What's happening with these Lithium batteries?

[McBryce]

Hi all,
      Last year a mobile phone of a friend had a strange temporary failure. The phone (a HTC One) had just been fully charged with the original charger. Shortly after (no longer connected to the charger), the phone got really hot and the charge went from 100% to zero in the space of a few minutes. Since then the phone has worked completely normal and the failure never repeated itself. Now today my iPod Nano did exactly the same thing. Right after removing it from the charger it started getting very hot, and I watched as the battery went from 100% to zero within a few minutes. I've just recharged it and it's working as normal again.
I'm no battery expert, but I assume these are failures within the battery itself, but I'd like to understand exactly what's happening and whether the batteries are safe to use after this has happened. Is this some sort of leak in the electrolyte that somehow repairs itself? Some pointers/advice from a battery chemistry expert would be welcome.

McBryce.

[james_s]

From what you've said, I suspect an internal short occurred within the battery. If that's the case then the battery is most certainly *not* safe to use but when that happens the battery will normally puff up like a balloon. An external failure is also possible, not a direct short because the battery protection would have cut out but possibly a fault or even software issue that resulted in the CPU running very hard and draining the battery.

I would suggest removing the battery and test it. Try a replacement battery if possible, unless it's an intermittent fault it should be apparent pretty quickly what the issue is.

[McBryce]

I haven't opened the iPod (I think it's still under guarantee), but we did open the HTC. The battery hadn't puffed up at all, it looked completely normal and has continued working completely normal since then (almost 18 months now). That's why I was wondering whether it somehow self repairs.

Due to the way the iPod Nano is built, I suspect the screen would pop off if the battery tried to expand at all.

McBryce.

[bitseeker]

I've had a phone and tablet do that from time to time. It takes a bit longer, more like an hour, but when I've caught it I had to reset the phone. It apparently went into an infinite loop or some such that drew a lot of current. Yours may not have been the same situation, but it sounds similar.

[james_s]

That is what it's sounding like. I've had laptop PCs get a process that starts consuming 100% CPU utilization and pretty soon the fan is screaming and the battery life is dropping fast.

[McBryce]

I have a feeling that the HTC and iPod problems are different. I just fully recharged the iPod and the battery went down 50% in the time it took to play 3 songs and was getting warm. Now I've done a hard reset and will re-test.

McBryce.

[newbrain]

I had the same happen to a new Samsung S6, 99% software fault.
No problems since then.

It also happened to my Garmin GPSMAP 64s, (on eneloops), due to a bad track: batteries drained in 20 minutes.
Pop in the reserve set, thinking I'd forgot to charge them, same thing...
Lessons learned:

• Always bring Batteroos
• Always bring a paper map (wife had one, luckily).
• Store untried tracks on the removable card.

[McBryce]

How do you mean 99% Software fault.

I haven't touched or updated the firmware. Up to now the battery lasted over 24 hours continuous play, now I just used the entire battery listening to one album!

McBryce.

[rustybronco]

Don't shrug off errant software as the cause. I've had the same issue on a couple of blackberry 10.2.X and 10.3.X installs. The battery would randomly get hot and drain in 45 minutes.

[james_s]

There is no such thing as bug-free software. Maybe it only happens once in a million tries due to a race condition or particular sequence of events but that doesn't mean it can't happen. All software contains faults and can potentially behave in unexpected ways, some more serious than others.

[McBryce]

But then the software bug had to have physically damaged the battery. Otherwise the battery life would be back to normal after a hard reset.

McBryce.

[newbrain]

How do you mean 99% Software fault.

Well, I meant in my case, and the HTC one most probably.

For the iPod, before completely ruling out a SW problem, I would try a "factory default reset" (if that's different from a "hard reset"), but it might well be a battery problem.

[janoc]

But then the software bug had to have physically damaged the battery. Otherwise the battery life would be back to normal after a hard reset.

McBryce.

Not necessarily. It could have also screwed up the stored calibration values for the battery capacity. The battery could be fine but the system thinks its capacity has dropped and is showing you false warnings about the battery being empty. A factory reset and a few charge/discharge cycles should normally clear that up.

[McBryce]

I've done a factory reset, then fully charged it. The charge lasted a whopping 42 minutes. Recharging again now.

McBryce.

[james_s]

In your earlier post you mentioned it had started working completely normal again. I would try a new battery, they are somewhat fragile.

[McBryce]

Yes, but the "working normally" didn't last long. I've now done some repeat tests: A full charge lasts betwenn 30 and 40 minutes (should be around 30 hours). It will play normally with all functions (bluetooth etc) working as normal during this time, but it also discharges in the same time even if the device is completely turned off.

Changing the battery isn't an option. The iPod is still under guarantee (I only bought it in January), so it's going back.
I suspect that the power management IC is not doing what it should and that the battery is (was) fine.

McBryce.

[bitseeker]

If it's under warranty, definitely send it back. 

[sam1275]

I don't think a software fault can drain a full battery in a few minutes, even if CPU works at 100%.
The most certain way is to test the current from the battery to the device while this happening, but since the problem happens randomly and seldom, it's not easy to do.

[McBryce]

The fact that it's inside an aluminium case with the only access being thru a glued touch screen doesn't make it any easier either

Anyway, the over excited, worryingly friendly Apple service guy tells me there's a return box on its way to me so that Apple can do the testing from here on.

McBryce.