[Q] Running without a battery?

[Tom2112]

Has anyone tried running their Samsung Galaxy Tab 7.7 without a battery? My tab died and I think its the battery. I already replaced the tab with a Nexus 7, so I figured its time to experiment on the old 7.7 like its Frankenstein's monster.

I popped the case and pulled the old battery. I'm thinking of wiring the 30-pin connector's power + and - to where the battery plugs in. That would supply 5v from USB.

But... is 5v too much? The battery has a nominal voltage of 3.7v and can go as high as 4.2v. So I'm afraid to try it because I might fry my tab.

Also, I'm not sure what to do with the third wire on the battery. It somehow tells the tab how full the battery is but testing its voltage. I've got no idea how to fool the tab into thinking the battery is full.

Has anyone tried wiring up 5v to the battery connector? Is it safe?
Does anyone have into on how to fool the battery empty/full indicator?

Thanks in advance,
Tom

 

[Arobase40]

Why don't you simply buy a new battery available on eBay ???

 

[Tom2112]

Why don't you simply buy a new battery available on eBay ???

Sure. I could do that, but like I said, I already replaced the tab. So now I'm just experimenting, and I don't want to spend $60+ on an experiment. Plus, I'm not 100% certain that the battery is the problem.

I've got cables and wires and such lying around that I can experiment with for free. I'm thinking of building the unit into an old PC subwoofer/speaker. It would make a cool WiFi speaker/stereo. I may even wire up some old NiMH rechargeables I have lying around from my remote control car days and make the unit portable/rechargeable.

 

[Tom2112]

Well, while I had it all apart, I grabbed my meter and checked the voltage on the battery. It was 2.74v, which I guess is below the level that will allow the tablet to power on. So I decided to hook the battery up to a programmable charger that I have for remote control batteries. That charger took it from 2.74v to 4.2v

I put it back in the tablet and powered it up to find the tablet complaining that the battery was at 0%. So I booted into recovery and deleted the battery stats. After that, the tablet correctly identified the battery as being fully charged. I tested the tab for a while and it worked great, though the charge % seems to drop pretty fast. I played a silly game (2048) for about an hour or two and the battery is down to 72% already. I suspect that since I deleted the battery stats, I will need to run it all the way until it shuts down, charge it, and run it some more before the tab "gets a feel" to the battery again.

I think the battery is very suspect and I think I will continue to have problems with it.

So I am still very interested in anyone who has wired up their tab to run without the battery. What voltage did you supply it? Amps? I'm thinking 4.2v at 1.5a.

 

[MRBR7]

So I am still very interested in anyone who has wired up their tab to run without the battery. What voltage did you supply it? Amps? I'm thinking 4.2v at 1.5a.

I think what you want to do can be done..
sorry i cant help you with what to use but ive seen threads before ages ago about a guy
that wired a mobile phone into his company vehicle so he could gps track it for a few months.
The wiring had 3 wires connected to phone to fool it to think it had a full battery he said it worked no problems.
if can work with phone then it can work with tablet?....also with battery removed you could install a socket into the back to plug in the power cable...

 

[Tom2112]

Thanks MRBR7. I wish I knew what to do with that third wire!

 

[MRBR7]

http://www.makestuff.eu/wordpress/powering-a-mobile-phone-with-no-battery/
I Found that old link...
seems like you need a 82k resister on the middle one....