Charging times and ageing batteries

[HareBrain]

Rechargeable batteries take longer to charge as they get older. Does this mean they take more electricity to charge, or are they just taking electricity from the mains at a slower rate? Or (most likely, in my experience) a third option I haven't considered, will take two pages to explain and which I won't understand?

 

[Pyan]

I find that more and more things these days are covered by your third option...

 

[CupofJoe]

From my VERY LIMITED understanding it is something like the first option.
Or more exactly, whatever the battery is made of is with use getting thicker/opaque to the charge and it is harder for the charge to get stored.

 

[Christine Wheelwright]

I think it is closer to the second option. The ageing increases the impedance of the cell and therefore current flows at a reduced rate during charging. Therefore the time taken to charge is longer (as energy is volts x amps integrated over the time period of the charging). There will also be a loss in efficiency leading to slightly higher cell temperature during charging and meaning the difference between the energy in and the energy out gets wider.

 

[HareBrain]

more things these days are covered by your third option

it is something like the first option

I think it is closer to the second option

Brilliant.

 

[Christine Wheelwright]

Option 1 and 2 are not mutually exclusive. The increased cell impedance reduces the charging current. It also increases the heat energy produced within the cell during both charge and discharge (reducing cell efficiency). So, yes, more energy is needed to charge the cell and the charge duration (per unit of charge) is increased.

 

[Wayne Mack]

I would lean to the second option as battery chargers consume power even without a battery attached. Also, given that the battery emits heat as it charges, the battery itself is wasting energy during the charge time. I suspect, though, leaving the charger plugged in while it is not in use is far more wasteful.

 

[Dave]

leaving the charger plugged in while it is not in use is far more wasteful.

It's also dangerous, and as I know anecdotally of a couple of house fires as a result, I'm now very careful not to do this anymore. (We also don't put on the Dishwasher or Tumble Drier when we are out of the house for the same reason.)

 

[Ursa major]

Brilliant.

If your battery is getting so hot that it's emitting a brilliant light, you may have a bigger problem than an increase in your electricity bill.


Just sayin'.

 

[Wayne Mack]

If your battery is getting so hot that it's emitting a brilliant light, you may have a bigger problem than an increase in your electricity bill.


Just sayin'.

Does this mean that you will be delighted if you get a new battery?

 

[tinkerdan]

One question that might be asked--because around here I have to keep checking behind someone--are you using the correct charger for that battery? with so many different devices and some different charging voltage requirements, it is easy to find someone using the wrong charger for a device and having problems with charging the device.

 

[HareBrain]

are you using the correct charger for that battery?

Yes, always. And I've noticed the same thing across all devices.

 

[tinkerdan]

Back when rechargeables were simple:
I recall that the biggest problem was that each time they were charged they could lose capacity until they charged quickly and dissipated quickly.
When I managed a McDonalds the drive-thru gear was run by such and that was the biggest headache when the battery seemed to charge very quickly and then worked for about ten or 15 minutes and gave out.

These days the batteries use all sorts of digital charging that can vary based on the chemistry of the batteries. This is often regulated at the battery with a circuit board that regulates the chargers voltage. I've no doubt that some might even have programic ways of regulating the charging--often making updates suspect when charge times change.

a quick guess is that something is choking the current and slowing down the charging of the battery--this might be good in the sense that many of the latest batteries need to slow charge anyway--the slower the current flow the less power used.

However: checking to see how hot the charger is might warn you that something else is wrong and that you might be risking fire--Maybe some sort of voltage drop going on. Are you directly connected to an outlet or connected through a power bar with a cord longer than three feet?