Do NiMh batteries self discharge if left unused for a period of time, or is
this just a myth?


--
Dave - The Medway Handyman
www.medwayhandyman.co.uk

In article ,
The Medway Handyman wrote:
Do NiMh batteries self discharge if left unused for a period of time, or
is this just a myth?

They do - as do Ni-Cads. But by how much seems to vary wildly by make. Or
whatever. In other words you could have some which appear to take a full
charge and last ok when used near immediately - but discharge very quickly
when not used, as it were.

--
*What hair colour do they put on the driver's license of a bald man? *

Dave Plowman London SW
To e-mail, change noise into sound.

On Tue, 24 Nov 2009 00:26:45 GMT, "The Medway Handyman"
wrote:

Do NiMh batteries self discharge if left unused for a period of time, or is
this just a myth?


Two articles here. The freezer bit is interesting.

http://www.greenbatteries.com/nibafa.html

In message , The Medway
Handyman writes
Do NiMh batteries self discharge if left unused for a period of time,

Yes, fairly quickly as well - can be noticeable in a matter of weeks?.
Though the newer type with a lower self discharge rate really do hold
charge a lot better. (Sanyo eneloop, Uniross Hybrio etc.) which is why
they can sell them ready charged.

or is
this just a myth?

No.

Except for thing like the digital cameras, where we tend to cycle
batteries pretty frequently anyway. I'm finding that I'm moving over to
the lower self discharge rate ones when I get new ones. for general use
I find them more convenient and they last a decent amount of time in low
current drain applications.
--
Chris French

We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember "The Medway Handyman"
saying something like:

Do NiMh batteries self discharge if left unused for a period of time, or is
this just a myth?

Up to three months if left unused to the point where they're no use when
you go to switch on a camera, etc.

The Medway Handyman wrote:
Do NiMh batteries self discharge if left unused for a period of time, or is
this just a myth?


yes. Bloody quickly too. It gets worse with age..

On 24 Nov, 02:24, The Natural Philosopher
wrote:
The Medway Handyman wrote:
Do NiMh batteries self discharge if left unused for a period of time, or is
this just a myth?

yes. Bloody quickly too. It gets worse with age..

Doesn't everything !

On Nov 24, 10:06*am, robgraham wrote:
On 24 Nov, 02:24, The Natural Philosopher
wrote:

The Medway Handyman wrote:
Do NiMh batteries self discharge if left unused for a period of time, or is
this just a myth?

yes. Bloody quickly too. It gets worse with age..

Doesn't everything !

I think 1% charge loss per day is normal for an NiMh; personally I've
switched to eneloops which do seem to retain charge as advertised.

I think 1% charge loss per day is normal for an NiMh; personally I've
switched to eneloops which do seem to retain charge as advertised.

The only trouble with the Eneloops, Vapex Instant's, etc. is that the
capacity is much lower (e.g., 2000mah v. 2900mah), giving a much
shorter run-time. I'm not aware of any power tools using the Eneloop-
style batteries yet, but I imagine that power tool manufacturers would
rather have the higher capacity and longer run-times, than longer on-
the-shelf time?

dan.

In article
,
dent wrote:
The only trouble with the Eneloops, Vapex Instant's, etc. is that the
capacity is much lower (e.g., 2000mah v. 2900mah), giving a much
shorter run-time. I'm not aware of any power tools using the Eneloop-
style batteries yet, but I imagine that power tool manufacturers would
rather have the higher capacity and longer run-times, than longer on-
the-shelf time?

Really, if self discharge is a problem on a little used cordless tool
wouldn't a mains one make more sense?

--
*Puritanism: The haunting fear that someone, somewhere may be happy.

Dave Plowman London SW
To e-mail, change noise into sound.

On Nov 24, 4:39*am, dent wrote:
I think 1% charge loss per day is normal for an NiMh; personally I've
switched to eneloops which do seem to retain charge as advertised.

The only trouble with the Eneloops, Vapex Instant's, etc. is that the
capacity is much lower (e.g., 2000mah v. 2900mah), giving a much
shorter run-time. I'm not aware of any power tools using the Eneloop-
style batteries yet, but I imagine that power tool manufacturers would
rather have the higher capacity and longer run-times, than longer on-
the-shelf time?

dan.

I dont find actual runtime less since they are not in my charger as
much. With every charge you get less life, with eneloop after 2 years
I am happy, my regular Nimh after 2 years have noticably less life
compared to eneloop. Sanyos ratings on capacity I trust other off
brands stating 2900 mah often are overstated. Try Eneloop, I read a
new eneloop is or will soon be out with that will last even longer, my
regular Nimh deteriorated very fast and are junk. When I used to turn
on a camera with regular nimh It was always near dead, now with
eneloops its not an issue anymore, my camera just works after sitting
3-6 months. I used to waste alot of time charging.

On 24 Nov, 12:45, ransley wrote:
On Nov 24, 4:39*am, dent wrote:

I think 1% charge loss per day is normal for an NiMh; personally I've
switched to eneloops which do seem to retain charge as advertised.

The only trouble with the Eneloops, Vapex Instant's, etc. is that the
capacity is much lower (e.g., 2000mah v. 2900mah), giving a much
shorter run-time. I'm not aware of any power tools using the Eneloop-
style batteries yet, but I imagine that power tool manufacturers would
rather have the higher capacity and longer run-times, than longer on-
the-shelf time?

dan.

I dont find actual runtime less since they are not in my charger as
much. With every charge you get less life, with eneloop after 2 years
I am happy, my regular Nimh after 2 years have noticably less life
compared to eneloop. Sanyos ratings on capacity I trust other off
brands stating 2900 mah often are overstated.

That's very true. I use them mainly for my LED bike lights, where one
set of 2900mah last me two days. Add in other uses (head torch, etc.)
and over the course of a winter each set of batteries get an awful lot
of fairly deep discharge/recharge cycles. Most brands I've tried die
very quickly but I still have Vapextech batteries which are three
years old, and still hold enough charge for the magic two days of use
though. The Eneloop or Instant ones at 2000mah don't quite enough
capacity to last 2 days though, so I would have to charge them every
day.

I read a new eneloop is or will soon be out with that will last even longer

I look forward to that. Over the summer months when my lights get less
use I still have to charge them every 2-3 weeks even if they aren't
used, and avoiding that would be good.

dan.

On Nov 24, 7:26*am, dent wrote:
On 24 Nov, 12:45, ransley wrote:





On Nov 24, 4:39*am, dent wrote:

I think 1% charge loss per day is normal for an NiMh; personally I've
switched to eneloops which do seem to retain charge as advertised.

The only trouble with the Eneloops, Vapex Instant's, etc. is that the
capacity is much lower (e.g., 2000mah v. 2900mah), giving a much
shorter run-time. I'm not aware of any power tools using the Eneloop-
style batteries yet, but I imagine that power tool manufacturers would
rather have the higher capacity and longer run-times, than longer on-
the-shelf time?

dan.

I dont find actual runtime less since they are not in my charger as
much. With every charge you get less life, with eneloop after 2 years
I am happy, my regular Nimh after 2 years have noticably less life
compared to eneloop. Sanyos ratings on capacity I trust other off
brands stating 2900 mah often are overstated.

That's very true. I use them mainly for my LED bike lights, where one
set of 2900mah last me two days. Add in other uses (head torch, etc.)
and over the course of a winter each set of batteries get an awful lot
of fairly deep discharge/recharge cycles. Most brands I've tried die
very quickly but I still have Vapextech batteries which are three
years old, and still hold enough charge for the magic two days of use
though. The Eneloop or Instant ones at 2000mah don't quite enough
capacity to last 2 days though, so I would have to charge them every
day.

I read a new eneloop is or will soon be out with that will last even longer

I look forward to that. Over the summer months when my lights get less
use I still have to *charge them every 2-3 weeks even if they aren't
used, and avoiding that would be good.

dan.- Hide quoted text -

- Show quoted text -

I think the new eneloops last longer by allowing more recharges, 1000
vs 600, I use regular alkaline batteries in my Led bike and regular
lights and go all summer, I think 300 hours is what mine are rated
at , but they are not real bright so maybe that is why.

The Medway Handyman wrote on 24/11/2009 :
Do NiMh batteries self discharge if left unused for a period of time, or is
this just a myth?

Over days, weeks or months - yes. How well they retain the charge seems
to depend in part on luck, rather than how much you paid for them.
Keeping them in a plastic bag in the fridge, is supposed to help.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

On Tue, 24 Nov 2009 00:43:34 +0000 (GMT), Dave Plowman (News) wrote:

In article ,
The Medway Handyman wrote:
Do NiMh batteries self discharge if left unused for a period of time, or
is this just a myth?

They do - as do Ni-Cads. But by how much seems to vary wildly by make. Or
whatever. In other words you could have some which appear to take a full
charge and last ok when used near immediately - but discharge very quickly
when not used, as it were.

Newer ones will retain significant charge for up to a year. The ones that
come pre-charged are normally that type. Hybrio was one make, now
superceded by uniross ultra.

They are more expensive, but I find them useful for a backup set.

--
B Thumbs

On Wed, 25 Nov 2009 11:29:49 +0000, BD wrote:

On Tue, 24 Nov 2009 00:43:34 +0000 (GMT), Dave Plowman (News) wrote:

In article ,
The Medway Handyman wrote:
Do NiMh batteries self discharge if left unused for a period of time, or
is this just a myth?

They do - as do Ni-Cads. But by how much seems to vary wildly by make. Or
whatever. In other words you could have some which appear to take a full
charge and last ok when used near immediately - but discharge very quickly
when not used, as it were.

Newer ones will retain significant charge for up to a year. The ones that
come pre-charged are normally that type. Hybrio was one make, now
superceded by uniross ultra.

They are more expensive, but I find them useful for a backup set.

7-Day Shop is doing its own brand of these at a couple of quid less.

I saw somewhere a test that showed the 2100mAh hybrid cells outlasting NiMH
of nominally higher energy when used in a camera - can't remember the
details.

http://www.7dayshop.com/catalog/defa... =SEARCH&comp=
--
Peter.
The head of a pin will hold more angels if
it's been flattened with an angel-grinder.

On Wed, 25 Nov 2009 13:48:00 +0000, PeterC
wrote:

On Wed, 25 Nov 2009 11:29:49 +0000, BD wrote:

On Tue, 24 Nov 2009 00:43:34 +0000 (GMT), Dave Plowman (News) wrote:

In article ,
The Medway Handyman wrote:
Do NiMh batteries self discharge if left unused for a period of time, or
is this just a myth?

They do - as do Ni-Cads. But by how much seems to vary wildly by make. Or
whatever. In other words you could have some which appear to take a full
charge and last ok when used near immediately - but discharge very quickly
when not used, as it were.

Newer ones will retain significant charge for up to a year. The ones that
come pre-charged are normally that type. Hybrio was one make, now
superceded by uniross ultra.

They are more expensive, but I find them useful for a backup set.

7-Day Shop is doing its own brand of these at a couple of quid less.

I saw somewhere a test that showed the 2100mAh hybrid cells outlasting NiMH
of nominally higher energy when used in a camera - can't remember the
details.


One factor AIUI is that some higher energy batteries eg Energizer,
have a high internal resistance, so it doesn't take long in some
instances for them to be unable to power the device they've been
installed in. I nearly threw away a digital camera because it would
only last a few seconds with new batteries. I bought even higher
capacity Energizers and it still would only last a few seconds. I
bought Sanyo Eneloops and it now goes for months.


--
AnthonyL