NiMh voltage?

In article , J. Clarke
wrote:

Had the same issue with my wife's old Nikon P&S. Never could reconcile it
- but we finally gave up and tried Lithium (non-rechargeable) batties and
they lasted a LONG time. Convenience vs cost.

Be careful with Lithium. There are 1.5v AA batteries with lithium and
there are others that are 3.7 volt. Make sure you're getting the right
kind.

consumer lithium aa batteries are not rechargeable and 1.6v. there is
no risk.

rechargeable lithium ion batteries are a different chemistry and 3.7v.
they are intentionally a different size so that you *can't* screw it
up, and they also come in a custom size pack, requiring a custom
charger.

there are aa sized lithium ion aa size cells (if you know where to find
them, and it's not walmart), but they're slightly shorter and won't do
anything in a device designed for standard aa batteries. they're
usually sold with tabs to solder into a battery pack.

On 10/22/2013 5:56 PM, nospam wrote:
In article , J. Clarke
wrote:

Had the same issue with my wife's old Nikon P&S. Never could reconcile it
- but we finally gave up and tried Lithium (non-rechargeable) batties and
they lasted a LONG time. Convenience vs cost.

Be careful with Lithium. There are 1.5v AA batteries with lithium and
there are others that are 3.7 volt. Make sure you're getting the right
kind.

consumer lithium aa batteries are not rechargeable and 1.6v. there is
no risk.

rechargeable lithium ion batteries are a different chemistry and 3.7v.
they are intentionally a different size so that you *can't* screw it
up, and they also come in a custom size pack, requiring a custom
charger.

there are aa sized lithium ion aa size cells (if you know where to find
them, and it's not walmart), but they're slightly shorter and won't do
anything in a device designed for standard aa batteries. they're
usually sold with tabs to solder into a battery pack.


Yup!

--
PeterN

On 22/10/2013 15:26, bugbear wrote:
I have a (old) Canon A630 camera.

I can get very few shots/use out of a freshly charged set of
NiMh AA batteries, and yet when I put them in a halogen
bulb torch, the torch will run for hours.

It is a common problem with some of the older cameras. They have logic
to shutdown the camera when the terminal voltage of the presumed primary
cell battery pack drops below a certain fixed value under load.

There is also a possibility that you have a single weak cell developed
in a pack and that will spoil the entire sets capacity.

You can't tell which is which unless you can load them with about 500mA
and measure the terminal voltage (typical current draw for an older but
not massively old camera). Unloaded voltage is no guide to the fitness
of a cell or otherwise - you need a load based battery tester.

I assume it's related to voltage, not Ah capacity.

Do brands/models of NiMh battery vary in voltage,
and (if so) can anyone recommend a high(er) voltage type?

BugBear

Sadly no. They have lower internal resistance than primary types, but
although when freshly charged they have terminal voltage of ~1.4v it
quickly falls below the older cameras panic and shutdown threshold of
~1.3v. Even the primary alkaline cells are not giving all they could and
such batteries will have a fair residual capacity left even when the
camera rejects them. More modern cameras tend to have their "give up"
threshold set to below the 1.2v discharge plateau of rechargables, but
the early ones didn't. This graph shows the battery discharge
characterisitics for eneloop(blue), NiMH(black) and alkaline(pink)

http://s3.media.squarespace.com/prod...ve-540x380.gif

A lot of them now use other battery technologies in custom packs.

The advantage of AA cells is you can buy them most places.

I keep my once used AA cells for use in other low current drain
applications where terminal voltage is non-critical. I do use and get
decent life out of my NiMH in a Pentax istD but I have matched the sets
and periodically weed out failing cells. I carry a set of alkaline
spares too as high self discharge is a problem with most NiMH.

--
Regards,
Martin Brown

On Tue, 22 Oct 2013 15:57:38 -0400, (Hactar)
wrote:

In article ,
bugbear wrote:
I have a (old) Canon A630 camera.

I can get very few shots/use out of a freshly charged set of
NiMh AA batteries, and yet when I put them in a halogen
bulb torch, the torch will run for hours.

Incandescent bulbs are more tolerant of lower voltages than are
electronics.

I assume it's related to voltage, not Ah capacity.

Nominal alkaline or C-Zn batteries make 1.5v, nominal NiMH batteries make
1.2v. My previous labelmaker took 5 AAs, probably on the assumption that
the user would install NiMH batteries (correct in my case). Presumably
with alk/C-Zn you could short out one slot and it'd work fine.
(5*1.2v = 6v = 4*1.5v)

Maybe the camera's threshold for "he's dead, Jim" is at such a level that
would indicate a really dead alk/C-Zn, but only a slightly used NiMH.

Do brands/models of NiMh battery vary in voltage,

Not much. The chemistry determines the voltage.

and (if so) can anyone recommend a high(er) voltage type?

You can get one with a lower internal resistance. It'll droop less under
current drain. No, I don't know different brands' characteristics.


The internal resistance issue is the explanation I was given when my
camera refused to work and I was on the point of throwing it out. I
kept buying higher rating Energiser rechargeables only for them to
fail to get the camera working. Sanyo Eneloops were then recommended
because of their low internal resistance and the camera has worked
perfectly for the past 3 years. I now rarely use anything else.


--
AnthonyL

Le 22/10/13 16:26, bugbear a écrit :
I have a (old) Canon A630 camera.

I can get very few shots/use out of a freshly charged set of
NiMh AA batteries, and yet when I put them in a halogen
bulb torch, the torch will run for hours.

I assume it's related to voltage, not Ah capacity.

Do brands/models of NiMh battery vary in voltage,
and (if so) can anyone recommend a high(er) voltage type?

NiMH output voltage is lower than of one-use batteries.
And it is not enough for some cameras.

My F4s cannot use reusable batteries, just alkalines.
So you have to look at the documentation.

Some new Nimh have higher energy storage, but not higher voltage.
Those are a good recommandation for feeding flashes.

Noëlle Adam

J. Clarke wrote:
In article ,


This is a known problem with the Powershot A630. If you google "A630
NIMH" you'll find numerous reports of the behavior you describe.

The only discussion I could find that actually reported a solution was
this one:

http://www.candlepowerforums.com/vb/...028-I-think-I-
fried-my-Canon-Powershot-A630-**FIXED-thanks-Nitroz!!!**

In summary, the solution was to clean all the contacts in the battery
compartment with a new pencil eraser. If that doesn't work try some
super fine sandpaper (the kind you get at an auto parts store).

I'll try that. Since I have the CHDK software, which can report voltage
to 4 sig figs, I will also do a before/after comparison.

Thanks for the info.

BugBear

On 24/10/2013 11:31, Whisky-dave wrote:
On Thursday, 24 October 2013 11:12:03 UTC+1, bugbear wrote:
J. Clarke wrote:

In article ,





This is a known problem with the Powershot A630. If you google "A630

NIMH" you'll find numerous reports of the behavior you describe.



The only discussion I could find that actually reported a solution was

this one:



http://www.candlepowerforums.com/vb/...028-I-think-I-

fried-my-Canon-Powershot-A630-**FIXED-thanks-Nitroz!!!**
In summary, the solution was to clean all the contacts in the battery
compartment with a new pencil eraser. If that doesn't work try some
super fine sandpaper (the kind you get at an auto parts store).

I'll try that. Since I have the CHDK software, which can report voltage

to 4 sig figs, I will also do a before/after comparison.

Unless they are visibly tarnished it won't make a blind bit of
difference. What you are seeing is an exaggerated version of the
discharge capacity curve because NiMH starts from a lower voltage and
the on load cutoff for the A630 is set a bit on the high side.

You may be barking up the wrong tree there, measuring voltage to such a degree is pretty pointless. As, if an LED or display attempts to turn on then that requires a particular current from the batteries if the charge or rather the amount of energy in the battery is too little then lighting that LED will lower the voltage of the battery perhaps significantly enough that the voltage has fallen to below minium for the rest of the circuit to function within designed specs.

The things that draw serious current are realtime display, running in
video mode and charging xenon flash in increasing order of current draw
(usually). Not sure how bad LED flash recharges are.

I have had my Canon Ixus 100S shutdown on me from overheating when doing
sustained video with it and that is with Li-ion cells. Convinced me that
I needed to get a proper digital video camera. Bye bye Hi8.


--
Regards,
Martin Brown

? "Martin Brown" ?????? ??? ??????
...
On 24/10/2013 11:31, Whisky-dave wrote:
On Thursday, 24 October 2013 11:12:03 UTC+1, bugbear wrote:
J. Clarke wrote:

In article ,





This is a known problem with the Powershot A630. If you google "A630

NIMH" you'll find numerous reports of the behavior you describe.



The only discussion I could find that actually reported a solution was

this one:



http://www.candlepowerforums.com/vb/...028-I-think-I-

fried-my-Canon-Powershot-A630-**FIXED-thanks-Nitroz!!!**
In summary, the solution was to clean all the contacts in the battery
compartment with a new pencil eraser. If that doesn't work try some
super fine sandpaper (the kind you get at an auto parts store).

I'll try that. Since I have the CHDK software, which can report voltage

to 4 sig figs, I will also do a before/after comparison.

Unless they are visibly tarnished it won't make a blind bit of difference.
What you are seeing is an exaggerated version of the discharge capacity
curve because NiMH starts from a lower voltage and the on load cutoff for
the A630 is set a bit on the high side.

You may be barking up the wrong tree there, measuring voltage to such a
degree is pretty pointless. As, if an LED or display attempts to turn on
then that requires a particular current from the batteries if the charge
or rather the amount of energy in the battery is too little then lighting
that LED will lower the voltage of the battery perhaps significantly
enough that the voltage has fallen to below minium for the rest of the
circuit to function within designed specs.

The things that draw serious current are realtime display, running in
video mode and charging xenon flash in increasing order of current draw
(usually). Not sure how bad LED flash recharges are.

I have had my Canon Ixus 100S shutdown on me from overheating when doing
sustained video with it and that is with Li-ion cells. Convinced me that I
needed to get a proper digital video camera. Bye bye Hi8.

agreed. I have the Sony DCR-SX15, cost I think 180 euros and works with an
SD card. With a 4 GB one you can record up to an hour, continuously, with
the stock battery. It's SD, though. It is very light and compact, goes
without saying. It also takes sony's proprietary memory sticks, too. comes
with simple editing software, it lets me make NTSC dvds for my canadian
aunt.



--
Tzortzakakis Dimitris
hordad AT otenet DOT gr

"David Taylor" wrote in message
...
On 22/10/2013 15:26, bugbear wrote:
I have a (old) Canon A630 camera.

I can get very few shots/use out of a freshly charged set of
NiMh AA batteries, and yet when I put them in a halogen
bulb torch, the torch will run for hours.

I assume it's related to voltage, not Ah capacity.

Do brands/models of NiMh battery vary in voltage,
and (if so) can anyone recommend a high(er) voltage type?

BugBear

It's possible that the camera has a higher current drain, or has developed
a fault causing same. You could try with a fresh set of batteries, or
even non-rechargeables. How old are the NiMH cells - they don't last for
ever. I bought fresh Sanyo eneloops after 3-4 years use. The voltage is
likely dependent on the chemistry, and unlikely to vary a lot between
brands.


I have--on occasion--used a Canon A560 camera, which uses two AA size
batteries.

With NiMH, after about four or five photos using automatic flash, it is
already showing Low Battery. I get about ten to fifteen more photos maximum
and then I have to change batteries. This is with Lenmar 2000 mAh NiMH
batteries. I also have some Lenmar 2400 mAh NiMH batteries that give a
little longer battery usage.

Alkaline batteries actually give even more photos that NiMH. Maybe I get ten
or so photos before Low Battery and about twenty five to thirty more photos
before I have to change batteries.

I haven't tried those Lithium type AA batteries, though they are marketed as
being suitable for higher drain devices.

I think it's just that the LCD screen draws a lot of current. Also, I think
Canon may have made the Low Battery indicator too soon in general. This
battery drain isn't nearly as noticable when using just the optical
viewfinder with the LCD screen off.

In article ,
OSPAM says...

"David Taylor" wrote in message
...
On 22/10/2013 15:26, bugbear wrote:
I have a (old) Canon A630 camera.

I can get very few shots/use out of a freshly charged set of
NiMh AA batteries, and yet when I put them in a halogen
bulb torch, the torch will run for hours.

I assume it's related to voltage, not Ah capacity.

Do brands/models of NiMh battery vary in voltage,
and (if so) can anyone recommend a high(er) voltage type?

BugBear

It's possible that the camera has a higher current drain, or has developed
a fault causing same. You could try with a fresh set of batteries, or
even non-rechargeables. How old are the NiMH cells - they don't last for
ever. I bought fresh Sanyo eneloops after 3-4 years use. The voltage is
likely dependent on the chemistry, and unlikely to vary a lot between
brands.


I have--on occasion--used a Canon A560 camera, which uses two AA size
batteries.

With NiMH, after about four or five photos using automatic flash, it is
already showing Low Battery. I get about ten to fifteen more photos maximum
and then I have to change batteries. This is with Lenmar 2000 mAh NiMH
batteries. I also have some Lenmar 2400 mAh NiMH batteries that give a
little longer battery usage.

Alkaline batteries actually give even more photos that NiMH. Maybe I get ten
or so photos before Low Battery and about twenty five to thirty more photos
before I have to change batteries.

I haven't tried those Lithium type AA batteries, though they are marketed as
being suitable for higher drain devices.

I think it's just that the LCD screen draws a lot of current. Also, I think
Canon may have made the Low Battery indicator too soon in general. This
battery drain isn't nearly as noticable when using just the optical
viewfinder with the LCD screen off.

If you google "A560 NiMH Problem" you'll find numerous reports of what
you are seeing. Again it seems to be a mechanical issue with the
battery contacts. Some have reported succcess by cleaning them with a
pencil eraser (always worth a try--if it works it's a cheap fix, if it
doesn't work you haven't spent anything but a minute or so of your
time). Others have reported success from shimming the contacts on the
door in various ways--using flat wooden toothpicks under them or pieces
of cardboard or thin foam for example.