• New Patreon Tier and Early Access Content available. If you would like to support AVForums, we now have a new Patreon Tier which gives you access to selected news, reviews and articles before they are available to the public. Read more.

Question Trick a tablet into thinking that it has a battery?

PerfectBlue97

Active Member
I have an android powered tablet(ish) device with a special kind of stand/mount that is incredibly useful, due to the unique mounting arrangements.

The battery recently died (swelled up to dangerous proportions) and I'm having difficulty finding a replacement. I removed the battery in the hope that it would run on mains power alone, but it's totally dead.

Is there any way to trick it into thinking that it still has a battery installed?

It's one of the 3 wire type batteries that's soldered in place.

The tablet and battery are both long discontinued and obscure (Chinese made, no English language), and I'm currently looking for replacements for both, but in the interim I'd like to at least be able to run the tablet on mains power.

If I can't get a replacement for the tablet\battery I'll start another thread looking for alternatives and end this thread, but right now I'm only really interested in some electrical advice. Actual soldering and things won't be a problem, I can follow instructions but I'm not familiar with the ins and outs of tablets and their batter\charging\fail-safe arrangements.
 

PerfectBlue97

Active Member
Worth asking...have you checked the mains power unit is actually outputting anything?

Yes, it's just a standard USB plug.

The battery is in really bad shape, and it stopped running when I took it out.
 

EndlessWaves

Distinguished Member
I've never tried it but I guess you could replace the cells with different ones, especially if you were willing to mount them outside the case or accept less battery life do you didn't need an identical size.

I know it used to be done for laptops when they were still using standard sized cells. Most tablets I've come across use normal 3.7v lithium batteries.

With three connectors I guess you removed an entire battery pack including the protection pcb?
 

PerfectBlue97

Active Member
I've never tried it but I guess you could replace the cells with different ones, especially if you were willing to mount them outside the case or accept less battery life do you didn't need an identical size.

I know it used to be done for laptops when they were still using standard sized cells. Most tablets I've come across use normal 3.7v lithium batteries.

With three connectors I guess you removed an entire battery pack including the protection pcb?

Right now, I simply can't find a compatible battery as it's an older model battery from a heavily bespoke tablet device and the original manufacturer no longer makes it and hasn't done so for quite a while. If I can find one then it's hopefully simply going to be a matter of soldering the wires in place.

If I find a battery then that's great, but I'm currently looking to run the tablet off of mains power, so I need to trick it into thinking that the batter is still connected.

The battery had a PCB connected to it with three wires, when I cut the wires the PCB was left on the battery part as it was integrated into the battery. I still have it in my possession.
 

bernado

Well-known Member
I'm really sorry I don't have a solution but I would be very worried about bodging something in the power circuit.
It sounds like it's had a good innings and what you're trying to achieve is potentially dangerous, even if it is intended a temporary solution.
 

PerfectBlue97

Active Member
I'm really sorry I don't have a solution but I would be very worried about bodging something in the power circuit.
It sounds like it's had a good innings and what you're trying to achieve is potentially dangerous, even if it is intended a temporary solution.

The tablet can already accept mains power, so I'll be using the same mains regulating circuits as normal. It shouldn't be any more dangerous than running while charging.
 

bernado

Well-known Member
The tablet can already accept mains power, so I'll be using the same mains regulating circuits as normal. It shouldn't be any more dangerous than running while charging.
I get it is designed to take external power but once you start removing bits in that area it's no longer as designed.
Good luck but after seeing a house fire resulting from a similar exploit it's not something I would consider.
 

PerfectBlue97

Active Member
I get it is designed to take external power but once you start removing bits in that area it's no longer as designed.
Good luck but after seeing a house fire resulting from a similar exploit it's not something I would consider.

Well, why don't you tell me what they did wrong, and I'll be sure to put in whatever precaution they didn't.

I'm looking to do this properly, not just to bodge it. Batteries typically come with build in safety features (Hence the third wire which is usually connected to one or more sensors), I still have the battery and the board. So I can reconnect them as required. Possibly with a different battery, or some kind of capacitor to replicate the presence of the battery.

This is a specialist device that I use on a daily basis, I'm looking for a replacement device, and a replacement battery, but I need a stop gap. A conventional tablet with added software\hardware isn't cutting the mustard for me right now.
 

PerfectBlue97

Active Member
That my friend is something we'll never know

I'm rather curious to know what would be in a tablet that could combust at such a low voltage, but which wouldn't also trip the breakers out, tablets don't usually have the kind of components that would burn fiercely enough. Ironical, it's often the batteries that do this.

Normally when an electrical device overloads and causes a fire it's the charger unit that overheats and melts at mains voltage, not the device attached to it.

Are you sure that it wasn't just a fake Chinese charger that did it, or a bad battery?

I'm looking at taking the battery out, but keeping the safety circuits, so in principal it should be just as safe as if it goes over voltage or over heats the protective circuits will still be in place and will cut out exactly as if there was a battery there. If the whole thing shorts out, well, that's what an RCD is for.
 

The latest video from AVForums

Fidelity in Motion's David Mackenzie talks about his work on disc encoding & the future of Blu-ray
Subscribe to our YouTube channel

Full fat HDMI teeshirts

Support AVForums with Patreon

Top Bottom