Trashed Tablet Lives Again Thanks To New Charger IC

Have you ever pulled a piece of electronics from the trash that looked like nothing was wrong with it, only to take it home and find out it really is dead? Since you’re reading Hackaday, we already know the answer. Trash picking is an honored hacker tradition, and we all know it’s a gamble every time you pull something from the curb. But when the Samsung Galaxy Tab S that [Everett] pulled from the e-waste bin wouldn’t take a charge, he decided to crack it open and see if it was really beyond repair.

The first step was using a USB power meter to see if the tablet was actually pulling any current when plugged in. With just 10 mA on the line, [Everett] knew the device wasn’t even attempting to charge itself. So his next step was to pull the battery and charge it from a bench supply. This got the tablet to wake up, and as far as he could tell, everything else worked as expected. It seemed like the only issue was a blown charging circuit.

Where we’re going, we don’t need ribbon cables.

Now at this point, [Everett] could have just gone online and bought a new motherboard for the tablet and called it a day. But where’s the fun in that? Instead, he wired up a simple charging circuit using a TP4056 IC on a scrap of flexible PCB and mounted it to a square of Kapton tape. He then used 34 AWG magnet wire to connect it between the tablet’s USB port and the battery, bypassing the tablet’s electronics entirely.

The fix worked, but there was a slight problem. Since the TP4056 only goes up to 4.2 V and the battery maxes out at 4.35 V, [Everett] says his hacked charger can only bring the tablet up to 92% capacity according to Android. But considering the alternative, we think its more than a worthy trade-off.

It’s easy to dismiss tablets as largely disposable devices, but this isn’t the first time we’ve seen somebody save one with little more than solder and patience. Of course, what you do with that old tablet once you get it fired back up is another story entirely.

12 thoughts on “Trashed Tablet Lives Again Thanks To New Charger IC

      1. If only that was actually a common thing…. Most devices don’t have it, and there’s no 4.1v equivalent of that TPS charger that’s in everything, at least not that I’ve ever seen.

  1. I wonder if I could save my 2012 Nexus 7 tablet. It is slow as hell with the new android releases and too old for alternative ROMs so maybe I could use it as a display by adding an HDMI in circuit or something like that.

  2. We used to use a “trick” to adjust fixed regulators that might work for the charging IC. Simply take a diode of the right forward voltage drop and put it in the ground path. The output will be boosted by that voltage drop. I think that given the low ground current, a schottky might be found to make the adjustment.

  3. The last smart device that died on me developed a puffy battery during charging that could only push in one direction due to a strong casing, so it pushed the display and PCB out to pieces. Brilliant design. Otherwise I could just have replaced the battery…

    1. Probably designed to do that, like some MacBook models that have a weak spot in their battery casing under the trackpad so when the battery puffs it cracks the trackpad to make it cost more to repair. Oh, and they have to have a real Apple battery or one that perfectly pretends to be one or it throttles the CPU to its slowest speed.

    2. Funny thing – the “flaw” of this fix will actually make it far less likely that happens.

      Time spent at 100% BSOC is really, really bad for long-term lifetime of lithium batteries.

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