Low temperature power pack for camera.

[Wayland]

Many years ago I had a handy gadget for my A series Canon cameras that linked a small battery holder carried inside the clothing to the camera outside via a cable for shooting in very low temperatures.

My intention is to make something similar for a Fuji x10 using the CP-50 DC coupler unit.

http://shop.fujifilm.co.uk/cp-50.html

This is where I need a little bit of technical advice. It's a long time since I learned some basic physics at school.

As far as I can see, the AC-5VX AC power adapter that this is supposed to couple with produces an output of 5 Volts at 1.5 Amps. (I hope I'm not missing anything obvious.)

http://shop.fujifilm.co.uk/ac-5vx.html

So, is there any reason that this power could not be provided by a rechargeable USB style power pack along the lines of this one?

http://www.dealextreme.com/p/rechargeable-dual-usb-10000mah-emergency-battery-pack-w-adapter-for-cell-phone-more-110237

If that pack is not suitable, does anyone know something else that would do the job?

 

[rik_uk3]

USB phone charger, uses AA including rechargables
http://www.dealextreme.com/p/aa-battery-usb-emergency-backup-power-and-charger-pack-15048
will last you longer than the power cell you listed.

 

[udamiano]

the output for the charger is 5V at 1.5A (according to the link) and you need 5V at 1.5 A DC, so really all you need is a cable that is USB one end and a power male jack the other ?

The problem is going to be load. the unit above only produces .001 amp per hour on load which might not be enough to power the camera

 

[udamiano]

OK just checked and the Fuji batteries for that model produce 3.7V at 1000mAh, so load is ok, but voltage slightly higher, but then again the adapter unit requires 5v so you should be ok with just a cable.

 

[rik_uk3]

For £2.50 its worth a go, at worse you get a charger for your mobile that runs off AA's.

 

[Wayland]

At worst I fry a £400 camera.

One of the reviews point out that there is no voltage regulation on the AA pack and it delivers 6.4V to 5.4V which is a bit high.

 

[rik_uk3]

Use it to charge up the battery pack then. Its not fried my Galaxy S2, old G1 or my son's HD7 yet.

 

[bikething]

OK just checked and the Fuji batteries for that model produce 3.7V at 1000mAh, so load is ok, but voltage slightly higher, but then again the adapter unit requires 5v so you should be ok with just a cable.

What he said

The CP-50 drops the voltage from 5V to 3.7V.

The ac-5VX power supply can deliver a MAXIMUM of 1.5A at 5 volts. You could be drawing a lot less current in actual use as this depends on the load rather than the supply, so as long as your battery pack delivers the same voltage and is capable of supplying the same current (or more) as the power supply you should be good to go

 

[Wayland]

One thing I couldn't work out is if the 1.5A is divided across both sockets or whether it would be fully available through just one of them?

 

[udamiano]

One thing I couldn't work out is if the 1.5A is divided across both sockets or whether it would be fully available through just one of them?

The problem is that unless I can see the little circuit diagram on the adapter (its on the label), I can't tell. There should be a common negative (-VCC) and +VCC (voltage current constant) so Im am guess that one cable provides the current and voltage and the other the return. to be 100% though I would need to put a meter across the terminals.

But I'm guess on one

 

[Wayland]

Ah Ha.. I should have looked closer at the back picture of the power pack.

That would seem to suggest that each socket delivers the required power.

 

[udamiano]

yes both Socket 1 and 2 according to the above output at 5v at 1.5A

and the USB is

 

[cbr6fs]

Fair bit of confusion here.

The voltage is what you need to get right, the amperage has absolutely nothing to do with "load".

A battery packs amperage is it's amount of stored energy.
Think of amps as the fuel tank and the voltage as the motor, you can have a fuel tank as big as you wish it doesn't make the motor go any faster.

There is a small exception is this and that is the packs "C rating"
Each pack will have a "charge C rating" and a "discharge C rating"

As an example lets say we have a 5000mAh pack with a 1C charge rating.
That means that we can charge this pack at 5amps.

If it had a 2C rating we could charge at 10amps and so on.

Watts is the method we use to measure load, watts is calculated by voltage x amp draw.
a 4.2v pack that's supplying 10 amps will be rated at 42 watts


Most Lithium based batteries will be able to discharge far more power than several cameras can draw.
Even older NiMh and NiCd chemistry cells should be more than enough.



My advice would be to stay away from Lithium based cells as they are a LOT more sensitive to the cold than NiMh, they're also very sensitive to voltage, an example of which would be:
If you charged your Lithium cells in the cold (4.2v being the stop voltage) then you moved them into a warmer location their voltage would increase.
This is a problem on Lithium cells as if their voltage goes to high at best you risk ruining the pack, at worst they will flare up and cause a fire.

I would find a battery pack that accepts AA cells.
By far the best NiMh chemistry AA cells i've found so far are the "Sanyo Eneloops" they cope well with the cold and are a "low static Discharge" type cell in that they loose very little voltage when sat doing nothing.
They're also exceptional at providing higher current if need be.

 

[Wayland]

So I should just need to butcher a USB lead and attach a plug that fits to the DC coupler and Robert is your Dad's brother.

Sounds like a good one to me and should save all that faffing around with spare batteries stored inside my parka.

I reckon a couple of those power packs charged up before I fly out should see me through a fortnights shooting next year.

 

[Wayland]

Cbr6fs: Your post came up while I was posting.

If this runs to plan the battery pack will be running at around normal temperatures because it will stored inside my clothing with just the lead outside running to the camera.

Charging should also be done at normal room temperature as well.

Are there likely to be any problems given those conditions?

 

[udamiano]

sorry to clear thing up, yes your right load is not a measure of amperage. Amps are a measure of the force of the current (I)as it flows, (V)olts are the amount of energy this flow has. and Watts are the amount of (p)ower that is transferred into work. and resistance is the amount of restriction to flow.
taking in the basic formula V=IxR. and P = ExI the total requirements for the circuit should be fairly easy to work out

Cbr6fs is quite correct in his statement about load

The charge ratio for this would not be a problem as this is still done using the devices normal charger. The question was whether or not the device could provide the necessary requirement to the camera for it to work.

 

[IanM]

That seems as if the power is sorted but is the camera OK with low temperatures? For my old pre-digital camera to get it to work at -20ºC or below I had to get the lubrication cleaned off and replaced or else the more viscous oil would affect the shutter speeds. I doubt if this appies to the modern digital camera but I note that your camera specifications quote a minimum use temperature of 0ºC. I wonder why?

Perhaps you could cold soak the camera and adapter in a freezer at -18ºC for 24 hours or so then plug in your warm battery and see what sort of photos you get.

 

[cbr6fs]

Cbr6fs: Your post came up while I was posting.

If this runs to plan the battery pack will be running at around normal temperatures because it will stored inside my clothing with just the lead outside running to the camera.

Charging should also be done at normal room temperature as well.

Are there likely to be any problems given those conditions?

That sounds like both chemistry cells will work well in those conditions.


Personally though i would use a device that accepts AA batteries and use NiMh batteries though.

Lithium cells have come on dramatically in the last 10 years, i use them all the time in my phones, laptops and radio controlled, cars, planes etc.
For larger voltages and storage amperage they really cannot be beaten for size and weight.

BUT even though they are much improved they are still a fair bit more fragile than AA batteries, both with charging and use.


I have my cell phone on the side of my bumbag around 2" away from my "family jewels" and i'm confident they are well protected.

With the Lithium based battery packs though the cells and voltage circuitry does not meet the same standards as cell phone batteries, plus most cell phones are not much bigger than 1500mAh and 4.2v.
That's not a lot of energy even if the worst happens.

Over 5000mAh and 2cell (i.e. 8.4v) and the stored energy is a LOT more, and any defect has a lot more dramatic results.


If that happens inside your jacket and your in artic conditions then the best you can hope for is that your jacket is severely burnt.
This in itself is life threatening in those weather conditions.


So as i say i would buy a pack that accepts AA batteries, that way they're safer plus if you have any problems with the batteries you can find AA batteries pretty much anywhere around the world.

 

[Wayland]

That seems as if the power is sorted but is the camera OK with low temperatures? For my old pre-digital camera to get it to work at -20ºC or below I had to get the lubrication cleaned off and replaced or else the more viscous oil would affect the shutter speeds. I doubt if this appies to the modern digital camera but I note that your camera specifications quote a minimum use temperature of 0ºC. I wonder why?

Perhaps you could cold soak the camera and adapter in a freezer at -18ºC for 24 hours or so then plug in your warm battery and see what sort of photos you get.

Going on past experience it is the battery that sets out the minimum operating temperature spec. for most cameras.

The next thing to conk out is the LCD which depending on type has a lowest recommended operating temp of about -10c although I have used them much lower than that.

The X10 has a decent optical viewfinder should the LCD get too sluggish.

Keeping the battery inside clothing and the camera in a pocket wrapped in a dry bag to protect from condensation should keep it running with a little care.

My G10 worked happily down to -16c this year by swapping batteries in and out of pockets so I'm hoping this will do the job with less fuss.

That sounds like both chemistry cells will work well in those conditions.


Personally though i would use a device that accepts AA batteries and use NiMh batteries though.

Lithium cells have come on dramatically in the last 10 years, i use them all the time in my phones, laptops and radio controlled, cars, planes etc.
For larger voltages and storage amperage they really cannot be beaten for size and weight.

BUT even though they are much improved they are still a fair bit more fragile than AA batteries, both with charging and use.


I have my cell phone on the side of my bumbag around 2" away from my "family jewels" and i'm confident they are well protected.

With the Lithium based battery packs though the cells and voltage circuitry does not meet the same standards as cell phone batteries, plus most cell phones are not much bigger than 1500mAh and 4.2v.
That's not a lot of energy even if the worst happens.

Over 5000mAh and 2cell (i.e. 8.4v) and the stored energy is a LOT more, and any defect has a lot more dramatic results.


If that happens inside your jacket and your in artic conditions then the best you can hope for is that your jacket is severely burnt.
This in itself is life threatening in those weather conditions.


So as i say i would buy a pack that accepts AA batteries, that way they're safer plus if you have any problems with the batteries you can find AA batteries pretty much anywhere around the world.

Fair points there, I guess I would need to use at least 4 cells and a bit of circuitry to drop the voltage to 5v to supply the coupler unit then if I went that way.

 

[cbr6fs]

I am seeing 1.1v from a fully charged Eneloop cell under load, so if you connect 5 in series then this would give you around 5.5v under load and around 1.4v per cell without load so 7v with no load.

Each Eneloop is around 2000mAh, so if you connect 5 in series you get 5.5v and 2000mAh capacity.

If you connected 5 in series and another 5 in parrallel then you would have 10 x AA batteries giving 5.5v but a bigger capacity at 4000mAh.

I know i'm sounding a bit like a poster boy for Eneloop batteries here, but believe me i've tried every variation of AA battery that's out there and the rechargeable Eneloops are better by a fair old margin.

They're also pretty good at colder temps.
http://www.eneloop.info/home/performance-details/low-temperature.html