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Use Galaxy S2 without a battery?

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bevo1982

Member
Oct 19, 2010
8
1
Hi There, Does anyone know if it's possible to use the Galaxy S2 without a battery, or trick it into thinking it does have one and just run off power?

My phone works, but kills a battery in about 30 minutes. There's one resistor in there that gets super hot after being water damaged, but only with a battery in.

Wouldn't know where to buy a new resistor, so wouldn't mind leaving it permanently docked and run my audio for the house through it if I can somehow run it without a battery

.
 
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Makrilli

Senior Member
Dec 12, 2011
819
170
I think it can run without battery but can't boot without battery

Sent from my sgs2 running cm9 using xda app
 

techoverload

Member
Feb 13, 2008
20
1
Sorry to revive a old thread, but I would also like to know if there is a way to trick the phone into booting from a power supply instead of a battery. I am attempting to hardwire an old S2 into an imbedded in car media player blah blah blah.....long story short I have issues using the battery.

If I leave the phone plugged into a constant powered USB when the car is off and the phone is sitting dormant it over charges, the battery gets super hot, I get the overcharge/overheat warning etc. If I disconnect it, then I have two issues, first it loses charge as it is in use and pulling it when I park means having to bring it inside and top it off etc. The second problem is....it kind of defeats the purpose of an "embedded system".

I have the software set up perfectly and I love the way it all works. My only current hitch is the battery issue. If I can bypass it I know I can run a off delay relay, so that when the car is shut off the USB cord stays "hot" for say 1 hour then shuts off thus removing power. This option seems tedious and the parts more expensive then a simple power supply replacement. Unfortunately I do not know the software side.

I have been able to get the phone to boot without a battery, however as soon as it is done booting I get the "battery low, plug in" warning, then a few seconds later the phone shuts off........Is there a way to keep the phone from shutting down at that point, or get it to ignore the fact the "battery" is at 0%?

Edit: When I say I can get it to boot without a battery, I am wiring a power supply directly to the two pins that the battery + and - would be touching.
 
Last edited:

yodaco

Member
Jan 25, 2011
18
3
Sorry to revive a old thread, but I would also like to know if there is a way to trick the phone into booting from a power supply instead of a battery. I am attempting to hardwire an old S2 into an imbedded in car media player blah blah blah.....long story short I have issues using the battery.

If I leave the phone plugged into a constant powered USB when the car is off and the phone is sitting dormant it over charges, the battery gets super hot, I get the overcharge/overheat warning etc. If I disconnect it, then I have two issues, first it loses charge as it is in use and pulling it when I park means having to bring it inside and top it off etc. The second problem is....it kind of defeats the purpose of an "embedded system".

I have the software set up perfectly and I love the way it all works. My only current hitch is the battery issue. If I can bypass it I know I can run a off delay relay, so that when the car is shut off the USB cord stays "hot" for say 1 hour then shuts off thus removing power. This option seems tedious and the parts more expensive then a simple power supply replacement. Unfortunately I do not know the software side.

I have been able to get the phone to boot without a battery, however as soon as it is done booting I get the "battery low, plug in" warning, then a few seconds later the phone shuts off........Is there a way to keep the phone from shutting down at that point, or get it to ignore the fact the "battery" is at 0%?

Edit: When I say I can get it to boot without a battery, I am wiring a power supply directly to the two pins that the battery + and - would be touching.
bump
any solutions to this yet?
 

Sparks9876

Member
Oct 12, 2013
39
5
the phone has a circuit that controls power and charge level by communicating with the battery so it will always know that the battery is removed because the battery feedback circuit will not be present.
 
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Spud2233

Member
May 3, 2014
7
2
Sorry for reviving an old thread, but i have a solution that may help others out.
I have found a way to power the Galaxy S2 GT-I9100T from an external power supply ( i have also tested on S3 GT-I9300 and S5 SM-G900I).

My first step was to create a dummy battery out of perspex, you could use any non conductive material.
Make sure you include the alignment notches and keep it as close to the size of the original battery so it is a snug fit and wont accidentally fall out.
When you know the perspex fits you can start fitting the contact terminals, make sure you have the polarity correct and that they line up with the contact terminals of the original battery and the spring terminals in the phone.
Once you have the terminals fitted you can then look at powering up your phone, i used a LM2596 based DC-DC converter that i had laying around.
If you are using a variable DC-DC converter like i did make sure you adjust the output of the power supply BEFORE connecting to your phone to prevent you destroying your device.
My DC-DC converter is set at 3.88 Volts, this value seems to trick the phone into thinking it has a battery with greater than 40% charge that way you don't get the annoying low battery alerts.

Pic.1

Pic.2

Pic.3

Pic.4

Pic.5
 
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keithross39

Senior Member
Aug 22, 2012
3,229
1,621
Oxford
How about taking your admittedly innovative idea one stage further.......
If you have an old battery laying around, why not (very carefully) remove the top part of it for use with your perspex replacement....this top section contains the overcharge protection circuit which would help to provide added protection to the device....it also has the benefits of the facts that the battery connection points are already in place and correctly aligned (it also has those alignment notches at either end).....imo, an improvement on an already good idea....
 

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szydas

New member
Feb 2, 2011
1
3
I got problem with my SGS 2 - after long on-shelf time battery drained to absoltely zero. My voltometer showed 0 on every connector. I was unable to charge or boot my phone (24h+ on charger, no signs of life). Dead, bricked, gone... Battery was relatively new (some months) so I didn't want to buy another one. Then I read Spud2233's post... and tried it .Well, kind of variation. I connected charger to phone's USB port and additional power (Motorola's dual port charger) to internal batterys connector (simly stripped old USB cable). Then battery was inserted and.... voila! After 2 or 3 retries my phone booted in and started to charge. I disconected additional power cable, phone is loading as usual. Battery revived!
Thanks for inspiration, Spud2233!
 

fpN3eqU

New member
Jul 1, 2017
4
0
I got problem with my SGS 2 - after long on-shelf time battery drained to absoltely zero. My voltometer showed 0 on every connector. I was unable to charge or boot my phone (24h+ on charger, no signs of life). Dead, bricked, gone... Battery was relatively new (some months) so I didn't want to buy another one. Then I read Spud2233's post... and tried it .Well, kind of variation. I connected charger to phone's USB port and additional power (Motorola's dual port charger) to internal batterys connector (simly stripped old USB cable). Then battery was inserted and.... voila! After 2 or 3 retries my phone booted in and started to charge. I disconected additional power cable, phone is loading as usual. Battery revived!
Thanks for inspiration, Spud2233!

Just registered to say thanks for this tip!

I too have had SII batteries go dead after too long, and the SII seems to be unable to power up without a voltage across the battery terminals. :mad:

I used a small variable power supply set to about 3.5 V. I trimmed some thin hookup wire until only a few strands were left and 'pinched' them between the battery terminals and the phone battery contacts. Then with a charger plugged in to the phone I was able to 'trick' the phone into turning on. Once booted the battery charged fine.

Note I think this should be done quickly as the phone and power supply will fight each other for as long as the voltage is placed on the contact, so I pulled the PS wires out (keeping the battery in) as soon as the phone was booted up.
 

anton_kg

Member
Apr 8, 2009
23
2
I got problem with my SGS 2 - after long on-shelf time battery drained to absoltely zero. My voltometer showed 0 on every connector. I was unable to charge or boot my phone (24h+ on charger, no signs of life). Dead, bricked, gone... Battery was relatively new (some months) so I didn't want to buy another one. Then I read Spud2233's post... and tried it .Well, kind of variation. I connected charger to phone's USB port and additional power (Motorola's dual port charger) to internal batterys connector (simly stripped old USB cable). Then battery was inserted and.... voila! After 2 or 3 retries my phone booted in and started to charge. I disconected additional power cable, phone is loading as usual. Battery revived!
Thanks for inspiration, Spud2233!

Thank you so much for the solution to my problem! I have purchased TWO batteries already and they both stopped working after drained to zero. I was blaming a charger or a quality of the battery. I found other posts suggesting to remove a capacitor but it wasn't broken...

Thanks to you, I have just booted my phone, pulled out extra power after couple minutes and it charging on its own now! (well 5% as I speak).
 

blue whale

Senior Member
Nov 26, 2010
329
18
Just registered to say thanks for this tip!

I too have had SII batteries go dead after too long, and the SII seems to be unable to power up without a voltage across the battery terminals. :mad:

I used a small variable power supply set to about 3.5 V. I trimmed some thin hookup wire until only a few strands were left and 'pinched' them between the battery terminals and the phone battery contacts. Then with a charger plugged in to the phone I was able to 'trick' the phone into turning on. Once booted the battery charged fine.

Note I think this should be done quickly as the phone and power supply will fight each other for as long as the voltage is placed on the contact, so I pulled the PS wires out (keeping the battery in) as soon as the phone was booted up.

I got problem with my SGS 2 - after long on-shelf time battery drained to absoltely zero. My voltometer showed 0 on every connector. I was unable to charge or boot my phone (24h+ on charger, no signs of life). Dead, bricked, gone... Battery was relatively new (some months) so I didn't want to buy another one. Then I read Spud2233's post... and tried it .Well, kind of variation. I connected charger to phone's USB port and additional power (Motorola's dual port charger) to internal batterys connector (simly stripped old USB cable). Then battery was inserted and.... voila! After 2 or 3 retries my phone booted in and started to charge. I disconected additional power cable, phone is loading as usual. Battery revived!
Thanks for inspiration, Spud2233!
I am in the same situation with SII batteries go dead after too long.

I do not understand this part
''I connected charger to phone's USB port and additional power (Motorola's dual port charger) to internal batterys connector (simly stripped old USB cable). Then battery was inserted and.... voila!''

or this part

'' I trimmed some thin hookup wire until only a few strands were left and 'pinched' them between the battery terminals and the phone battery contacts. Then with a charger plugged in to the phone I was able to 'trick' the phone into turning on.''

how is this different than inserting the battery in the phone and then connecting the usb power supply?
 

blue whale

Senior Member
Nov 26, 2010
329
18
so I take my dead battery, then
-take a usb charger+usb cable
-strip the usb cable to get two strands
-put one strand of the usb cable on the + of the battery
-put one strand of the usb cable on the - of the battery
=>the battery is charging
[or easier, I take battery like this,

samsung-inr18650-25r-3.jpg

put one strand of an electric cable on the +, connect this cable to the + of the phone battery, then put one strand of the electric cable on the - of the battery and the - of the phone battery

then I put the battey in the phone with usb power supply IN and the phone boots ???
 

fpN3eqU

New member
Jul 1, 2017
4
0
I wouldn't use a USB cable, 5 V is probably too high.

or easier, I take battery like this, put one strand of an electric cable on the +, connect this cable to the + of the phone battery, then put one strand of the electric cable on the - of the battery and the - of the phone battery then I put the battey in the phone with usb power supply IN and the phone boots ???

Yep, that's exactly what I did (except I used a 3.5 V power supply).

Once the phone has begun booting you should probably disconnect the "jump start" battery as quickly as possible or it'll fight the charging circuit.
 

blue whale

Senior Member
Nov 26, 2010
329
18
I wouldn't use a USB cable, 5 V is probably too high.



Yep, that's exactly what I did (except I used a 3.5 V power supply).

Once the phone has begun booting you should probably disconnect the "jump start" battery as quickly as possible or it'll fight the charging circuit.

but you agree that connecting the phone battery the charged green battery is like charging the phone battery [at least a bit]?

then I would just use the phone battery normally, by inserting it into the phone and boot the phone and finish to charge the phone battery.
 

fpN3eqU

New member
Jul 1, 2017
4
0
but you agree that connecting the phone battery the charged green battery is like charging the phone battery [at least a bit]?

then I would just use the phone battery normally, by inserting it into the phone and boot the phone and finish to charge the phone battery.

Not really, the SII battery will still be dead after a few seconds "charging". Getting the voltage across the phone battery terminals tricks the phone that there's a charged battery present so it will boot and continue charging it. Otherwise it gets stuck in something like a boot loop looking for the battery (mine did anyway).

If you could charge it separately from the phone then obviously you'd just do that. ;)
 

regsnerven

Member
Mar 16, 2016
19
4
Thank you for all your tips. I tried similar stuff, but I guess the voltage was just not right.
So I asked around to get a spare battery, which which I powered on the phone. It worked like charm.
I change the battery while the phone was running and tada! my phone was loading the "out of order" battery just fine.

Pretty much the same trick you guys did, but with less soldering and more quick magic happening ^^
 

blue whale

Senior Member
Nov 26, 2010
329
18
Thank you for all your tips. I tried similar stuff, but I guess the voltage was just not right.
So I asked around to get a spare battery, which which I powered on the phone. It worked like charm.
I change the battery while the phone was running and tada! my phone was loading the "out of order" battery just fine.

Pretty much the same trick you guys did, but with less soldering and more quick magic happening ^^

I did just that to my s2 and his dead battery.

I was scared to go with ONLY a 18650 battery to charge the dead battery (no phone or usb charger involved) : I did not know if I should connect pole+ of the 18650 with pole + of dead battery (and pole - of 18650 with pole - of dead battery) which is the parallel scheme or the opposite, to go with the ''series'' scheme
 

treysis

Senior Member
Jun 30, 2014
207
55
I was scared to go with ONLY a 18650 battery to charge the dead battery (no phone or usb charger involved) : I did not know if I should connect pole+ of the 18650 with pole + of dead battery (and pole - of 18650 with pole - of dead battery) which is the parallel scheme or the opposite, to go with the ''series'' scheme

You were right to be scared. You should not do that. The dead battery might draw too much current. That could be dangerous. Read a bit about how charging of Li-Ion batteries works: first you charge with constant current (CC), which depends on the battery's design, once it reaches the correct voltage (4.2 V for a single cell), it should go into constant voltage mode, and then you have to know at what time or remaining current you shut the charger off. A good rule of thumb is to wait till the current drops to 10% of the charging current. E.g. if you were charging the battery with 1 A***, you should turn off the charger when it's down to 100 mA.

***1 A is just an example that would work for most modern phone batteries. However, this can be different! Ideally it's written on the battery.

Also, it's very well possible that in newer phones the battery will only output voltage if the charging circuit inside the phone allows it to. At least that's the case in notebooks for many years, and I don't see why it should be very different for phones.
 
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    I got problem with my SGS 2 - after long on-shelf time battery drained to absoltely zero. My voltometer showed 0 on every connector. I was unable to charge or boot my phone (24h+ on charger, no signs of life). Dead, bricked, gone... Battery was relatively new (some months) so I didn't want to buy another one. Then I read Spud2233's post... and tried it .Well, kind of variation. I connected charger to phone's USB port and additional power (Motorola's dual port charger) to internal batterys connector (simly stripped old USB cable). Then battery was inserted and.... voila! After 2 or 3 retries my phone booted in and started to charge. I disconected additional power cable, phone is loading as usual. Battery revived!
    Thanks for inspiration, Spud2233!
    2
    Sorry for reviving an old thread, but i have a solution that may help others out.
    I have found a way to power the Galaxy S2 GT-I9100T from an external power supply ( i have also tested on S3 GT-I9300 and S5 SM-G900I).

    My first step was to create a dummy battery out of perspex, you could use any non conductive material.
    Make sure you include the alignment notches and keep it as close to the size of the original battery so it is a snug fit and wont accidentally fall out.
    When you know the perspex fits you can start fitting the contact terminals, make sure you have the polarity correct and that they line up with the contact terminals of the original battery and the spring terminals in the phone.
    Once you have the terminals fitted you can then look at powering up your phone, i used a LM2596 based DC-DC converter that i had laying around.
    If you are using a variable DC-DC converter like i did make sure you adjust the output of the power supply BEFORE connecting to your phone to prevent you destroying your device.
    My DC-DC converter is set at 3.88 Volts, this value seems to trick the phone into thinking it has a battery with greater than 40% charge that way you don't get the annoying low battery alerts.

    Pic.1

    Pic.2

    Pic.3

    Pic.4

    Pic.5
    1
    Hi There, Does anyone know if it's possible to use the Galaxy S2 without a battery, or trick it into thinking it does have one and just run off power?

    My phone works, but kills a battery in about 30 minutes. There's one resistor in there that gets super hot after being water damaged, but only with a battery in.

    Wouldn't know where to buy a new resistor, so wouldn't mind leaving it permanently docked and run my audio for the house through it if I can somehow run it without a battery

    .
    1
    the phone has a circuit that controls power and charge level by communicating with the battery so it will always know that the battery is removed because the battery feedback circuit will not be present.
    1
    I was scared to go with ONLY a 18650 battery to charge the dead battery (no phone or usb charger involved) : I did not know if I should connect pole+ of the 18650 with pole + of dead battery (and pole - of 18650 with pole - of dead battery) which is the parallel scheme or the opposite, to go with the ''series'' scheme

    You were right to be scared. You should not do that. The dead battery might draw too much current. That could be dangerous. Read a bit about how charging of Li-Ion batteries works: first you charge with constant current (CC), which depends on the battery's design, once it reaches the correct voltage (4.2 V for a single cell), it should go into constant voltage mode, and then you have to know at what time or remaining current you shut the charger off. A good rule of thumb is to wait till the current drops to 10% of the charging current. E.g. if you were charging the battery with 1 A***, you should turn off the charger when it's down to 100 mA.

    ***1 A is just an example that would work for most modern phone batteries. However, this can be different! Ideally it's written on the battery.

    Also, it's very well possible that in newer phones the battery will only output voltage if the charging circuit inside the phone allows it to. At least that's the case in notebooks for many years, and I don't see why it should be very different for phones.