After about seven hours with very little useage, my Asus Smartphone has gone from 75% right down to 4%.

 

The wifi is turned off, the phone is about 5 years old and was not used for about the last three years, I am only going to

use it for listening to music or watching movies while flying or on long journeys.

 

Any idea which could be causing the battery to drain so quickly?

Try a new battery.

Had this happen with a cheapo Leagoo this month - first time from 100% to turn off in less than 3 hours and no usage.  Also on power saver mode with no wifi or anything.  Then it worked normally for several days before doing it again.  Phone only one year old so probably should not be the battery but indeed seems likely - either that or software running phone amiss.  

 

Rather than change battery bought a Redmi 5A for 2880 baht and this runs a week with more than 50% charge remaining.  And if I ever want smart phone options has the ability to run them (unlike the previous 1,500 baht phone without enough memory to even update apps).  

If you have Data turned on and / or Bluetooth that will drain the battery quickly

19 minutes ago, possum1931 said:

the phone is about 5 years old

Does it have a Lithium/Ion battery?

 

Unfortunately the much appraised Lithium/Ion batteries have a quite limited lifetime.

Independent of usage.

 

21 minutes ago, possum1931 said:

was not used for about the last three years

This can be a killer if the battery was empty(?) for three years.

Li/Ion batteries are best stored with 50% charge.

1 minute ago, upu2 said:

If you have Data turned on and / or Bluetooth that will drain the battery quickly

Very true.

Mobile data on is one of the biggest drains.

 

But from the OP it does not sound like this is the problem here?

1 minute ago, KhunBENQ said:

Very true.

Mobile data on is one of the biggest drains.

 

But from the OP it does not sound like this is the problem here?

It doesnt I agree but if as you say in your post the battery is 5 years old then that is the most likely candidate for the problem. As you know batteries have a life expectancy of maybe 3 years quite often less. As the age the storage capacity diminishes and as a result so doe the life of the battery. I think you are spot on with the battery being the problem

51 minutes ago, upu2 said:

If you have Data turned on and / or Bluetooth that will drain the battery quickly

Data, wifi, bluetooth not on.

52 minutes ago, KhunBENQ said:

Does it have a Lithium/Ion battery?

 

Unfortunately the much appraised Lithium/Ion batteries have a quite limited lifetime.

Independent of usage.

 

This can be a killer if the battery was empty(?) for three years.

Li/Ion batteries are best stored with 50% charge.

Maybe that's the problem.

1 hour ago, KhunBENQ said:

Does it have a Lithium/Ion battery?

 

Unfortunately the much appraised Lithium/Ion batteries have a quite limited lifetime.

Independent of usage.

 

This can be a killer if the battery was empty(?) for three years.

Li/Ion batteries are best stored with 50% charge.

i don't really know what kind of battery it is.

 

Is it time to upgrade your phone with a new phone purchase?

 

https://www.howtogeek.com/244748/how-to-see-which-apps-are-draining-your-battery-on-an-android-phone-or-tablet/

17 hours ago, johng said:

Try a new battery.

yes the battery is finished get a new battery, i always find the battery the phones comes with is the best battery you will ever get the new batteries you buy even if from the makers and not copies they are never as good.

I have a phone 4 yrs old my battery shows 82 % of whennew what I Do is never charge to 100 per cent never leave on charge overnight usually charge to like 85 per cent and phone good all day try turning your battery to low use 

Batteries lose their ability to recharge if left discharged for a long time, especially Lithium-Ion type. Try to find a new battery. Other option would be to try jump starting it, but that may be dangerous.

You were lucky to get anything after such a long time off and a 5 year old battery.

Even if it's removal, finding a battery will be difficult for such an old model.

Time to get a new device !

19 hours ago, possum1931 said:

the phone is about 5 years old and was not used for about the last three years

Your battery is probably toast. When replacing don't throw the old one in the garbage but give it to the store for proper disposal (ask what they do with it first because they might just though it in the garbage). Lithium is extremely toxic to health and bad for the environment.  

31 minutes ago, RBOP said:

Your battery is probably toast. When replacing don't throw the old one in the garbage but give it to the store for proper disposal (ask what they do with it first because they might just though it in the garbage). Lithium is extremely toxic to health and bad for the environment.  

Actually, I think I may have found the problems, little things here and there from you nice posters, things like

the brightness up at full. Also a very helpful link. Thanks everybody.

The battery has some self discharge which will be noticeable if left unattended for three years. Also simply turning off the 'phone does not disconnect the battery. There will be a continuous drain on it which is negligible for a few weeks but will add to the self discharge and, during the three years of non-use will most likely reduce the battery voltage close to if not below the rechargeable level. As has been said, get a new battery.

22 hours ago, possum1931 said:

Data, wifi, bluetooth not on.

Get your battery changed. They dont last forever and if you have had the phone a few years as I believe you have then the battery is the most likely problem. Also, allow your phone to totally drain the power before you charge it. Charging a partially full battery will reduce the life of it

11 minutes ago, upu2 said:

. Charging a partially full battery will reduce the life of it

Sorry but not true.  Think of your car.  

17 minutes ago, lopburi3 said:

Sorry but not true.  Think of your car.  

It is actually very true. Car batteries and phone batteries are different

8 minutes ago, lopburi3 said:

Sorry but not true.  Think of your car.  

Absolutely right Lopburi. The true measure of a battery is the number of charge/discharge cycles you can get from it. The deeper it is discharged, the fewer are the number of cycles. From that it follows that if you recharge your battery when it gets to 70% you should get something like 2,000 cycles from it. Conversely if you wait until the charge indicator shows red every time then the number of cycles is likely to be in the region of 300.

The car battery (lead acid) must be kept fully charged to maintain a decent life expectancy so it behaves differently from Lithium but the point was well made.

1 hour ago, upu2 said:

Get your battery changed. They dont last forever and if you have had the phone a few years as I believe you have then the battery is the most likely problem. Also, allow your phone to totally drain the power before you charge it. Charging a partially full battery will reduce the life of it

Good advice, though I have just found out my battery is fine now thanks to some nice posters. Thanks again.

1 minute ago, possum1931 said:

Good advice, though I have just found out my battery is fine now thanks to some nice posters. Thanks again.

You are very welcome

I had the same problem with an HTC One every now and then. The reason was an app which kept restarting over and over in the background. I then installed a cleaner app and ran it after every usage and the problem was gone.

 

As others have already pointed out, batteries have a shelf life. A 5 year old battery probably has only 75% of its original capacity, if it’s a comparatively small battery to begin with, then it will rund out of juice fairly quickly.

59 minutes ago, upu2 said:

It is actually very true. Car batteries and phone batteries are different

I am well aware of that - you might want to read this as it is very important to maintain Li-ion batteries within a normal charged range.

https://www.scienceabc.com/innovation/does-letting-a-phone-discharge-completely-before-charging-it-again-improve-its-battery-life.html

 

5 hours ago, RBOP said:

Lithium is extremely toxic to health and bad for the environment.  

Actually Li-ion batteries are much less toxic than other types. 

Quote

Environmental concerns and recycling
Since Li-ion batteries contain less of toxic metals than other types of batteries which may contain lead or cadmium[89] they are generally categorized as non-hazardous waste. Li-ion battery elements including iron, copper, nickel and cobalt are considered safe for incinerators and landfills.

https://en.wikipedia.org/wiki/Lithium-ion_battery

On 7/29/2018 at 2:11 PM, possum1931 said:

The wifi is turned off, the phone is about 5 years old and was not used for about the last three years

There's your answer. I took my iPhone 6 battery in for testing at just over 3 years old, and they replaced it under their special exchange program. These batteries don't last all that long even if you use them every day. Not using them at all kills batteries quickly.

On ‎7‎/‎29‎/‎2018 at 6:26 PM, possum1931 said:

Data, wifi, bluetooth not on.

Something you could try

Drain the battery below 10% then recharge to 100% without interruptions

worth a try, it worked with my iPhone only 2 years old