Using Li-Ion batteries.

[Ian Field]

With NiMh, its accustomed practice to give the cells a few charge cycles to
work up to their full performance - does the same apply to Li-Ion?

Recently I bought a 3W Li-Ion LED handlamp and I've spent more time
recharging the battery than actually using it! Every time I've gone to use
it I've found that the battery has self discharged and is totally flat.

Although there is no mention of full charge cycling in the instruction
booklet, I tried charging it then running it down in a single session to
cycle the battery - there seems to be some improvement, but its still too
soon to tell for sure.

Any comments on the correct care of Li-Ion batteries are welcome.

Thanks.

 

On Fri, 1 Feb 2013 18:17:33 -0000, "Ian Field"
<gangprobing.alien@ntlworld.com> wrote:

With NiMh, its accustomed practice to give the cells a few charge cycles to
work up to their full performance - does the same apply to Li-Ion?

Recently I bought a 3W Li-Ion LED handlamp and I've spent more time
recharging the battery than actually using it! Every time I've gone to use
it I've found that the battery has self discharged and is totally flat.

That shouldn't happen. The self-discharge of LiIon batteries should
be measured in years. At the PPoE, after four years on the shelf we
found "new" batteries still had over half charge.

Although there is no mention of full charge cycling in the instruction
booklet, I tried charging it then running it down in a single session to
cycle the battery - there seems to be some improvement, but its still too
soon to tell for sure.

Cycling LiIon batteries is often recommended but not so much to
condition the battery as to reset/calibrate the charging circuit.
Laptops, in particular, track the charge of batteries and the charger
needs to learn a "new" battery. The cells themselves don't need any
"reforming" or anything.

Any comments on the correct care of Li-Ion batteries are welcome.

They're really pretty simple to use but don't take gross abuse well.
It sounds like you have a defective battery or perhaps more likely, a
defective appliance.

 

[asdf]

On Fri, 01 Feb 2013 18:17:33 +0000, Ian Field wrote:

Recently I bought a 3W Li-Ion LED handlamp and I've spent more time
recharging the battery than actually using it! Every time I've gone to
use it I've found that the battery has self discharged and is totally
flat.

How much time goes between last recharge and when you find it flat?
Lithium based batteries should have a much longer self discharge rate
compared to NiMh ones. This may indicate che battery is either crap or
defective. The safety circuit also may be eating power for no reason.

Any comments on the correct care of Li-Ion batteries are welcome.

Lots of information here.
http://batteryuniversity.com/

 

[Ian Field]

"asdf" <asdf@nospam.com> wrote in message
news:keh2vq$819$1@speranza.aioe.org...

On Fri, 01 Feb 2013 18:17:33 +0000, Ian Field wrote:

Recently I bought a 3W Li-Ion LED handlamp and I've spent more time
recharging the battery than actually using it! Every time I've gone to
use it I've found that the battery has self discharged and is totally
flat.

How much time goes between last recharge and when you find it flat?
Lithium based batteries should have a much longer self discharge rate
compared to NiMh ones. This may indicate che battery is either crap or
defective. The safety circuit also may be eating power for no reason.

Maybe 2-3 weeks, I'd expect the battery to stay up a lot longer than that!

The instructions warn to disconnect the wall-wart from the lamp when not
charging, to prevent discharge - but when its not brought in for charging,
the lamp is in the lock up garage far from the wall wart.

It says 3 yr warranty on the box and I'm well within the statutory 1 yr, if
having cycled the battery shows no improvement, I can decide to return it or
write off the loss & indulge in a bit of reverse engineering.

 

[Ian Field]

<krw@attt.bizz> wrote in message
news:626og850qr4fpq4b3akk9c3g309etcj9mk@4ax.com...

On Fri, 1 Feb 2013 18:17:33 -0000, "Ian Field"
gangprobing.alien@ntlworld.com> wrote:

With NiMh, its accustomed practice to give the cells a few charge cycles
to
work up to their full performance - does the same apply to Li-Ion?

Recently I bought a 3W Li-Ion LED handlamp and I've spent more time
recharging the battery than actually using it! Every time I've gone to use
it I've found that the battery has self discharged and is totally flat.

That shouldn't happen. The self-discharge of LiIon batteries should
be measured in years. At the PPoE, after four years on the shelf we
found "new" batteries still had over half charge.

Although there is no mention of full charge cycling in the instruction
booklet, I tried charging it then running it down in a single session to
cycle the battery - there seems to be some improvement, but its still too
soon to tell for sure.

Cycling LiIon batteries is often recommended but not so much to
condition the battery as to reset/calibrate the charging circuit.
Laptops, in particular, track the charge of batteries and the charger
needs to learn a "new" battery. The cells themselves don't need any
"reforming" or anything.

The instructions say its protected from overcharging - but nontheless
shouldn't be left charging for long periods after the charge indicator LED
changes from red to green.

When I cycled the battery - towards the end of discharge I could hear the
oscillator whine getting lower, AFAIK there is no indicator of excessive
discharge, I didn't continue the discharge to see if there's an automatic
UVLO, as I understand that Li-Ion won't recharge if over discharged.

 

[Peter]

On Fri, 01 Feb 2013 14:38:10 -0500, krw@attt.bizz wrote:

On Fri, 1 Feb 2013 18:17:33 -0000, "Ian Field"
gangprobing.alien@ntlworld.com> wrote:

With NiMh, its accustomed practice to give the cells a few charge cycles to
work up to their full performance - does the same apply to Li-Ion?

Recently I bought a 3W Li-Ion LED handlamp and I've spent more time
recharging the battery than actually using it! Every time I've gone to use
it I've found that the battery has self discharged and is totally flat.

That shouldn't happen. The self-discharge of LiIon batteries should
be measured in years. At the PPoE, after four years on the shelf we
found "new" batteries still had over half charge.

Although there is no mention of full charge cycling in the instruction
booklet, I tried charging it then running it down in a single session to
cycle the battery - there seems to be some improvement, but its still too
soon to tell for sure.

Cycling LiIon batteries is often recommended but not so much to
condition the battery as to reset/calibrate the charging circuit.
Laptops, in particular, track the charge of batteries and the charger
needs to learn a "new" battery. The cells themselves don't need any
"reforming" or anything.

Any comments on the correct care of Li-Ion batteries are welcome.

They're really pretty simple to use but don't take gross abuse well.
It sounds like you have a defective battery or perhaps more likely, a
defective appliance.

Or a defective battery charger

 

[Ian Field]

"Peter" <peter@arin.htlm.com> wrote in message
news9eog81f3rl69r12he20rltu4l9agijkmr@4ax.com...

On Fri, 01 Feb 2013 14:38:10 -0500, krw@attt.bizz wrote:

On Fri, 1 Feb 2013 18:17:33 -0000, "Ian Field"
gangprobing.alien@ntlworld.com> wrote:

With NiMh, its accustomed practice to give the cells a few charge cycles
to
work up to their full performance - does the same apply to Li-Ion?

Recently I bought a 3W Li-Ion LED handlamp and I've spent more time
recharging the battery than actually using it! Every time I've gone to
use
it I've found that the battery has self discharged and is totally flat.

That shouldn't happen. The self-discharge of LiIon batteries should
be measured in years. At the PPoE, after four years on the shelf we
found "new" batteries still had over half charge.

Although there is no mention of full charge cycling in the instruction
booklet, I tried charging it then running it down in a single session to
cycle the battery - there seems to be some improvement, but its still too
soon to tell for sure.

Cycling LiIon batteries is often recommended but not so much to
condition the battery as to reset/calibrate the charging circuit.
Laptops, in particular, track the charge of batteries and the charger
needs to learn a "new" battery. The cells themselves don't need any
"reforming" or anything.

Any comments on the correct care of Li-Ion batteries are welcome.

They're really pretty simple to use but don't take gross abuse well.
It sounds like you have a defective battery or perhaps more likely, a
defective appliance.

Or a defective battery charger

I think the wall wart is the same as supplied for that store-chain's "stick"
type LED worklight with NiMh batteries - AFAIK all the electronics for
controlling charge to the Li-Ion are in the lamp.

 

[asdf]

On Fri, 01 Feb 2013 21:42:16 +0000, Ian Field wrote:

Maybe 2-3 weeks, I'd expect the battery to stay up a lot longer than
that!

Yes, it should be definitely more than that.
Is the battery easily replaceable without voiding the warranty?

The instructions warn to disconnect the wall-wart from the lamp when not
charging, to prevent discharge

Huh? I would expect at least a diode in series to protect the wall-wart
and/or the battery. If they had to save one diode they probably went also
for a cheap safety circuit. Just speculation, though it would explain
something.

if having cycled the battery shows no improvement, I can decide to
return it or write off the loss & indulge in a bit of reverse
engineering.

I would return it too.

 

[Mike S.]

In article <NLWOs.102108$C05.77717@fx31.fr7>,
Ian Field <gangprobing.alien@ntlworld.com> wrote:

krw@attt.bizz> wrote in message
news:626og850qr4fpq4b3akk9c3g309etcj9mk@4ax.com...
On Fri, 1 Feb 2013 18:17:33 -0000, "Ian Field"
gangprobing.alien@ntlworld.com> wrote:

With NiMh, its accustomed practice to give the cells a few charge cycles
to
work up to their full performance - does the same apply to Li-Ion?

Recently I bought a 3W Li-Ion LED handlamp and I've spent more time
recharging the battery than actually using it! Every time I've gone to use
it I've found that the battery has self discharged and is totally flat.

That shouldn't happen. The self-discharge of LiIon batteries should
be measured in years. At the PPoE, after four years on the shelf we
found "new" batteries still had over half charge.

Although there is no mention of full charge cycling in the instruction
booklet, I tried charging it then running it down in a single session to
cycle the battery - there seems to be some improvement, but its still too
soon to tell for sure.

Cycling LiIon batteries is often recommended but not so much to
condition the battery as to reset/calibrate the charging circuit.
Laptops, in particular, track the charge of batteries and the charger
needs to learn a "new" battery. The cells themselves don't need any
"reforming" or anything.

The instructions say its protected from overcharging - but nontheless
shouldn't be left charging for long periods after the charge indicator LED
changes from red to green.

When I cycled the battery - towards the end of discharge I could hear the
oscillator whine getting lower, AFAIK there is no indicator of excessive
discharge, I didn't continue the discharge to see if there's an automatic
UVLO, as I understand that Li-Ion won't recharge if over discharged.

Is the battery removeable? For a flashlight I'd guess yes.

The behavior and danger of overcharging and overdischarging depends on
whether the cell has a protection circuit. If it's a cylindrical cell,
it's easy to tell as it's a thin metallic disc shrink-wrapped on the end
of the cell.

Even if the cell or charger protects against overcharging, it is not a
good idea to leave it charging indefinitely as the heat generated will
eventually degrade the cell. Conditions of high temperature and high
voltage are the most harmful to LiIon cells.

Protection against overdischarging is necessary because below ~1v or so
the copper electrode will go into solution. If such a cell is charged
again, the copper then turns back to metal within the electrolyte, forming
shunts that act as short-circuits leading to explosion.

The over-discharge behavior depends on whether there is a protection
circuit. A protected cell will typicially cut off at ~2.5V and go to
sleep; a "smart" charger will refuse to charge it until the protection
circuit is awakened by force-charging it momentarily at low current.
Of course, by doing that you assume all risk if the cell's voltage is
really much lower than 2.5V.

An unprotected cell will keep putting out juice for longer, leading to an
over-discharged cell that is dangerous to charge again.

 

[Ian Field]

"asdf" <asdf@nospam.com> wrote in message
news:kehnc7$vl4$1@speranza.aioe.org...

On Fri, 01 Feb 2013 21:42:16 +0000, Ian Field wrote:

Maybe 2-3 weeks, I'd expect the battery to stay up a lot longer than
that!

Yes, it should be definitely more than that.
Is the battery easily replaceable without voiding the warranty?

The instructions warn to disconnect the wall-wart from the lamp when not
charging, to prevent discharge

Huh? I would expect at least a diode in series to protect the wall-wart
and/or the battery. If they had to save one diode they probably went also
for a cheap safety circuit. Just speculation, though it would explain
something.

if having cycled the battery shows no improvement, I can decide to
return it or write off the loss & indulge in a bit of reverse
engineering.

I would return it too.

Learning usually comes at a cost - I could write off the loss and see what I
could learn reverse engineering the inverter.

A 3W LED would also be a welcome addition to the junk box - not a cost
effective trade in this instance, but I do get the reflector & mounting
thrown in.

I still have the option to return it, but if I get a lithium fire, I'll
definately be having words with the retailer!

 

[legg]

On Fri, 1 Feb 2013 21:49:46 -0000, "Ian Field"
<gangprobing.alien@ntlworld.com> wrote:

snip

When I cycled the battery - towards the end of discharge I could hear the
oscillator whine getting lower, AFAIK there is no indicator of excessive
discharge, I didn't continue the discharge to see if there's an automatic
UVLO, as I understand that Li-Ion won't recharge if over discharged.

Audibility of a charger is a fair indication of defect in either the
charger or load.

RL

 

[Ian Field]

"Mike S." <retsuhcs@xinap.moc> wrote in message
news:kehoke$pjh$2@reader1.panix.com...

In article <NLWOs.102108$C05.77717@fx31.fr7>,
Ian Field <gangprobing.alien@ntlworld.com> wrote:


krw@attt.bizz> wrote in message
news:626og850qr4fpq4b3akk9c3g309etcj9mk@4ax.com...
On Fri, 1 Feb 2013 18:17:33 -0000, "Ian Field"
gangprobing.alien@ntlworld.com> wrote:

With NiMh, its accustomed practice to give the cells a few charge cycles
to
work up to their full performance - does the same apply to Li-Ion?

Recently I bought a 3W Li-Ion LED handlamp and I've spent more time
recharging the battery than actually using it! Every time I've gone to
use
it I've found that the battery has self discharged and is totally flat.

That shouldn't happen. The self-discharge of LiIon batteries should
be measured in years. At the PPoE, after four years on the shelf we
found "new" batteries still had over half charge.

Although there is no mention of full charge cycling in the instruction
booklet, I tried charging it then running it down in a single session to
cycle the battery - there seems to be some improvement, but its still
too
soon to tell for sure.

Cycling LiIon batteries is often recommended but not so much to
condition the battery as to reset/calibrate the charging circuit.
Laptops, in particular, track the charge of batteries and the charger
needs to learn a "new" battery. The cells themselves don't need any
"reforming" or anything.

The instructions say its protected from overcharging - but nontheless
shouldn't be left charging for long periods after the charge indicator LED
changes from red to green.

When I cycled the battery - towards the end of discharge I could hear the
oscillator whine getting lower, AFAIK there is no indicator of excessive
discharge, I didn't continue the discharge to see if there's an automatic
UVLO, as I understand that Li-Ion won't recharge if over discharged.

Is the battery removeable? For a flashlight I'd guess yes.

The behavior and danger of overcharging and overdischarging depends on
whether the cell has a protection circuit. If it's a cylindrical cell,
it's easy to tell as it's a thin metallic disc shrink-wrapped on the end
of the cell.

Even if the cell or charger protects against overcharging, it is not a
good idea to leave it charging indefinitely as the heat generated will
eventually degrade the cell. Conditions of high temperature and high
voltage are the most harmful to LiIon cells.

Protection against overdischarging is necessary because below ~1v or so
the copper electrode will go into solution. If such a cell is charged
again, the copper then turns back to metal within the electrolyte, forming
shunts that act as short-circuits leading to explosion.

The over-discharge behavior depends on whether there is a protection
circuit. A protected cell will typicially cut off at ~2.5V and go to
sleep; a "smart" charger will refuse to charge it until the protection
circuit is awakened by force-charging it momentarily at low current.
Of course, by doing that you assume all risk if the cell's voltage is
really much lower than 2.5V.

An unprotected cell will keep putting out juice for longer, leading to an
over-discharged cell that is dangerous to charge again.

A few good points to take noteof there.

Its a pistol grip lamp with a 3W LED main beam plus a low power ring of LEDs
around the rim of the reflector & a panel of LED on the side for "map
reading".

None of the internal parts are accessible without voiding the warranty.

 

[Ian Field]

"legg" <legg@nospam.magma.ca> wrote in message
news:asbqg8to90ebmdccg1habkm069l7ju2oqu@4ax.com...

On Fri, 1 Feb 2013 21:49:46 -0000, "Ian Field"
gangprobing.alien@ntlworld.com> wrote:



snip

When I cycled the battery - towards the end of discharge I could hear the
oscillator whine getting lower, AFAIK there is no indicator of excessive
discharge, I didn't continue the discharge to see if there's an automatic
UVLO, as I understand that Li-Ion won't recharge if over discharged.

Audibility of a charger is a fair indication of defect in either the
charger or load.

Well it run for longer than the claimed endurance when I tried cycling the
battery, so there can't be that much wrong with the charge circuit or
inverter.

Discovering whether self discharge takes a decent length of time - takes a
decent length of time!

 

[BEN]

responding to
http://www.electrondepot.com/components/using-li-ion-batteries-33340-.htm ,
BEN wrote:

gangprobing.alien wrote:

With NiMh, its accustomed practice to give the cells a few charge cycles
to
work up to their full performance - does the same apply to Li-Ion?

Recently I bought a 3W Li-Ion LED handlamp and I've spent more time
recharging the battery than actually using it! Every time I've gone to
use
it I've found that the battery has self discharged and is totally flat.

Although there is no mention of full charge cycling in the instruction
booklet, I tried charging it then running it down in a single session to

cycle the battery - there seems to be some improvement, but its still
too
soon to tell for sure.

Any comments on the correct care of Li-Ion batteries are welcome.

Thanks.

What type of battery is it. cyl 18650? I have several flashlights that use
18650. 1000 lumens to 6000 lumens. None of the batteries discharge
whatsoever. Many of these flashlights use an LED voltage controller (driver )
It may be defective draining the battery, but the battery should not be
connected if the switch is off..!!! I purchased mine from a china market and
they will hold voltage for at least a month with a Vdrop of less than 10
percent Will the battery go flat if not in the flashlight? If so bad battery
or the built in battery charge controller is bad.
Ben

 

[Ian Field]

"BEN" <f6ceedb9c75b52f7fcc0a55cf0cfbf5d_984@example.com> wrote in message
news:99453$5394a918$43de0cc0$31701@news.flashnewsgroups.com...

responding to
http://www.electrondepot.com/components/using-li-ion-batteries-33340-.htm
,
BEN wrote:
gangprobing.alien wrote:

With NiMh, its accustomed practice to give the cells a few charge cycles
to work up to their full performance - does the same apply to Li-Ion?
Recently I bought a 3W Li-Ion LED handlamp and I've spent more time
recharging the battery than actually using it! Every time I've gone to
use it I've found that the battery has self discharged and is totally
flat. Although there is no mention of full charge cycling in the
instruction booklet, I tried charging it then running it down in a
single session to
cycle the battery - there seems to be some improvement, but its still
too soon to tell for sure. Any comments on the correct care of Li-Ion
batteries are welcome. Thanks.

What type of battery is it. cyl 18650? I have several flashlights that
use
18650. 1000 lumens to 6000 lumens. None of the batteries discharge
whatsoever.

Haven't opened it to have a look - presumably it will eventually deteriorate
to not very long running time.

Allegedly, it has a 3-yr warranty and I still have the box it came in, but
its a Lidl stores weekly offer that I'd have to wait for them to come around
again.

It has a 2200mAh battery which it claims should run the 5W LED spot light
for 2-hrs.

 

[Ben]

responding to
http://www.electrondepot.com/components/using-li-ion-batteries-33340-.htm ,
Ben wrote:

gangprobing.alien wrote:



"BEN"
wrote in message
news:99453$5394a918$43de0cc0$31701@news.flashnewsgroups.com...
responding to

http://www.electrondepot.com/components/using-li-ion-batteries-33340-.htm

,
BEN wrote:
gangprobing.alien wrote:

With NiMh, its accustomed practice to give the cells a few
charge cycles
to work up to their full performance - does the same apply to
Li-Ion?
Recently I bought a 3W Li-Ion LED handlamp and I've spent more
time
recharging the battery than actually using it! Every time I've
gone to
use it I've found that the battery has self discharged and is
totally
flat. Although there is no mention of full charge cycling in
the
instruction booklet, I tried charging it then running it down
in a
single session to
cycle the battery - there seems to be some improvement, but
its still
too soon to tell for sure. Any comments on the correct care of
Li-Ion
batteries are welcome. Thanks.

What type of battery is it. cyl 18650? I have several flashlights
that
use
18650. 1000 lumens to 6000 lumens. None of the batteries discharge

whatsoever.

Haven't opened it to have a look - presumably it will eventually
deteriorate
to not very long running time.

Allegedly, it has a 3-yr warranty and I still have the box it came in,
but
its a Lidl stores weekly offer that I'd have to wait for them to come
around
again.

It has a 2200mAh battery which it claims should run the 5W LED spot
light
for 2-hrs.

If you have a voltmeter charge up the battery for the normal charge time.
Measure the voltage. It should measure about 4.22 vdc. If it doesn't there
is something wrong with the charger or the battery. After a week it should
measure about 3.7v. The Chinese ones I purchased hold 3.4 after one month and
I have heard that they are seconds from major manufacturers, but thet work
well in my high power flashlights. Also I use the special dual cell charger
that they come with. If you have a multimeter you can remove the end cap
switch and measure the current the flashlight.
One of the flashlights I have has a slide switch which allows an infinite
number of brightness settings. If I turn off the flashlight with the slide
switch the battery will run down because a small amount of current is
flowing. So I have to unscrew the tail cap when I shut off the light. Then the
flashlight does not discharge the battery

 

[Charlie+]

On Sun, 8 Jun 2014 20:28:14 +0100, "Ian Field"
<gangprobing.alien@ntlworld.com> wrote as underneath :

"BEN" <f6ceedb9c75b52f7fcc0a55cf0cfbf5d_984@example.com> wrote in message
news:99453$5394a918$43de0cc0$31701@news.flashnewsgroups.com...
responding to
http://www.electrondepot.com/components/using-li-ion-batteries-33340-.htm
,
BEN wrote:
gangprobing.alien wrote:

With NiMh, its accustomed practice to give the cells a few charge cycles
to work up to their full performance - does the same apply to Li-Ion?
Recently I bought a 3W Li-Ion LED handlamp and I've spent more time
recharging the battery than actually using it! Every time I've gone to
use it I've found that the battery has self discharged and is totally
flat. Although there is no mention of full charge cycling in the
instruction booklet, I tried charging it then running it down in a
single session to
cycle the battery - there seems to be some improvement, but its still
too soon to tell for sure. Any comments on the correct care of Li-Ion
batteries are welcome. Thanks.

What type of battery is it. cyl 18650? I have several flashlights that
use
18650. 1000 lumens to 6000 lumens. None of the batteries discharge
whatsoever.

Haven't opened it to have a look - presumably it will eventually deteriorate
to not very long running time.

Allegedly, it has a 3-yr warranty and I still have the box it came in, but
its a Lidl stores weekly offer that I'd have to wait for them to come around
again.

It has a 2200mAh battery which it claims should run the 5W LED spot light
for 2-hrs.

Id write to the warrantee people, Lidl are very good about genuine
complaints in my experience, they might just send you another one FOC
without requiring return, say you cant open it to find what the problem
is because of warrantee void! C+

 

[Ian Field]

"Ben" <f6ceedb9c75b52f7fcc0a55cf0cfbf5d_984@example.com> wrote in message
news:4da81$5397a03a$43de0cc0$14161@news.flashnewsgroups.com...

responding to
http://www.electrondepot.com/components/using-li-ion-batteries-33340-.htm
,
Ben wrote:
gangprobing.alien wrote:



"BEN" wrote in message
news:99453$5394a918$43de0cc0$31701@news.flashnewsgroups.com...
responding to
http://www.electrondepot.com/components/using-li-ion-batteries-33340-.htm

, BEN wrote:
gangprobing.alien wrote: With NiMh, its accustomed practice to give
the cells a few
charge cycles
to work up to their full performance - does the same apply to
Li-Ion?
Recently I bought a 3W Li-Ion LED handlamp and I've spent more
time
recharging the battery than actually using it! Every time I've
gone to
use it I've found that the battery has self discharged and is
totally
flat. Although there is no mention of full charge cycling in
the
instruction booklet, I tried charging it then running it down
in a
single session to
cycle the battery - there seems to be some improvement, but
its still
too soon to tell for sure. Any comments on the correct care of
Li-Ion
batteries are welcome. Thanks.

What type of battery is it. cyl 18650? I have several flashlights
that
use 18650. 1000 lumens to 6000 lumens. None of the batteries discharge

whatsoever.

Haven't opened it to have a look - presumably it will eventually
deteriorate to not very long running time. Allegedly, it has a 3-yr
warranty and I still have the box it came in,
but its a Lidl stores weekly offer that I'd have to wait for them to
come
around again. It has a 2200mAh battery which it claims should run the 5W
LED spot
light for 2-hrs.
If you have a voltmeter charge up the battery for the normal charge time.
Measure the voltage. It should measure about 4.22 vdc. If it doesn't
there
is something wrong with the charger or the battery.

Its 3yr warranty hasn't expired yet so I'm resisting the temptation to open
it up.

It was on the Lidl store weekly offers, so I have to wait for them to come
around again to get a replacement rather than refund.

For the time being, the battery stays up as long as its left on the charger,
and I get a reasonable run time when using it - if it stops doing that
before they come round again (or the warranty expires) I'll probably open it
up and see what can be done.