solar panel & lithium battery=bomb?

[dukeleto]

gday all!
I've got a beaudie of a little digital camera which runs on a proprietary lithium-ion cell (3.6V 900mAh). This summer I'll be trekking for 2 months /ubbthreads/images/graemlins/smile.gif
with no access to electricity /ubbthreads/images/graemlins/crazy.gif
I've got a small good quality solar panel (6V 50ma) that could be plugged onto the DC in on the camera; would this be dangerous /ubbthreads/images/graemlins/confused.gif
The transformer says it delivers 5VDC @ 1700ma (that's probably a typo on the transformer 'caus it charges at the most in 5 hours, for 900mAh: sounds more like the trasformer delivers 170ma) so I'd never get enough current with the solar panel. Will anything happen (ie a slower charge) or will the camera just not charge the battery??

Thanks for any opinions (just about necessarily better informed than mine /ubbthreads/images/graemlins/wink.gif )

 

[zmoz]

It probably would charge, although quite slow. With a 900ma battery it would take more than 18 hours in full sun to charge.

 

[Entropy]

[ QUOTE ]
dukeleto said:
gday all!
I've got a beaudie of a little digital camera which runs on a proprietary lithium-ion cell (3.6V 900mAh). This summer I'll be trekking for 2 months /ubbthreads/images/graemlins/smile.gif
with no access to electricity /ubbthreads/images/graemlins/crazy.gif
I've got a small good quality solar panel (6V 50ma) that could be plugged onto the DC in on the camera; would this be dangerous /ubbthreads/images/graemlins/confused.gif
The transformer says it delivers 5VDC @ 1700ma (that's probably a typo on the transformer 'caus it charges at the most in 5 hours, for 900mAh: sounds more like the trasformer delivers 170ma) so I'd never get enough current with the solar panel. Will anything happen (ie a slower charge) or will the camera just not charge the battery??

Thanks for any opinions (just about necessarily better informed than mine /ubbthreads/images/graemlins/wink.gif )

[/ QUOTE ]
Depends on the charge controller inside the camera.

It might not be happy about having too little current.

As far as the transformer rating: The amperage rating is its MAX rating. i.e. the most current that can be drawn before the voltage will start sagging/regulator overheats/other fun stuff.

Some switching regulators also become unhappy when completely unloaded.

 

[star882]

"I've got a small good quality solar panel (6V 50ma) that could be plugged onto the DC in on the camera; would this be dangerous
The transformer says it delivers 5VDC @ 1700ma (that's probably a typo on the transformer 'caus it charges at the most in 5 hours, for 900mAh: sounds more like the trasformer delivers 170ma) so I'd never get enough current with the solar panel. Will anything happen (ie a slower charge) or will the camera just not charge the battery??"
I'd use a 12v, >500ma solar panel and a simple SMPS to convert it to regulated 5v.
The electronics in a digital camera can use quite a bit of power.

 

[zmoz]

[ QUOTE ]
star882 said:
I'd use a 12v, >500ma solar panel and a simple SMPS to convert it to regulated 5v.
The electronics in a digital camera can use quite a bit of power.

[/ QUOTE ]

A 12v, 500ma panel would be quite expensive, and quite large.

 

[carbonsparky]

Those rechargeable lithium ion batteries are great, except where there is no place to plug them in.
Your best bet is to buy a spare battery or two and charge them up ahead of time and hope you get a chance to charge them again before you run out.
You probly will want to take some trial photos to get a idea how many you can get from a charge. I have found there are some digital cameras on the market that can go for ever on batteries. My Cannon 3.2Meg is still on its first set of 4 x AA alkalines.
I am not sure if I will even mess with rechargeable batteries. I can buy them in those bulk blister packs for less than 50 cents a cell and at the rate my camera goes through batteries I would be more worried about using up my 32 and 64Meg Compact Flash modules. When I go on vacation the last thing I need to mess with is trying to charge up a set of batteries.
One thing that I did notice on my last outing, was how many people don't know how to operate their cameras. Things like how to turn off your flash when taking pictures through glass. Of course this is also a good trick to make those batteries last a bit longer.

 

[highlandsun]

I suppose if you never use the flash you'll be OK. My Kodak DC265 eats batteries fast, I always have a spare set of freshly charged 1800mAH NiMH AAs ready to swap in when I'm on vacation. I use a 128MB memory card, and fill it up in a day or two's hiking. I've had to switch to lower resolutions to extend my picture-taking, which is a drag because I want full-rez images.

 

[highlandsun]

This panel might be a better choice...

http://www.global-merchants.com/home/panel2.htm

 

[dukeleto]

Thanks for the comments!
Quite right zmoz, "A 12v, 500ma panel would be quite expensive, and quite large."
Specially for trekking /ubbthreads/images/graemlins/grin.gif
I can manage about 100 flash-off photos on the one battery, which is a bit short for 2 months + 1GB of memory cards...
By the way, Carbonsparky, I quite agree with you about the number of people who don't know what to do about the flash. Above ~ 2-3 m it's no use & thru glass it actually makes things worse /ubbthreads/images/graemlins/smile.gif
The cool thing about my solar panel is that it's rollable i.e. flexible : great for stuffing in a backpack, even if its output power is way under the one mentionned by highlandsun.
I am now realizing to the full extent how wrong I was to buy a camera that doesn't take AA's /ubbthreads/images/graemlins/crazy.gif

 

[N162E]

If you want to really save power with your digital camera turn off the LCD viewer or at least set it for a very short review time, if you must use it. If your camera has adjustable power shut down set it for a short time also, like 2-5 minutes. Taking the pictures is not the main drain of power in a digital camera, the viewing and flash options are what use it up. /ubbthreads/images/graemlins/smile.gif

 

[e=mc²]

Ditto to what N162E said. By switching off my LCD, and by using flash only when absolutely necessary, I get at least twice, if not more mileage on a set of batteries than the default settings which are LCD on and flash set to auto. The flash even goes off at high noon with that default setting, and it isn't totally necessary. Sometime it is, like for fill -in for very shadowy lines on faces, but I usually just reposition my subject anyway for optimum effect.


Ed.

 

[Alledges]

Depending on the camera, you might be able to use an external battery pack. Maybe rig something with NiMH AAs. Then you can charge them in a configuration suitable to your solar panel and use them in the pack's config. The NiMHs recharge cycle and capacity might suffer, but they wouldn't explode and abusing NiMH is cheaper / safer than destroying lithium. Your other concern is memory storage. Are you bringing many memory cards, uploading to portable hard drive or laptop, or reducing image quality to maximize photos per card?

 

[dukeleto]

Alledges: I'm lucky enough to have a substantial supply of SD cards borrowed from friends & parents: 2*256MB + 4*128 !
After testing yesterday, with flash & LCD off I can take 150 photos on one charge

 

[Graham]

I agree with the idea of an external battery pack - I've seen more of these available here recently.

The ones I've seen are purpose-made for digital cameras - they consist of a small case with a screw on top which allows it to attach to the bottom of the camera via the tripod screw mount. Then you just plug it into the cameras DC power socket and you're on your way. The ones I've seen use AAs, so you can either put in NiMHs or just carry a pack of alkalines with you..

A pretty good idea if you ask me, especially using the tripod mount to keep the pack firmly attached to the camera yet out of the way..

This is the sort of thing I mean, although the ones I've seen are cheaper and just allow the use of AA batteries.

Graham

 

[carbonsparky]

That roll up solar cell sounds kind of neat. Some of the new things are so wild. I have been waiting for the roll up organic leds to hit the market. How about a roll up flashlight?

I was going to build a external battery pack for my HP, but now that I have my Cannon I don't need it. I am amazed by the difference in battery consumption in digital cams.

Dukeleto, hope your trip is great one. In the modern world it is hard to imangine finding anyplace with out a AC outlet somewhere, but they still to exist.

 

[PsycoBob[Q2]]

How 'bout a roll-up light panel? Ever want to go camping, and have the inside of your tent have 'nightlight' and 'artificial-dawn' settings? /ubbthreads/images/graemlins/sleepy.gif /ubbthreads/images/graemlins/eek.gif

Hey- Doublesided system: O-Led light on one side, Amorphous-Solar panel on the other, Plastic-polymer battery pack sandwiched between! /ubbthreads/images/graemlins/drool.gif

 

[highlandsun]

Sanyo used to market a transparent Amorton, flexible and transparent a-Si cells. I tried to order some to line my car windows (better than window tint!) but they never exported it to the US. A shame.

Throw a peltier junction in there and you've got it all, I think. Turn light & heat into electricity, turn electricity back into heat or light...

 

[dukeleto]

Thanks alot guys, the battery pack solution works great!
I first tried (after 5 deep breaths & a "just in case you blow up" goodbye to my camera /ubbthreads/images/graemlins/grin.gif ) with a DC adjustable power supply and turned down the current progressively to see what happens: under 100mA the camera very cleanly shuts down the charging circuit and above 100, it accepts what it gets. At 100 mA it took 3 times as long to charge the flat battery as with the camera's DC adaptor.
No probs after that in trying it on a homemade battery pack; with 4 nimh AAs or 5 alkalines (I put in a 6V cut off just in case ) I can charge the lithium battery or just operate the cam without the lithium.
Using batteries to charge batteries /ubbthreads/images/graemlins/rolleyes.gif

On another note: two months with no electric plug for sure can be found in deep south-western China (N-E of Tibet). I went close to there 2 years ago; a few houses actually had plugs but told me that they rarely even tried them 'cos weeks without power are more freqent than days with...
Cheers,
Olivier

 

[highlandsun]

I've been taking one of these Radio Shack Power Banks with me on all my trips recently - item # 273-1900, charges 2 or 4 NiMH AAs, can provide 3, 4.5, 6, 7.5, and 9V at up to 1A to run other devices. It runs on 90 to 240VAC, you just need plug adapters... Very convenient.

 

[LoneRebel]

dukeleto, I attempted charging a Lithium-Ion battery with a 10v 150ma solar panel and it simply wouldnt charge. I opened up the battery pack and noticed a nice circuit board attached to the batteries. Apparently my charging methodology wasnt making the circuit happy. So I just ripped out the circuit and charged it up no problem. The circuit probably performs voltage monitoring so you cant dangerously deplete the battery. So I might solder that back on along with a couple leads to attach directly to the solar panel.

Does anyone know what voltage a 3.6v battery should be when fully charged? Mine seems to top off around 4v.