Rechargeable NiMH 1.2v batteries

[Stilllearning]

Mrs S uses the above batteries in the wireless mouse for her laptop. When her screen tells her that the batteries (two of them) have 52%  battery level, what exactly does this mean, and does it take into account the age of the battery, if it can still give out all the theoretically available power, etc. They do tend to go flat quicker than she likes or considers reasonable.

[WotEver]

It’s almost certainly 52% of usable capacity remaining. She can take it down to flat and then recharge if she’d like. 

[peterboat]

I have those batteries in my Honda Insight!

[Chewbacka]

2 hours ago, Stilllearning said:

Mrs S uses the above batteries in the wireless mouse for her laptop. When her screen tells her that the batteries (two of them) have 52%  battery level, what exactly does this mean, and does it take into account the age of the battery, if it can still give out all the theoretically available power, etc. They do tend to go flat quicker than she likes or considers reasonable.

The mouse probably just measures voltage and using the voltage/power graph for alkaline batteries estimates the power remaining, at least that’s how my old gps handheld worked.  But as NiMH batteries naturally have a lower voltage than alkaline they appear to be a bit flat, so probably underestimates the power remaining, so just keep using them until it stops working and then recharge.

[nicknorman]

2 hours ago, Stilllearning said:

Mrs S uses the above batteries in the wireless mouse for her laptop. When her screen tells her that the batteries (two of them) have 52%  battery level, what exactly does this mean, and does it take into account the age of the battery, if it can still give out all the theoretically available power, etc. They do tend to go flat quicker than she likes or considers reasonable.

It will be a guesstimate based on the voltage. The problem with NiMh batteries (and NiCd) is that the nominal voltage is 1.2v. Whereas non-rechargeable batteries have a nominal voltage of 1.5v. So even with fully charged NiMh, the mouse will probably think they are partially flat and will probably give up with them before they are actually flat.

 

Decent alkaline batteries should last many months especially if it’s the type of mouse that you can fully switch off when not in use. I’d go with non-recharable alkalines.

[Stilllearning]

Thanks for those informative ideas, they have been passed on to Mrs S, who informs me that as the mouse works on a Bluetooth signal, and she turns off the laptop (mac) every night, she believes that the mouse is using no power overnight. 

[DHutch]

It will use something overnight, unless it has a switch on the underside, but likely not very much.

 

Is there a problem with the performance, or just curiosity? Different NiMH have different capacities from new and obviously with age degrades. They last well but if they are years old new ones may help. 

 

 

Daniel

[WotEver]

50 minutes ago, Stilllearning said:

Thanks for those informative ideas, they have been passed on to Mrs S, who informs me that as the mouse works on a Bluetooth signal, and she turns off the laptop (mac) every night, she believes that the mouse is using no power overnight. 

When she turns the Mac back on does she have to press anything on the mouse to get it seen?  Or does it just work?  If the latter then that demonstrates that it’s constantly signalling its presence and hence consuming batteries, even if it’s only using a little. 

[TheBiscuits]

3 hours ago, nicknorman said:

It will be a guesstimate based on the voltage. The problem with NiMh batteries (and NiCd) is that the nominal voltage is 1.2v. Whereas non-rechargeable batteries have a nominal voltage of 1.5v. So even with fully charged NiMh, the mouse will probably think they are partially flat and will probably give up with them before they are actually flat.

 

Decent alkaline batteries should last many months especially if it’s the type of mouse that you can fully switch off when not in use. I’d go with non-recharable alkalines.

I would disagree.

 

Yes, a lot of electronic devices would rather get 1.5V alakalines than 1.2V NiMH batteries, but I use a lot of NiMH rechargeables in nearly everything for treehugging reasons. 

 

It's not just that I'm a cheapskate and I get 1000 charges out of a £3 set of AAA batteries at all.  Even if that makes way more sense than paying £5 a go for alkalines ...

[dor]

My Hive sensors' documentation is very specific about using alkaline batteries and not to use NiMh batteries or other types of rechargeables.  Presumably because it will report that the batteries need changing even with relatively well-charged NiMhs.

[Mac of Cygnet]

So why are rechargables only 1.2v when full?  Can't they be made 1.5v like the ones they are meant to replace?

[TheBiscuits]

1 minute ago, Mac of Cygnet said:

So why are rechargables only 1.2v when full?  Can't they be made 1.5v like the ones they are meant to replace?

Not in a standard AAA or AA or C or D case.  The chemistry is different, so they would need to be bigger than the standard cell size for the same voltage.

[Mac of Cygnet]

1 hour ago, TheBiscuits said:

Not in a standard AAA or AA or C or D case.  The chemistry is different, so they would need to be bigger than the standard cell size for the same voltage.

 

But, but......     They are all the same voltage!    If you can get 1.2v into AAA size, couldn't you get 1.5v into AA and larger sizes?

 

OK, Google is my friend.  Nothing to do with size, just chemistry.  But you can now get 1.5v lithium rechargables.

Edited December 31, 2018 by Mac of Cygnet

[DandV]

9 minutes ago, Mac of Cygnet said:

 

But, but......     They are all the same voltage!    If you can get 1.2v into AAA size, couldn't you get 1.5v into AA and larger sizes?

The voltage of a single cell is entirely dictated by the chemistry. A lead acid single cell is 2v. The size of the cell dictates its capacity only. Higher voltages are obtained by connecting cells in series so the voltage of a multicell battery is the number of cells multiplied by voltage of a single cell of that chemistry. Hence 3volt lead acid batteries are not available. A D size Nicad battery will still only be 1.2volts.

[alan_fincher]

11 hours ago, Stilllearning said:

Thanks for those informative ideas, they have been passed on to Mrs S, who informs me that as the mouse works on a Bluetooth signal, and she turns off the laptop (mac) every night, she believes that the mouse is using no power overnight. 

This seems unlikely.

 

Does the mouse fully power itself off as the computer is shut down, (i.e. all indicator lights and the LED/laser completely unilluminated?

 

Even if that were the case, then, as has been suggested, if it "wakes up" when the computer is powered n, it must be using power because it is constantly monitoring for the wake up signal.

[nicknorman]

2 minutes ago, alan_fincher said:

This seems unlikely.

 

Does the mouse fully power itself off as the computer is shut down, (i.e. all indicator lights and the LED/laser completely unilluminated?

 

Even if that were the case, then, as has been suggested, if it "wakes up" when the computer is powered n, it must be using power because it is constantly monitoring for the wake up signal.

My mother (age 95) has a wireless mouse for her PC. Being brought up in the war, the first thing she did was to discover the on/off slider switch on the bottom of it, so switches it off when not in use. Not surprisingly the batteries have lasted several years!

[dor]

My wireless mouse on my main PC completely shuts down after about 30 minutes, even if the computer is left on.  After 30 minutes you have to give it a little shake to wake it up.  The standard 1.5V AA Duracell will last well over six months, and this is with several hours use most days.

[alan_fincher]

8 minutes ago, dor said:

My wireless mouse on my main PC completely shuts down after about 30 minutes, even if the computer is left on.  After 30 minutes you have to give it a little shake to wake it up.  The standard 1.5V AA Duracell will last well over six months, and this is with several hours use most days.

If a little shake will wake it up, isn't it possible it is using a very small amount of power waiting to detect that little shake.

 

As an aside, I bought a Bluetooth mouse of my son, without realising it actually used 2 x AAA batteries.  Even with a slider switch to turn it off, battery life is disappointingly short, (a few weeks only).  I notice the one he has now bought uses AA.  I think I may have "Mug" written on my forehead!

[dor]

15 minutes ago, alan_fincher said:

If a little shake will wake it up, isn't it possible it is using a very small amount of power waiting to detect that little shake.

 

If it does, it is too small for me to measure, so into microamps.  I don't think it is too difficult to make something that responds to movement without actively drawing current.  At least it is physically (think 1960s car alarms!) and I wouldn't think it would be hard to make something passive in an electronic circuit that would operate a switch with movement.

But even so, a single AA battery life of six months or more on a well-used device is something I can live with!

[Jess--]

most of the cordless mice I deal with need a button press to wake them up, cheapie alkaline batteries last about 9 months.

[DHutch]

13 hours ago, dor said:

My Hive sensors' documentation is very specific about using alkaline batteries and not to use NiMh batteries or other types of rechargeables.  Presumably because it will report that the batteries need changing even with relatively well-charged NiMhs.

Seems like poor design to me, which is a shame for such an relatively expensive piece of kit. 

 

Obviously there becomes a point where energy use is so low a disposable battery is more cost effective and or even environmentally friendly than a rechargeable and associated charging equipment.

 

However especially if you have setup from rechargeables with a good charger etc it seems a shame not to be able to use them in application such as a wireless thermostat. Presumably Hive Centrical/British Gas are more concerned with their device performance than with its ability to interface with rechargeable batteries.

 

 

Daniel

[Jess--]

27 minutes ago, DHutch said:

Seems like poor design to me, which is a shame for such an relatively expensive piece of kit. 

 

Obviously there becomes a point where energy use is so low a disposable battery is more cost effective and or even environmentally friendly than a rechargeable and associated charging equipment.

 

However especially if you have setup from rechargeables with a good charger etc it seems a shame not to be able to use them in application such as a wireless thermostat. Presumably Hive Centrical/British Gas are more concerned with their device performance than with its ability to interface with rechargeable batteries.

 

 

Daniel

A lot of the time it's down to expected lifespan from a set of batteries

the trouble with most rechargeable cells is they have a significant self discharge which can lead to some types going from fully charged to almost flat in under 6 months without being used, this isn't an issue if they are being used in something that will need them replacing every month or less but when you have them in equipment that should run for a year or more on a set of batteries you can find that you are losing more power to self discharge than the equipment is using.

it doesn't matter how good the equipment is, if a rechargeable battery flattens itself over a couple of months then a set of basic alkaline batteries will last several changes / charges of the rechargeables

 

 

[WotEver]

1 hour ago, DHutch said:

Seems like poor design to me, which is a shame for such an relatively expensive piece of kit. 

 

Obviously there becomes a point where energy use is so low a disposable battery is more cost effective and or even environmentally friendly than a rechargeable and associated charging equipment.

 

However especially if you have setup from rechargeables with a good charger etc it seems a shame not to be able to use them in application such as a wireless thermostat. Presumably Hive Centrical/British Gas are more concerned with their device performance than with its ability to interface with rechargeable batteries.

 

 

Daniel

Our Hive stat is still on its original (alkaline) batteries nearly a year after installation. With a power requirement that low I see no point in using rechargeables. 

29 minutes ago, Jess-- said:

the trouble with most rechargeable cells is they have a significant self discharge which can lead to some types going from fully charged to almost flat in under 6 months...

Agreed

[zenataomm]

19 hours ago, Stilllearning said:

Thanks for those informative ideas, they have been passed on to Mrs S, who informs me that as the mouse works on a Bluetooth signal, and she turns off the laptop (mac) every night, she believes that the mouse is using no power overnight. 

So, did she also believe she could leave the TV on after The Epilogue finished?

[Stilllearning]

15 hours ago, zenataomm said:

So, did she also believe she could leave the TV on after The Epilogue finished?

Back in the days of the Epilogue you turned off the tv and it actually was “off”. Now it is on standby and still consuming power, does anyone know how much?