're supplying 4.2 volts of power. Depending on the firmware, Android battery gauges aren't simple voltmeters that simply display a percentage based on a certain voltage curve. They're a bit more advanced than that, and factor in the load on the battery too.

    Here is a better explanation on how the systems work.
    1
    I would like to add another question that makes me wonder, will the battery percentage stay constant somewhere and/or will it start to rise after some point?
    I honestly don't know.
    If there is no way to prevent the battery from decreasing in terms of software, I don't want the screen to go black when it reaches 15% and turn off at 0%. I'm going to make a supercapacitor and a modification to charge.

    Or if I arrange the android as if there is a battery near infinity, I think that I can almost stop the battery percentage decrease rate, is that logic possible?
    If you're powering the device via a constant DC supply that doesn't drop voltage under load, I would imagine the battery indicator would eventually stop at some point and just remain at a certain percentage. Again, this depends on what sort of controller the device has; if it's an adaptive learning battery management system, it might be ignoring the supply voltage, and is calculating how much power the device has used so far. Eventually it'll figure out that the voltage isn't dropping as expected, but I have absolutely no idea what it'll do.

    I'd say just leave it playing video or something for a while and see what happens.
    1
    I honestly don't know.

    If you're powering the device via a constant DC supply that doesn't drop voltage under load, I would imagine the battery indicator would eventually stop at some point and just remain at a certain percentage. Again, this depends on what sort of controller the device has; if it's an adaptive learning battery management system, it might be ignoring the supply voltage, and is calculating how much power the device has used so far. Eventually it'll figure out that the voltage isn't dropping as expected, but I have absolutely no idea what it'll do.

    I'd say just leave it playing video or something for a while and see what happens.
    I had decided to try my super capacitor idea. However, For a device whose charge level drops while charging with its original battery installed, this was not very wise.

    but I added a capacitor as shown in the attached image and I've been testing it for 25 minutes.

    battery percentage 99% for last 20 minutes.I t hope I managed to manipulate it somehow.

    I will be sharing the results,Also, thank you for your interest.