[blzr409]

I have a 1520.3 running the 10 preview. The phone is about a year and a half old. I haven't had any major issues until the last couple weeks. It started when I was playing games on the way home from work (public transportation), the phone would randomly pop up with the "Battery Critically Low" message and then shut off instantly. i could have a 90% charge and it would still happen. A lot of the time I would be able to turn it right back on and still have a good amount of battery left. I assumed it was game related.

A couple weeks have gone by and it's now started happening more frequently and seems to be completely at random. I did a hard reset a few days ago and it doesn't seem to have changed anything. This morning I had a full charge, used it for a bit, then was playing music in my car. I had checked a few minutes before and the battery was at 88%. Suddenly the "battery critically low" thing happened and the phone shut off. I turned it back on and it's now at 75% and working fine.

There have been other times this has happened in a similar situation and when I turn it back on the battery will be extremely low (like 3-10%), then I can reset it and it will suddenly say 50%. I can't make any sense of any of it. Any ideas?

[Steve Thackery]

It's quite likely that the battery is failing. There is one important fact that often gets overlooked: the battery percentage figure is only meaningful when the battery is in good condition.

When a battery begins to fail its internal resistance increases. This causes an unexpectedly high voltage drop when the phone is drawing a lot of current - such as when playing certain games. The reduced voltage from the battery makes the phone think the battery is almost flat, hence the "Critically Low" message. As soon as the high current draw goes away (i.e. when the phone has been restarted and the game isn't running) the battery voltage recovers and the phone reports a good amount of charge again.

I was a electronics bench technician some years ago, and symptoms like this are very common with failing batteries.

The main thing to remember is that the percentage charge figure is not reliable if the battery is failing, so don't be fooled by it.

Depending upon how handy you are, you could replace the battery yourself, or have a repair shop do it.

But wait for some other replies to come in first. The current fashion is for people to blame W10 for it, so if you've got W10 on your phone you'll be getting lots of advice about how rubbish it is. In the end, though, I think you'll come to the conclusion that you really do just need a new battery fitting.

[blzr409]

I am running the 10 preview, but it actually started on 8.1, so I think you're probably right. Thanks for the info! I think I've found batteries on eBay and and watching the videos online I think I should be able to do it myself. I do have a backup phone just in case.

[POLAT ALEMDAR]

This issue happened with me after updating to WP10 and back to 8.1 and still :(
I dont have enough money to replace battery or fix it
but i see alot of people here face this issue
we should contact Microsoft

[JPDVM2014]

It is definitely your battery failing. The same thing happened to mine. Thankfully, replacing the battery is pretty straightforward.

[dbrie]

I recommend replacing the battery with a genuine Nokia battery - I just did it last night and has made all the difference. Give yourself about an hour to complete the whole disassembly and replacement process - that's about how long it took me but it was worth it!

[hyedefinition]

I recommend replacing the battery with a genuine Nokia battery - I just did it last night and has made all the difference. Give yourself about an hour to complete the whole disassembly and replacement process - that's about how long it took me but it was worth it!

Where were you able to find a genuine battery? I'm seeing a lot of non-OEM batteries out there.