Battery Question

[d_brown]

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Alexander:

 

Good work! I would also like to see detailed photos of what you have done.

 

I opened an M8 battery case some time ago and saved it. There is room inside the case for an adapter which would hold three AAA cells. That would give 700 shots. Let us know and I'll make an adapter and post photos and details here.

 

Thanks,

Dale

[atufte]

From joy to frustration....after making this and being happy as a kite in getting more (longer) power to my M8, i was very frustrated after loading the picture into PS, every third image has horizontal signal noise (lines), so something is definitely wrong, see example... (sorry for another a cat picture but changing back to a original battery turns everything back to normal, thankfully)

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[farnz]

[SJP]

It looks like the voltage is fluctuating, so you need to include a voltage stabilisation circuit. Probably a solid state regulator can be found with the exact voltage & can be mounted into the battery housing (as close to the camera as possible basically)

 

To improve the present set-up you need to make sure the wires are thick enough, about 1mm multistrand core should do it. Also you could fit a rather big electrolytic capacitor into the (now empty) battery case, that should remove most of the voltage ripple.

[farnz]

It looks like the voltage is fluctuating, so you need to include a voltage stabilisation circuit. Probably a solid state regulator can be found with the exact voltage & can be mounted into the battery housing (as close to the camera as possible basically)

 

To improve the present set-up you need to make sure the wires are thick enough, about 1mm multistrand core should do it. Also you could fit a rather big electrolytic capacitor into the (now empty) battery case, that should remove most of the voltage ripple.

Stephen,

With the greatest respect, these sound to be solutions for stabilising ac voltage sources (ie smoothed rectification) but Alexander used a dc source supplied from AA batteries.

 

I agree that the wires need to be thick to eliminate volt drop but I don't understand how a capacitor will help to stabilise the output from a battery; one side of the electrolytic would charge and then nothing would happen would it? (Congratulations on your 2000th post by the way.)

 

Pete.

[SJP]

Stephen,

With the greatest respect, these sound to be solutions for stabilising ac voltage sources (ie smoothed rectification) but Alexander used a dc source supplied from AA batteries.

 

I agree that the wires need to be thick to eliminate volt drop but I don't understand how a capacitor will help to stabilise the output from a battery; one side of the electrolytic would charge and then nothing would happen would it? (Congratulations on your 2000th post by the way.)

 

Pete.

Pete, thanks for the compliment although one could argue that it indicates a one track mind and nothing else to do with my life

 

Anyway, to address your points:

- No not AC obviously, I mean a DC voltage stabiliser/regulator see wikipedia for the generic & somewhat simplified circuit. These can be bought as a single package semiconductors for positive and negative voltage control and come in various output voltage and current ranges. I seem to remember that someone actually measured the M8 current demand (was it Mark Norton?) but I would be surprised if it was above 500mA peak. Also note that these things have a minimum voltage drop typically of 0.7 volts so you need to feed a 3.8 V regulator with at least 4.5 volts so 4 rechargable AA cells (or more) should do the trick. Anyway these are very simple to wire, basically three prongs IN (4.8 volts, COMMON (e.g. the negative wire if it is a positive regulator) and OUT the desired stabilised voltage (3.8 V or whatever it should be). Purists attach a 100 nF polyester and a 5 muF electrolytic capacitor parallel to the output. See datasheets here for example.

 

- The cheap and nasty solution involves placing a capacitor close to the camera terminals. This should act as a buffer to maintain a constant (or more constant) voltage as it can supplement energy if the voltage from the batteries drops due to a current surge. This is not quite as good as a regulator admittedly. Note that a big (in capacity) capacitor is a standard fixture in DC power supplies for this reason. EDIT: phrased differently the storage capacitor reduces the internal resistance of the power supply.

 

The best is to go to an electronic parts store & ask for advice. These guys usally know more than their clients about all the ins & outs of modern electronics. I guess I could provide a schematic if somone can tell me the V and I-max values.

Edited February 20, 2010 by SJP

[farnz]

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Thanks for the explanation, Stephen, now I see which way you were proposing to stabilise the input voltage.

 

Pete.

[atufte]

How about this one, will this do the trick...?

 

Adjustable-Voltage Regulator LM317T - RadioShack.com

[atufte]

Hi again

 

I used thin leads, can this alone be the problem?, i used leads like this (about 6cm long)

 

 

http://files.jeelabs.org/2009/09/DSC_0498.jpg

[SJP]

LM317T looks good to me! I guess you know how to deal with the external wiring, variable resistance etc. see schematic in the datasheet http://www.national.com/ds/LM/LM117.pdf

 

This thing is rated at 1.5A continuous but has internal T-protection & looks pretty bomb proof to me. I guess you will want to use the TO-220 housing & mount it inside the (empty) M8/M9 battery. EDIT: ignore the last remark I see that the type T is TO-220 housing.

Edited February 20, 2010 by SJP

[SJP]

Hi again

 

I used thin leads, can this alone be the problem?, i used leads like this (about 6cm long)

 

 

http://files.jeelabs.org/2009/09/DSC_0498.jpg

thicker leads will definately help this is in the 0.6mm ballpark I expect.

[don_panko]

Just curious why every third image is affected. That doesn't sound like a voltage problem to me unless you are running in multiframe/continuous mode. Before you invest more in parts why not connect a digital voltmeter and take readings before and after each shot to confirm that you have a problem. With extra capacity, voltage drop is not likely. Perhaps a loose connection.

 

My assumption all along has been that you are replacing the cells within the Leica battery with external cells of larger capacity and that way any special circuitry inside the Leica battery pack is unchanged. True?

[atufte]

LM317T looks good to me! I guess you know how to deal with the external wiring, variable resistance etc. see schematic in the datasheet http://www.national.com/ds/LM/LM117.pdf

 

This thing is rated at 1.5A continuous but has internal T-protection & looks pretty bomb proof to me. I guess you will want to use the TO-220 housing & mount it inside the (empty) M8/M9 battery. EDIT: ignore the last remark I see that the type T is TO-220 housing.

 

Thanks...

 

But i'm really green on this things and would not know how to mount and setup this thing, so any help/guidance will be wildly appreciated ...thx

[SJP]

Thanks...

 

But i'm really green on this things and would not know how to mount and setup this thing, so any help/guidance will be wildly appreciated ...thx

The data sheet for the LM117 family I posted before gives the generic circuit on page 1, I would personally just hook up the parts as a "christmas tree" i.e. just solder them together without mounting on a circuit board. This looks like cr@p but is OK for a simple circuit like this, if neccesary slip some insulation over the various wires or use insulation tape.

 

If you are not experienced with this then the only advice I can give is give it a try first outside the camera - a LM317T is not a very expensive component after all, just try soldering this together first outside the battery pack and see if it works. If it works OK it should give enough confidence to mount into the battery pack. Note that variable resistance R2 should be a mini version (called a trimmer in NL, which may be the international term)

 

I guess you will need to measure/adjust the voltage with a simple voltmeter, also readily available at radio shack for 10 euro/dollars or so.

[atufte]

The data sheet for the LM117 family I posted before gives the generic circuit on page 1, I would personally just hook up the parts as a "christmas tree" i.e. just solder them together without mounting on a circuit board. This looks like cr@p but is OK for a simple circuit like this, if neccesary slip some insulation over the various wires or use insulation tape.

 

If you are not experienced with this then the only advice I can give is give it a try first outside the camera - a LM317T is not a very expensive component after all, just try soldering this together first outside the battery pack and see if it works. If it works OK it should give enough confidence to mount into the battery pack. Note that variable resistance R2 should be a mini version (called a trimmer in NL, which may be the international term)

 

I guess you will need to measure/adjust the voltage with a simple voltmeter, also readily available at radio shack for 10 euro/dollars or so.

 

Thanks again

 

I have a voltmeter, so that's ok, but how do i adjust this device for 3.7 V...?

 

Sorry for all the stupid questions

 

Thx...

[atufte]

Another thing that comes to mind is, what does the circuit board inside the M8 battery do?

Everything i connect goes through this circuit board, and i would think this circuit board had

a regulator/capasitor, if not what is it's purpose...?

[farnz]

Another thing that comes to mind is, what does the circuit board inside the M8 battery do?

Everything i connect goes through this circuit board, and i would think this circuit board had

a regulator/capasitor, if not what is it's purpose...?

It's a safety circuit that's there to prevent the Li-Ion battery from overcharging and either catching fire or exploding.

 

Pete.

[SJP]

If you wire stuff together as indicated in the schematic then the variable resistance (trimmer) R2 can be used to adjust the output voltage.

 

If you believe the datasheet then you could even use the equation to figure out the resistances, let's see 3.7 = 1.25(1+R2/R1) & forget the rest as the current is only 50 microamps, so then 3.7/1.25 -1 = 1.96 = R2/R1 then we go to the preffered numbers for resistances and the E48 series gives 196 exactly as a option so you could use R2 = 1960 ohm and R1 = 1000 ohm, color coded repectively 1.96K = Brown, white, blue, brown, red and 1K = Brown, black, black, brown, red see here for a resistance color band device.

[nigelb]

It would be safer to go back to your original idea of a higher power lithium battery that provides a niminal 3.7V instead of standard AAs that provide 4.5V and messing around with these regulators. Its the voltage your camera was designed to work off.

 

Thinking about it.... If you are using 3 x AA 2400mAh batteries in series you have a 4.5V 2400mAh pack. The standard batteries are 1900mAh, thats just a 25% increase in power. To suggest an increase in battery life from a handfull of pics to nearly 1700 pics from an increase in battery power of 25% sounds ridiculous. I still think that the problem is with your old batteries and/or charger.

 

If you continue to mess around like this without knowing what you are doing you are in danger of permanently damaging your camera.

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Look here: Leica M

[atufte]

It would be safer to go back to your original idea of a higher power lithium battery that provides a niminal 3.7V instead of standard AAs that provide 4.5V and messing around with these regulators. Its the voltage your camera was designed to work off.

 

Thinking about it.... If you are using 3 x AA 2400mAh batteries in series you have a 4.5V 2400mAh pack. The standard batteries are 1900mAh, thats just a 25% increase in power. To suggest an increase in battery life from a handfull of pics to nearly 1700 pics from an increase in battery power of 25% sounds ridiculous. I still think that the problem is with your old batteries and/or charger.

 

If you continue to mess around like this without knowing what you are doing you are in danger of permanently damaging your camera.

 

I got 1678 exposures from one charge, so your statement about this being ridiculous is beyond me...?

And i used 3 AA 2700mAh batteries, not 2400mAh, and what this tell's me is just how bad

the original M8/9 batteries are (the original M8 batteries are 1800mAh not 1900), i have several, (and they are new and i perfect condition)

I do not think this is any dangerous since i constantly use a voltmeter to check that the

voltage is under not over the recommended strength...but i will not do any more testing before

i get a regulator, and one of the reasons i chose AA is the possibility to use batteries from your local kiosk or supermarked, if i run empty...