Digital Camera Sensitive to a measely 25 mV??

[Watson A.Name \"Watt Sun]

I put a set of four Lenmar "No-Mem" NI-MH cells into my CP-990, and
turned it on. The battery indicator showed them as 1/4 charged, even
tho I had charged them just 6 weeks ago. I took 'em out and measured
them with the DMM, and they measured 1.297 V, all four within a few
thousandths of a volt. This is a reasonable value for cells that have
set for a month, and indicated they have discharged somewhat, but
_nowhere_near_ down to 1/4 charge. I do this regularly, and have done
it many, many times since I've had the camera without a problem. The
cells are always at least 3/4 charged.

So I took out a set of four Panasonic Ni-MH cells and measured them, and
they all four measured real close to 1.322V, only 25 mV more than the
No-mems. They had been sitting for a few weeks, too, maybe not as long
as the No-mems. I put them in, and the camera battery indicator said
they were fully charged(!)

So now, is this .025 V difference going to make that much difference? I
put the No-mems in a charger and I'll try them tomorrow when they've
charged for a dozen or so hours. I'll see then if they're having some
problem. Any thoughts? Maybe I should stop buying these Lenamar No-Mem
2000 MaH cells and pay an additional $4 or $5 a set for the Panasonic
Ni-MHs or Rayovacs or Energizer Bunnies (hey, it's easter!) On second
thought, since they were having a sale on Alkalines - four for a buck or
less, maybe I should just go back to the throwaways?? Thanks.

 

[Spehro Pefhany]

On Fri, 02 Apr 2004 07:36:43 -0800, the renowned "Watson A.Name \"Watt
Sun - the Dark Remover\"" <NOSPAM@dslextreme.com> wrote:

I put a set of four Lenmar "No-Mem" NI-MH cells into my CP-990, and
turned it on. The battery indicator showed them as 1/4 charged, even
tho I had charged them just 6 weeks ago. I took 'em out and measured
them with the DMM, and they measured 1.297 V, all four within a few
thousandths of a volt. This is a reasonable value for cells that have
set for a month, and indicated they have discharged somewhat, but
_nowhere_near_ down to 1/4 charge. I do this regularly, and have done
it many, many times since I've had the camera without a problem. The
cells are always at least 3/4 charged.

So I took out a set of four Panasonic Ni-MH cells and measured them, and
they all four measured real close to 1.322V, only 25 mV more than the
No-mems. They had been sitting for a few weeks, too, maybe not as long
as the No-mems. I put them in, and the camera battery indicator said
they were fully charged(!)

So now, is this .025 V difference going to make that much difference? I
put the No-mems in a charger and I'll try them tomorrow when they've
charged for a dozen or so hours. I'll see then if they're having some
problem. Any thoughts? Maybe I should stop buying these Lenamar No-Mem
2000 MaH cells and pay an additional $4 or $5 a set for the Panasonic
Ni-MHs or Rayovacs or Energizer Bunnies (hey, it's easter!) On second
thought, since they were having a sale on Alkalines - four for a buck or
less, maybe I should just go back to the throwaways?? Thanks.

Batteries don't really change much in open-circuit voltage during the
useful life, rather the internal resistance increases so you get less
voltage out *under load*. You need to measure the voltage under a
comparable load to what the camera draws to see how dead they are.

NiMH cells have a fairly high self-discharge rate.

Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

 

[repatch]

Measring the open circuit voltage of a NiMH cell isn't too useful, to
properly gauge capacity left you must measure under load.

"Watson A.Name "Watt Sun - the Dark Remover"" <NOSPAM@dslextreme.com> wrote
in message news:c4k17o$6i55n$1@hades.csu.net...

I put a set of four Lenmar "No-Mem" NI-MH cells into my CP-990, and
turned it on. The battery indicator showed them as 1/4 charged, even
tho I had charged them just 6 weeks ago. I took 'em out and measured
them with the DMM, and they measured 1.297 V, all four within a few
thousandths of a volt. This is a reasonable value for cells that have
set for a month, and indicated they have discharged somewhat, but
_nowhere_near_ down to 1/4 charge. I do this regularly, and have done
it many, many times since I've had the camera without a problem. The
cells are always at least 3/4 charged.

So I took out a set of four Panasonic Ni-MH cells and measured them, and
they all four measured real close to 1.322V, only 25 mV more than the
No-mems. They had been sitting for a few weeks, too, maybe not as long
as the No-mems. I put them in, and the camera battery indicator said
they were fully charged(!)

So now, is this .025 V difference going to make that much difference? I
put the No-mems in a charger and I'll try them tomorrow when they've
charged for a dozen or so hours. I'll see then if they're having some
problem. Any thoughts? Maybe I should stop buying these Lenamar No-Mem
2000 MaH cells and pay an additional $4 or $5 a set for the Panasonic
Ni-MHs or Rayovacs or Energizer Bunnies (hey, it's easter!) On second
thought, since they were having a sale on Alkalines - four for a buck or
less, maybe I should just go back to the throwaways?? Thanks.

 

[Martin]

"repatch" <repatch42@yahoo.com> wrote in message
newsbk0k1-fuj.ln1@host.domain...

Measring the open circuit voltage of a NiMH cell isn't too useful, to
properly gauge capacity left you must measure under load.

Here is a testing procedure for NiMH cells under load that I think I got
from someone one in this group. It's been very useful for sorting out
camera battery packs:

"---------------------------------------------------------------------------
Get a 0.3 - 0.5 ohm resistor and a pair of alligator clip leads.

Attach one clip to the resistor and the other to the red probe of
your VOM. Repeat for the other end of the resistor and black VOM
lead.

Put the VOM in voltage mode, 2V scale.

Put the red VOM lead on the plus terminal and the black on the minus.
If the voltage reads about 0.8V or better it's pretty sure you have a good
but
mostly discharged battery. Above 1.1V the battery still has useful charge.

Less than 0.8V: it may be a heavily discharged good battery or it may be
one
that has lost significant capacity.

If it's zero, remove one clip from a probe and measure the voltage again,
if its still zero this is probably a dead battery, but I'd put it on the
charger for ten minutes or so and see if it comes off zero, if not then
throw it away.

The totally dead ones are easy to find, its the ones that have lost capacity
that screw up the pack performance. Fully charge all batteries. Use them
as
a pack. When the device stops working due to low battery, check the
batteries
as above. Any battery that has 0.2-0.3 lower voltage than the rest when
tested under load has probably lost capacity and should be discarded from
the
pack.

Like a chain, the pack's performance is limited by the weakest battery.

----------------------------------------------------------------------------
----------"

I've found also that putting the apparently weak cells through one or more
conditioning cycles can in many cases bring them back to full capacity.

 

[Watson A.Name \"Watt Sun]

repatch wrote:

Measring the open circuit voltage of a NiMH cell isn't too useful, to
properly gauge capacity left you must measure under load.

But I had charged them Feb 14, about a month and a half ago. And all
four measured within a few mV of each other, implying that they were all
four charged the same. Yes, I realize that the OC voltage isn't a true
indicator of capacity, but I've measured other batteries like this with
positive results, the lower the voltage, the less charge they have left.
And yes, the camera is putting them under load and monitoring them for
their capacity, and one might surmise from that that the capacity,
according to the camera, is nearly exhausted.

"Watson A.Name "Watt Sun - the Dark Remover"" <NOSPAM@dslextreme.com> wrote
in message news:c4k17o$6i55n$1@hades.csu.net...

I put a set of four Lenmar "No-Mem" NI-MH cells into my CP-990, and
turned it on. The battery indicator showed them as 1/4 charged, even
tho I had charged them just 6 weeks ago. I took 'em out and measured
them with the DMM, and they measured 1.297 V, all four within a few
thousandths of a volt. This is a reasonable value for cells that have
set for a month, and indicated they have discharged somewhat, but
_nowhere_near_ down to 1/4 charge. I do this regularly, and have done
it many, many times since I've had the camera without a problem. The
cells are always at least 3/4 charged.

So I took out a set of four Panasonic Ni-MH cells and measured them, and
they all four measured real close to 1.322V, only 25 mV more than the
No-mems. They had been sitting for a few weeks, too, maybe not as long
as the No-mems. I put them in, and the camera battery indicator said
they were fully charged(!)

So now, is this .025 V difference going to make that much difference? I
put the No-mems in a charger and I'll try them tomorrow when they've
charged for a dozen or so hours. I'll see then if they're having some
problem. Any thoughts? Maybe I should stop buying these Lenamar No-Mem
2000 MaH cells and pay an additional $4 or $5 a set for the Panasonic
Ni-MHs or Rayovacs or Energizer Bunnies (hey, it's easter!) On second
thought, since they were having a sale on Alkalines - four for a buck or
less, maybe I should just go back to the throwaways?? Thanks.

 

[repatch]

NiMH batteries have horrible self discharge, I've seen batteries have
practically no charge after only a few months. Open circuit testing of NiMH
batteries is useless. I've seen one fully charged battery from one
manufacturer have a voltage almost the same as one almost fully discharged
from another. You MUST put them under load to make ANY sort of judgement as
to their remaining capacity. There is no other option.

Whether this has "worked" for you before or not is irrelevant.

"Watson A.Name "Watt Sun - the Dark Remover"" <NOSPAM@dslextreme.com> wrote
in message news:c4km37$6ibqa$1@hades.csu.net...

repatch wrote:

Measring the open circuit voltage of a NiMH cell isn't too useful, to
properly gauge capacity left you must measure under load.

But I had charged them Feb 14, about a month and a half ago. And all
four measured within a few mV of each other, implying that they were all
four charged the same. Yes, I realize that the OC voltage isn't a true
indicator of capacity, but I've measured other batteries like this with
positive results, the lower the voltage, the less charge they have left.
And yes, the camera is putting them under load and monitoring them for
their capacity, and one might surmise from that that the capacity,
according to the camera, is nearly exhausted.


"Watson A.Name "Watt Sun - the Dark Remover"" <NOSPAM@dslextreme.com
wrote
in message news:c4k17o$6i55n$1@hades.csu.net...

I put a set of four Lenmar "No-Mem" NI-MH cells into my CP-990, and
turned it on. The battery indicator showed them as 1/4 charged, even
tho I had charged them just 6 weeks ago. I took 'em out and measured
them with the DMM, and they measured 1.297 V, all four within a few
thousandths of a volt. This is a reasonable value for cells that have
set for a month, and indicated they have discharged somewhat, but
_nowhere_near_ down to 1/4 charge. I do this regularly, and have done
it many, many times since I've had the camera without a problem. The
cells are always at least 3/4 charged.

So I took out a set of four Panasonic Ni-MH cells and measured them, and
they all four measured real close to 1.322V, only 25 mV more than the
No-mems. They had been sitting for a few weeks, too, maybe not as long
as the No-mems. I put them in, and the camera battery indicator said
they were fully charged(!)

So now, is this .025 V difference going to make that much difference? I
put the No-mems in a charger and I'll try them tomorrow when they've
charged for a dozen or so hours. I'll see then if they're having some
problem. Any thoughts? Maybe I should stop buying these Lenamar No-Mem
2000 MaH cells and pay an additional $4 or $5 a set for the Panasonic
Ni-MHs or Rayovacs or Energizer Bunnies (hey, it's easter!) On second
thought, since they were having a sale on Alkalines - four for a buck or
less, maybe I should just go back to the throwaways?? Thanks.

 

[Jamie]

check the volts with a load on it.


Watson A.Name "Watt Sun - the Dark Remover" wrote:

I put a set of four Lenmar "No-Mem" NI-MH cells into my CP-990, and
turned it on. The battery indicator showed them as 1/4 charged, even
tho I had charged them just 6 weeks ago. I took 'em out and measured
them with the DMM, and they measured 1.297 V, all four within a few
thousandths of a volt. This is a reasonable value for cells that have
set for a month, and indicated they have discharged somewhat, but
_nowhere_near_ down to 1/4 charge. I do this regularly, and have done
it many, many times since I've had the camera without a problem. The
cells are always at least 3/4 charged.

So I took out a set of four Panasonic Ni-MH cells and measured them, and
they all four measured real close to 1.322V, only 25 mV more than the
No-mems. They had been sitting for a few weeks, too, maybe not as long
as the No-mems. I put them in, and the camera battery indicator said
they were fully charged(!)

So now, is this .025 V difference going to make that much difference? I
put the No-mems in a charger and I'll try them tomorrow when they've
charged for a dozen or so hours. I'll see then if they're having some
problem. Any thoughts? Maybe I should stop buying these Lenamar No-Mem
2000 MaH cells and pay an additional $4 or $5 a set for the Panasonic
Ni-MHs or Rayovacs or Energizer Bunnies (hey, it's easter!) On second
thought, since they were having a sale on Alkalines - four for a buck or
less, maybe I should just go back to the throwaways?? Thanks.

 

[Tim Williams]

Hey Watson, you double-posted to ABPR.

Hey Watson, you double-posted to ABPR.

Hey Watson, you double-posted to ABPR.

Hey Watson, you double-posted to ABPR.

Tim

--
"I have misplaced my pants." - Homer Simpson | Electronics,
- - - - - - - - - - - - - - - - - - - - - - --+ Metalcasting
and Games: http://webpages.charter.net/dawill/tmoranwms

"Watson A.Name "Watt Sun - the Dark Remover"" <NOSPAM@dslextreme.com> wrote
in message news:c4k17o$6i55n$1@hades.csu.net...

thought, since they were having a sale on Alkalines - four for a buck or
less, maybe I should just go back to the throwaways?? Thanks.

 

[Watson A.Name - \"Watt Su]

"Tim Williams" <tmoranwms@charter.net> wrote in message
news:106un5g1j2d8ea@corp.supernews.com...

Hey Watson, you double-posted to ABPR.

Hey Watson, you double-posted to ABPR.

Hey Watson, you double-posted to ABPR.

Hey Watson, you double-posted to ABPR.

Tim

Weird. That's Outhouse Express for ya!

--

"Watson A.Name "Watt Sun - the Dark Remover"" <NOSPAM@dslextreme.com
wrote
in message news:c4k17o$6i55n$1@hades.csu.net...
thought, since they were having a sale on Alkalines - four for a
buck or
less, maybe I should just go back to the throwaways?? Thanks.