Should mobile be switched off during charging?

pjran

Please could someone tell me why my mobile should be switched off while charging?

In the past I have left my phone on while it recharges BUT other half says it MUST be off. Is there a technical reason why it should be turned off?

Thanks for reading this

Pj

JAYMARSH2005

It doesnt really matter if you leave it on or off, there is a myth that you should let your battery delplete before charging it up.

pjran

JAYMARSH2005 wrote: »

It doesnt really matter if you leave it on or off, there is a myth that you should let your battery delplete before charging it up.

Thanks JAYMARSH

I'ld like to blind my husband with science :rotfl:

aliasojo

I read online (dont ask me where cos I'll never find it again) that charging a phone whilst it's on will shorten the life of the battery as it's having to 'work' whilst it's trying to charge, iyswim.

I dont know if this is right or not but I always charge mine off, whilst my son charges his whilst it's on.........my battery always lasts longer.

pjran

aliasojo wrote: »

I read online (dont ask me where cos I'll never find it again) that charging a phone whilst it's on will shorten the life of the battery as it's having to 'work' whilst it's trying to charge, iyswim.

I dont know if this is right or not but I always charge mine off, whilst my son charges his whilst it's on.........my battery always lasts longer.

My husband seems to be winning at the moment!!!!

JAYMARSH2005

aliasojo wrote: »

I read online (dont ask me where cos I'll never find it again) that charging a phone whilst it's on will shorten the life of the battery as it's having to 'work' whilst it's trying to charge, iyswim.

I dont know if this is right or not but I always charge mine off, whilst my son charges his whilst it's on.........my battery always lasts longer.

It depends on how much the phone is used,if you bought 2 handsets brand new at the same time, charged one of them when switched on and one when switched off, left them alone without using them,making calls etc then the batterys will run out at roughly the same time. Batteries usually dont hold there charge after around 6 months and will slowly start to lose there charge as they were when they were new.

I still believe your husband is losing !!

Cavey

Interesting question. Whilst I am happy with my understanding of how batteries in general work (electrochemistry and all that jazz), my understanding of rechargeable batteries is a little more limited. However, from a brief survey of the Lithium-ion (an old laptop uses this) and Li-Polymer (what my phone uses) pages on Wikipedia, they seem to be based upon a similar principle as normal batteries with the only difference being that the chemical reaction is largely reversible.

Both types (Li-ion and Li-poly) generally work on the principle that different reactions that change the oxidation state of the lithium ion occur at the anode and cathode with the lithium ions in the electrolyte being the conduction ion thereby forming a circuit (thereby giving them their name, see the wikipedia articles if you need more info).

For both types, the cell appears to degrade over time (for Li-ion ~20% per year at room temperature from the date of manufacture (whether in use or not), but ~35% at 40 degrees - keep it in your trouser pocket (body temp) and it will degrade quicker than in a handbag (room temp)). This degradation can apparently be reduced by trying to maintain the charge level at around 50% (but I would question whether this would be worthwhile, although it might explain why new batteries come at about 60% charge). These batteries must also be used within certain limits. Overcharging these batteries can result in explosion and excessively discharging them can result in an irreversible reaction that reduces the capacity of the battery. However, both of these states should be avoided by safety mechanisms built into their applications which prevent these states from being reached.

From looking at this and the page on NiMH batteries, I would guess that the "complete discharge being good for the battery" myth (?) applies to some other form of battery that is no longer used, but I can't find which. It's not lead acid either

Anyway, the recharging circuits in the phone will first off protect the cell. Secondly they will apply a reverse charge to the cell in order to reverse the reaction that creates the original voltage across the battery, thereby recharging the phone. If you remember the whole deal at school about parallel circuits, the addition of a constant voltage DC source (ie your phone "charger") can both power the phone and recharge the battery without causing any damage. Admittedly the circuit here is slightly more advanced to prevent overcharging etc..., but it still holds true the potential across the cell will rise, but it will not exceed the DC supply of the charger, such that while charging the battery, the battery is not driving the phone. The same holds for most laptops, but I have noted that the power supply is warmer when it is both charging and running than when it is just running.

So in summary (assuming my understanding for batteries plus my reading on rechargeables is accurate enough)

* the battery will degrade whether you use it or not, but if you keep it warm it goes quicker
* over-charging can cause explosions, but they build in safety circuits to stop that.
* excessive discharging causes the battery to degrade irreversibly, but there are circuits to prevent that.
* the "charger" can power both the recharge circuitry and the phone such that the battery does not drive the phone whilst charging.

Fun.

MyMateMartin

it doesn't matter at all.

If left switched on, the battery will take slightly longer to charge, that is all.

[Deleted User]

pjran wrote: »

other half says it MUST be off

Your other half is wrong-diddly-wrong-o. Now with added incorrectness!

pjran

Thank you all for your replies.

I will suggest that my husband reads all your posts and I have concluded that I can leave the phone on while charging.

Pj

Sid_Harper

Apart from your OH talking carp, also point out that some older mobiles *would not* charge if they were off! Ericson PH388 seems to ring a bell.