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A Battery Warning query

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August 23, 2005 12:39:07 PM

Archived from groups: rec.photo.digital (More info?)

I have recently purchased a vertical hold "grip" for my Canon Élan II
camera. It also can hold AA batteries to replace the regular 6-V Lithium
normal grip battery. It came with a warning to use Alkaline batteries only,
NOT Lithium AA cells as camera damage might result. How/why?

Thanks,
Larry

More about : battery warning query

Anonymous
August 23, 2005 5:05:21 PM

Archived from groups: rec.photo.digital (More info?)

Larry wrote:
>I have recently purchased a vertical hold "grip" for my Canon Élan II
> camera. It also can hold AA batteries to replace the regular 6-V
> Lithium normal grip battery. It came with a warning to use Alkaline
> batteries only, NOT Lithium AA cells as camera damage might result.
> How/why?
> Thanks,
> Larry

I can only guess, but I would guess the lithium batteries may be able to
deliver a higher voltage-amps and that could overheat a part in the camera.


--
Joseph Meehan

Dia duit
Anonymous
August 23, 2005 6:34:29 PM

Archived from groups: rec.photo.digital (More info?)

"Joseph Meehan" <sligojoe_Spamno@hotmail.com> wrote in message
news:laFOe.9535$ja7.3481@tornado.ohiordc.rr.com...
> Larry wrote:
>>I have recently purchased a vertical hold "grip" for my Canon Élan II
>> camera. It also can hold AA batteries to replace the regular 6-V
>> Lithium normal grip battery. It came with a warning to use Alkaline
>> batteries only, NOT Lithium AA cells as camera damage might result.
>> How/why?
>> Thanks,
>> Larry
>
> I can only guess, but I would guess the lithium batteries may be able
> to deliver a higher voltage-amps and that could overheat a part in the
> camera.
>
>
> --
> Joseph Meehan
>
> Dia duit
Same warning with my canon A40, but can't find anything in my A95 manual.
Mute point since NiMH are the obvious choice. I agree must be a voltage
thing.
Dave Cohen
Related resources
Anonymous
August 23, 2005 11:57:27 PM

Archived from groups: rec.photo.digital (More info?)

Larry wrote:

> I have recently purchased a vertical hold "grip" for my Canon Élan II
> camera. It also can hold AA batteries to replace the regular 6-V Lithium
> normal grip battery. It came with a warning to use Alkaline batteries
> only, NOT Lithium AA cells as camera damage might result. How/why?
>
> Thanks,
> Larry
An earlier discussion of Lithium AA cells regarding film cameras a few
years ago revealed that, due to lower internal resistance, Li cells can
deliver a higher current flow (same voltage) which can heat up and
destroy some sensitive electronic components.
IMHO, Li AA cells have almost no place in photography; they are 10x more
expensive than alkalines and give only 2-3x the number of pictures per cell.

Morton
Anonymous
August 24, 2005 12:37:55 AM

Archived from groups: rec.photo.digital (More info?)

On Tue, 23 Aug 2005 19:57:27 -0400, Morton Linder wrote:

> An earlier discussion of Lithium AA cells regarding film cameras a few
> years ago revealed that, due to lower internal resistance, Li cells can
> deliver a higher current flow (same voltage) which can heat up and
> destroy some sensitive electronic components.

Absolutely not true. At a given voltage (under load), the camera
will draw the same current, whether the source is alkaline or
lithium, whether they are AAA, AA, C or D cells. Under load, the
voltage delivered by fresh alkaline batteries is not substantially
higher than that of lithium batteries, but in any case the high
current draw isn't continuous. The components that might get
excessively warm or hot would be batteries, flash tubes and the
power supply used to charge the flash's capacitors. Operating
cameras in high temperatures would probably be worse, but except for
the usual fine print disclaimers at the back of manuals where
operating environment parameters are listed, manufacturers rarely go
out of their way to warn about the effects of heat.


> IMHO, Li AA cells have almost no place in photography; they are 10x more
> expensive than alkalines and give only 2-3x the number of pictures per cell.

They do have a place in photography. With modern cameras that
don't consume huge currents, they might provide only 2 to 3 times
longer operating life. But with older, power hungry cameras they
can provide more than 10x the life of alkalines. They're also the
only battery type available for cameras that don't suffer tremendous
performance loss in very cold weather. They're also about 10x more
expensive than alkalines only for those that shop carefully. With
the prices most people pay for alkaline batteries, they're more like
3 to 6 times more expensive, not 10x.

Another advantage I haven't heard mentioned concerns battery
leakage. I don't know if lithium batteries can leak, and if they do
how corrosive it might be. What I do know is that any camera or
other electrical device that uses alkalines is checked by me at
least several times/year for leakage. But I have a very old, rarely
used Stylus (film camera) that is powered by a lithium battery. It
still provides lots of power and has been in the camera so long I no
longer remember when it was last changed. At least 10 years ago.
And I don't check the battery in that one more frequently than every
4 or 5 years or so. :) 
Anonymous
August 24, 2005 1:18:49 AM

Archived from groups: rec.photo.digital (More info?)

Hi Larry,

My FinePix A203/A303 manual says "Do not to use AA-size manganese, lithium,
or Ni-Cd batteries in your FinePix A203/A303 because the heat generated by
the batteries could damage the camera or cause malfuctions."

Ken

"Larry" <laocmo@copper.net> wrote in message
news:430b194a$1_5@newsfeed.slurp.net...
> I have recently purchased a vertical hold "grip" for my Canon Élan II
> camera. It also can hold AA batteries to replace the regular 6-V Lithium
> normal grip battery. It came with a warning to use Alkaline batteries
only,
> NOT Lithium AA cells as camera damage might result. How/why?
>
> Thanks,
> Larry
>
Anonymous
August 24, 2005 2:53:06 AM

Archived from groups: rec.photo.digital (More info?)

There is no reason why you should not be able to use Lithium cells. The
voltage is the same as Alkalines just better extreme temp. performance,
different discharge characteristics and a 15 year shelf life.

The 2CR5 or 223 that you are replacing is already a Lithium pack made up of
lithium cells.

LiIon's if you could get them in that size would be bad as they are
nominally 3.6v per cell.

However as a previous poster said, the better choice would be to use NiMh
rechargeables, four in the camera, four in the charger and 4 alkalines as
backup.

Joel

"Larry" <laocmo@copper.net> wrote in message
news:430b194a$1_5@newsfeed.slurp.net...
> I have recently purchased a vertical hold "grip" for my Canon Élan II
> camera. It also can hold AA batteries to replace the regular 6-V Lithium
> normal grip battery. It came with a warning to use Alkaline batteries
only,
> NOT Lithium AA cells as camera damage might result. How/why?
>
> Thanks,
> Larry
>
Anonymous
August 24, 2005 2:53:07 AM

Archived from groups: rec.photo.digital (More info?)

Joel Dorfan wrote:
> There is no reason why you should not be able to use Lithium cells.
> The voltage is the same as Alkalines

Nominal or operating voltage. I suspect the Lithiums go out of spec
when in use.

> just better extreme temp.
> performance, different discharge characteristics and a 15 year shelf
> life.
>
> The 2CR5 or 223 that you are replacing is already a Lithium pack made
> up of lithium cells.
>
> LiIon's if you could get them in that size would be bad as they are
> nominally 3.6v per cell.
>
> However as a previous poster said, the better choice would be to use
> NiMh rechargeables, four in the camera, four in the charger and 4
> alkalines as backup.
>
> Joel
>
> "Larry" <laocmo@copper.net> wrote in message
> news:430b194a$1_5@newsfeed.slurp.net...
>> I have recently purchased a vertical hold "grip" for my Canon Élan II
>> camera. It also can hold AA batteries to replace the regular 6-V
>> Lithium normal grip battery. It came with a warning to use Alkaline
>> batteries only, NOT Lithium AA cells as camera damage might result.
>> How/why?
>>
>> Thanks,
>> Larry

--
Joseph Meehan

Dia duit
Anonymous
August 24, 2005 2:53:08 AM

Archived from groups: rec.photo.digital (More info?)

On Tue, 23 Aug 2005 22:24:02 GMT, Joseph Meehan wrote:

>> There is no reason why you should not be able to use Lithium cells.
>> The voltage is the same as Alkalines
>
> Nominal or operating voltage. I suspect the Lithiums go out of spec
> when in use.

Is the problem really with lithium AAs? I thought that there has
long been a specially formulated high performance alkaline battery
whose voltage was about 10% higher than standard alkalines. Maybe
they're the ones with the "Titanium" description on the package.
Anonymous
August 24, 2005 3:16:43 AM

Archived from groups: rec.photo.digital (More info?)

"ASAAR" <caught@22.com> wrote in message
news:4t8ng1h6anpuo8pvhk02cmi921cbpcf7fq@4ax.com...
> On Tue, 23 Aug 2005 22:24:02 GMT, Joseph Meehan wrote:
>
>>> There is no reason why you should not be able to use Lithium cells.
>>> The voltage is the same as Alkalines
>>
>> Nominal or operating voltage. I suspect the Lithiums go out of spec
>> when in use.
>
> Is the problem really with lithium AAs? I thought that there has
> long been a specially formulated high performance alkaline battery
> whose voltage was about 10% higher than standard alkalines. Maybe
> they're the ones with the "Titanium" description on the package.
>
Not quite true to say lithium and alkaline would display same working
voltage. Open circuit voltage may be same, but higher internal resistance of
the alkaline would present less than 6 volts to camera when drawing current.
Dave Cohen
Anonymous
August 24, 2005 3:16:44 AM

Archived from groups: rec.photo.digital (More info?)

On Tue, 23 Aug 2005 23:16:43 GMT, Dave Cohen wrote:

>> Is the problem really with lithium AAs? I thought that there has
>> long been a specially formulated high performance alkaline battery
>> whose voltage was about 10% higher than standard alkalines. Maybe
>> they're the ones with the "Titanium" description on the package.
>>
> Not quite true to say lithium and alkaline would display same working
> voltage. Open circuit voltage may be same, but higher internal resistance of
> the alkaline would present less than 6 volts to camera when drawing current.

Where did you see me say that? What I said has nothing to do with
a working voltage. It's true that in a digital camera the working
voltage of alkalines will dip lower while the camera is busy,
zooming the lens, capturing the image, recharging the flash, etc.
Lithium's would also show a voltage drop under those conditions.
But what might be bad for the camera occurs when the current draw is
minimal, with the camera on, display off, etc. Then the "working
voltage" of both battery types would be nearest to their "no load"
voltages and differences would be minimal. But if batteries that
have voltages measurably higher than the approx. 1.5v of standard
alkalines are used, they could present problems. If they're used
for a while in a radio or tape player so that their load under low
current draws results in a voltage below 1.5v, they should then be
safe to use in the camera. There have been some cameras (such as in
one older model reported by a Kodak user) where the manual stated
that only NiMH batteries should be used, as standard alkalines might
cause damage.
Anonymous
August 24, 2005 4:52:56 AM

Archived from groups: rec.photo.digital (More info?)

ASAAR wrote:
> On Tue, 23 Aug 2005 19:57:27 -0400, Morton Linder wrote:
>
>> An earlier discussion of Lithium AA cells regarding film cameras a
>> few years ago revealed that, due to lower internal resistance, Li
>> cells can deliver a higher current flow (same voltage) which can
>> heat up and
>> destroy some sensitive electronic components.
>
> Absolutely not true. At a given voltage (under load), the camera
> will draw the same current, whether the source is alkaline or
> lithium, whether they are AAA, AA, C or D cells.

But the issue is it appears that Lithium batteries deliver a higher
voltage under load, and therefore have the potential to deliver more
current.

> Under load, the
> voltage delivered by fresh alkaline batteries is not substantially
> higher than that of lithium batteries, but in any case the high
> current draw isn't continuous. The components that might get
> excessively warm or hot would be batteries, flash tubes and the
> power supply used to charge the flash's capacitors. Operating
> cameras in high temperatures would probably be worse, but except for
> the usual fine print disclaimers at the back of manuals where
> operating environment parameters are listed, manufacturers rarely go
> out of their way to warn about the effects of heat.

In general I would agree but the OP was asking about a specific camera
with a warning.

>
>
>> IMHO, Li AA cells have almost no place in photography; they are 10x
>> more expensive than alkalines and give only 2-3x the number of
>> pictures per cell.
>
> They do have a place in photography. With modern cameras that
> don't consume huge currents, they might provide only 2 to 3 times
> longer operating life. But with older, power hungry cameras they
> can provide more than 10x the life of alkalines. They're also the
> only battery type available for cameras that don't suffer tremendous
> performance loss in very cold weather. They're also about 10x more
> expensive than alkalines only for those that shop carefully. With
> the prices most people pay for alkaline batteries, they're more like
> 3 to 6 times more expensive, not 10x.
>
> Another advantage I haven't heard mentioned concerns battery
> leakage. I don't know if lithium batteries can leak, and if they do
> how corrosive it might be. What I do know is that any camera or
> other electrical device that uses alkalines is checked by me at
> least several times/year for leakage. But I have a very old, rarely
> used Stylus (film camera) that is powered by a lithium battery. It
> still provides lots of power and has been in the camera so long I no
> longer remember when it was last changed. At least 10 years ago.
> And I don't check the battery in that one more frequently than every
> 4 or 5 years or so. :) 

--
Joseph Meehan

Dia duit
Anonymous
August 24, 2005 5:59:54 AM

Archived from groups: rec.photo.digital (More info?)

"Joel Dorfan" <bdorfan@MAPSicon.co.za> writes:
>There is no reason why you should not be able to use Lithium cells. The
>voltage is the same as Alkalines just better extreme temp. performance,
>different discharge characteristics and a 15 year shelf life.

No, the voltage is higher as well. It's something like 1.65 V when new.
Alkalines are more like 1.5 V, and that drops under load. If a device
is designed with "fresh alkalines" as its maximum voltage reference, it
could conceivably be damaged by using lithium AAs.

>The 2CR5 or 223 that you are replacing is already a Lithium pack made up of
>lithium cells.

Those are completely different lithium chemistry, with 3 V per cell.
Two 3V cells give about 6 V, just like 4 AA alkalines, and less than 4
AA lithiums at about 6.6 V.

>LiIon's if you could get them in that size would be bad as they are
>nominally 3.6v per cell.

LiIon is a *third* different "lithium" chemistry, not related to the two
previously mentioned. They're about 3.7 V nominal, but up to 4.2 V at
end of a full charge.

>However as a previous poster said, the better choice would be to use NiMh
>rechargeables, four in the camera, four in the charger and 4 alkalines as
>backup.

Good suggestion.

Dave
Anonymous
August 24, 2005 11:58:36 AM

Archived from groups: rec.photo.digital (More info?)

"Joseph Meehan" <sligojoe_Spamno@hotmail.com> wrote in message
news:IxPOe.43918$gB.26562@tornado.ohiordc.rr.com...
> ASAAR wrote:
>> On Tue, 23 Aug 2005 19:57:27 -0400, Morton Linder wrote:
>>
>>> An earlier discussion of Lithium AA cells regarding film cameras a
>>> few years ago revealed that, due to lower internal resistance, Li
>>> cells can deliver a higher current flow (same voltage) which can
>>> heat up and
>>> destroy some sensitive electronic components.
>>
>> Absolutely not true. At a given voltage (under load), the camera
>> will draw the same current, whether the source is alkaline or
>> lithium, whether they are AAA, AA, C or D cells.
>
> But the issue is it appears that Lithium batteries deliver a higher
> voltage under load, and therefore have the potential to deliver more
> current.

And therefore the higher voltage should equate to lower current!
August 24, 2005 2:29:20 PM

Archived from groups: rec.photo.digital (More info?)

In article <IxPOe.43918$gB.26562@tornado.ohiordc.rr.com>, Joseph Meehan
<sligojoe_Spamno@hotmail.com> writes
> But the issue is it appears that Lithium batteries deliver a higher
>voltage under load, and therefore have the potential to deliver more
>current.

The camera will use a regulator(s) to supply the various circuits inside
it with power. If it is a simple linear reg. then it will run warmer
with a higher battery voltage because it has to drop more volts, the
current is unaltered although it is taking higher power from the
battery. If it is a switching reg. then for higher a battery voltage
the input current will reduce thus maintaining a consistent power
dissipation in the reg. and power consumption from the battery. Since
switching regs are much more efficient and can operate where the input
is less than the required output (or both +ve & -ve lines are required)
they are preferentially used.
--
Ian G8ILZ
Anonymous
August 24, 2005 3:38:49 PM

Archived from groups: rec.photo.digital (More info?)

Pete D wrote:
> "Joseph Meehan" <sligojoe_Spamno@hotmail.com> wrote in message
> news:IxPOe.43918$gB.26562@tornado.ohiordc.rr.com...
>> ASAAR wrote:
>>> On Tue, 23 Aug 2005 19:57:27 -0400, Morton Linder wrote:
>>>
>>>> An earlier discussion of Lithium AA cells regarding film cameras a
>>>> few years ago revealed that, due to lower internal resistance, Li
>>>> cells can deliver a higher current flow (same voltage) which can
>>>> heat up and
>>>> destroy some sensitive electronic components.
>>>
>>> Absolutely not true. At a given voltage (under load), the camera
>>> will draw the same current, whether the source is alkaline or
>>> lithium, whether they are AAA, AA, C or D cells.
>>
>> But the issue is it appears that Lithium batteries deliver a
>> higher voltage under load, and therefore have the potential to
>> deliver more current.
>
> And therefore the higher voltage should equate to lower current!

It would IF there was something to limit it, but there may not be
anything limiting it.


--
Joseph Meehan

Dia duit
Anonymous
August 24, 2005 4:28:07 PM

Archived from groups: rec.photo.digital (More info?)

Ken Hartlen <khartlen@interlog.com> wrote:
|| Hi Larry,
||
|| My FinePix A203/A303 manual says "Do not to use AA-size
|| manganese, lithium, or Ni-Cd batteries in your FinePix
|| A203/A303 because the heat generated by the batteries could
|| damage the camera or cause malfuctions."
||

Same statement is in the manual for my old FinePix 4700.

--
--
"When you're arguing with a fool, make sure he isn't doing the
same thing." -- Unknown
Anonymous
August 24, 2005 8:09:26 PM

Archived from groups: rec.photo.digital (More info?)

"Pete D" <no@email.com> writes:

>> But the issue is it appears that Lithium batteries deliver a higher
>> voltage under load, and therefore have the potential to deliver more
>> current.

>And therefore the higher voltage should equate to lower current!

Why? This depends entirely on the characteristics of the load.

If the battery is feeding a switching voltage regulator, increasing the
input voltage reduces the input current while the power remains
approximately the same. This might be true for the power used to drive
the electronics in the camera.

If the battery is powering a constant-current load, then the current
remains about the same while voltage rises.

And if the battery is powering a constant-impedance load, higher voltage
also produces higher current. The electronic flash circuitry in the
camera probably behaves this way. Higher battery voltage probably gives
faster flash recharging, but also puts more stress on the flash
circuitry.

In the past, when NiCd batteries were uncommon (and NiMH unheard of),
some manufacturers built external flash units that were designed to use
alkaline batteries, and the internal resistance of the batteries was
what limited recharge current to a level the circuitry was designed for.
If you used NiCd batteries in these flash units, they would overheat.

I'd call that bad design, but it did happen.

Dave
Anonymous
August 24, 2005 8:09:27 PM

Archived from groups: rec.photo.digital (More info?)

In article <dei63m$apt$1@mughi.cs.ubc.ca>,
davem@cs.ubc.ca (Dave Martindale) wrote:

> some manufacturers built external flash units that were designed to use
> alkaline batteries, and the internal resistance of the batteries was
> what limited recharge current to a level the circuitry was designed for.
> If you used NiCd batteries in these flash units, they would overheat.
>
> I'd call that bad design, but it did happen.

Or worse.

Sea and Sea were selling electronic flash units for Scuba that were not
vented properly for NiMh cells. If one used NiCd cells everything was
fine. But some users of NiMh cells had their flash explode during use.

Today their strobe are vented for NiMh cells but you should always check
with the manufacturer of the item you want to use why they specifically
tell you to use a specific type of cell.

--
To reply no_ HPMarketing Corp.
Anonymous
August 24, 2005 8:09:28 PM

Archived from groups: rec.photo.digital (More info?)

On Wed, 24 Aug 2005 12:15:57 -0400, Bob Salomon wrote:

> Sea and Sea were selling electronic flash units for Scuba that were not
> vented properly for NiMh cells. If one used NiCd cells everything was
> fine. But some users of NiMh cells had their flash explode during use.
>
> Today their strobe are vented for NiMh cells but you should always check
> with the manufacturer of the item you want to use why they specifically
> tell you to use a specific type of cell.

Why is that? Though NiCad cells have lower capacity, they have
lower internal resistance and should be able to deliver greater
currents than NiMh cells of the same size and type. But then I'm
not sure if you're referring to venting of heat or something else.
Anonymous
August 24, 2005 8:09:29 PM

Archived from groups: rec.photo.digital (More info?)

In article <pddpg1lkcn19n8g35670iq2c652h2rf19j@4ax.com>,
ASAAR <caught@22.com> wrote:

> if you're referring to venting of heat or something else.

Outgassing from the cell during use.

--
To reply no_ HPMarketing Corp.
Anonymous
August 24, 2005 8:11:55 PM

Archived from groups: rec.photo.digital (More info?)

Prometheus@newbrain.demon.co.uk writes:

>The camera will use a regulator(s) to supply the various circuits inside
>it with power. If it is a simple linear reg. then it will run warmer
>with a higher battery voltage because it has to drop more volts, the
>current is unaltered although it is taking higher power from the
>battery. If it is a switching reg. then for higher a battery voltage
>the input current will reduce thus maintaining a consistent power
>dissipation in the reg. and power consumption from the battery. Since
>switching regs are much more efficient and can operate where the input
>is less than the required output (or both +ve & -ve lines are required)
>they are preferentially used.

For the electronics power, you're probably right. But the electronic
flash circuitry probably does not go through the regulator, because the
current demand is so high and because the supply voltage doesn't need to
be regulated. Similarly, motors may be powered directly from the supply
voltage instead of regulated power.

Dave
August 24, 2005 10:18:03 PM

Archived from groups: rec.photo.digital (More info?)

In article <dei68b$apt$2@mughi.cs.ubc.ca>, Dave Martindale
<davem@cs.ubc.ca> writes
>Prometheus@newbrain.demon.co.uk writes:
>
>>The camera will use a regulator(s) to supply the various circuits inside
>>it with power. If it is a simple linear reg. then it will run warmer
>>with a higher battery voltage because it has to drop more volts, the
>>current is unaltered although it is taking higher power from the
>>battery. If it is a switching reg. then for higher a battery voltage
>>the input current will reduce thus maintaining a consistent power
>>dissipation in the reg. and power consumption from the battery. Since
>>switching regs are much more efficient and can operate where the input
>>is less than the required output (or both +ve & -ve lines are required)
>>they are preferentially used.
>
>For the electronics power, you're probably right. But the electronic
>flash circuitry probably does not go through the regulator, because the
>current demand is so high and because the supply voltage doesn't need to
>be regulated. Similarly, motors may be powered directly from the supply
>voltage instead of regulated power.

Whilst the inverter for the flash is unlikely to be regulated I would be
astonished if the motors which need precise control are not.

--
Ian G8ILZ
Anonymous
August 24, 2005 11:50:39 PM

Archived from groups: rec.photo.digital (More info?)

Prometheus@newbrain.demon.co.uk writes:

>>Similarly, motors may be powered directly from the supply
>>voltage instead of regulated power.

>Whilst the inverter for the flash is unlikely to be regulated I would be
>astonished if the motors which need precise control are not.

Most motor control circuits achieve precise control of motors without
voltage regulation of the drive power.

Stepper motor drivers achieve precise control of position via the
frequency of the drive waveform, and may also control torque through
current control - while using an unregulated DC supply.

Servo motors use encoder feedback from the motor for precise control of
position.

DC motors can use encoder feedback, open-circuit voltage, or current
measurement to maintain nearly constant speed under load - all without
regulated supply voltage. This type of control works better than
simply supplying regulated voltage to the motor because it compensates
for load.

Basically, while motors *can* be driven from regulated voltage, they are
traditionally powered from the unregulated power bus because it
drastically reduces the size of the regulated power supply needed.

Dave
Anonymous
August 25, 2005 5:38:08 AM

Archived from groups: rec.photo.digital (More info?)

Pete D <no@email.com> wrote:

>"Joseph Meehan" <sligojoe_Spamno@hotmail.com> wrote in message
>news:IxPOe.43918$gB.26562@tornado.ohiordc.rr.com...
>> ASAAR wrote:
>>> On Tue, 23 Aug 2005 19:57:27 -0400, Morton Linder wrote:
>>>
>>>> An earlier discussion of Lithium AA cells regarding film cameras a
>>>> few years ago revealed that, due to lower internal resistance, Li
>>>> cells can deliver a higher current flow (same voltage) which can
>>>> heat up and
>>>> destroy some sensitive electronic components.
>>>
>>> Absolutely not true. At a given voltage (under load), the camera
>>> will draw the same current, whether the source is alkaline or
>>> lithium, whether they are AAA, AA, C or D cells.
>>
>> But the issue is it appears that Lithium batteries deliver a higher
>> voltage under load, and therefore have the potential to deliver more
>> current.

>And therefore the higher voltage should equate to lower current!

All this speculation...

The bottom line is this: if the manufacturer says
don't use a certain type or types of batteries, then
DON'T DO IT.

Who knows why? Maybe they just don't like the brand,
but I'd not bet on it.

----- Paul J. Gans
August 25, 2005 11:05:04 PM

Archived from groups: rec.photo.digital (More info?)

In article <deij2f$dps$1@mughi.cs.ubc.ca>, Dave Martindale
<davem@cs.ubc.ca> writes
>Prometheus@newbrain.demon.co.uk writes:
>
>>>Similarly, motors may be powered directly from the supply
>>>voltage instead of regulated power.
>
>>Whilst the inverter for the flash is unlikely to be regulated I would be
>>astonished if the motors which need precise control are not.
>
>Most motor control circuits achieve precise control of motors without
>voltage regulation of the drive power.

I did not mean that they could not be, in fact I would never rely on the
supply voltage for control.

>Stepper motor drivers achieve precise control of position via the
>frequency of the drive waveform, and may also control torque through
>current control - while using an unregulated DC supply.

Sorry, but precise control of position depends on the number of pulses,
the frequency (more properly pulse rate) determines the rate of change
of position.

>Servo motors use encoder feedback from the motor for precise control of
>position.

Have you considered the time constant of the loop and the effect due to
fluctuations in supply voltage.

>DC motors can use encoder feedback, open-circuit voltage, or current
>measurement to maintain nearly constant speed under load - all without
>regulated supply voltage. This type of control works better than
>simply supplying regulated voltage to the motor because it compensates
>for load.

Obviously.

>Basically, while motors *can* be driven from regulated voltage, they are
>traditionally powered from the unregulated power bus because it
>drastically reduces the size of the regulated power supply needed.

The kit we designed with stepper motors always used a regulated supply,
it gives a better engineering control and enhanced operating life.
--
Ian G8ILZ
Anonymous
August 25, 2005 11:05:05 PM

Archived from groups: rec.photo.digital (More info?)

Prometheus@newbrain.demon.co.uk writes:

>>Stepper motor drivers achieve precise control of position via the
>>frequency of the drive waveform, and may also control torque through
>>current control - while using an unregulated DC supply.

>Sorry, but precise control of position depends on the number of pulses,
>the frequency (more properly pulse rate) determines the rate of change
>of position.

Sophisticated stepper drivers synthesise sine waves with a phase shift
of 90 degrees (or 120, depending on the numbers of coils in the motor),
while simpler drivers use square waves. It makes sense to talk about
frequency and phase of both sine and square waves, while "pulse rate"
just seems wrong in the context of sine waves. Basically, the motor is
a synchronous motor rotating in lock-step with the input signal, whether
sine or square. If you want to be precise, speed is determined by
frequency, and position is determined by the integral of frequency.

>>Servo motors use encoder feedback from the motor for precise control of
>>position.

>Have you considered the time constant of the loop and the effect due to
>fluctuations in supply voltage.

As long as the servo amplifier has enough feedback, the output voltage
is pretty much independent of input voltage as long as the latter
remains within limits.

>The kit we designed with stepper motors always used a regulated supply,
>it gives a better engineering control and enhanced operating life.

And all of the stepper-drive systems I've seen did not need a regulated
supply for proper operation. If you're building a mains-operated device
and don't mind wasting some space and energy, regulating the stepper
drive voltage probably makes sense. But if you're trying for minimum
space and power, it makes sense to avoid regulating any supply you don't
need to.

Dave
!