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Ultimate rechargable AA batteries for Canon camera ?

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Offline waterwingz

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Ultimate rechargable AA batteries for Canon camera ?
« on: 23 / March / 2013, 15:44:39 »
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This might be of interest for those with cameras that use AA batteries. 

From the article :

This one begins with my frustration with the poor rechargeable battery performance in most Canon point-and-shoots using two AA size batteries. Canon cameras that use two AA batteries seem to be pretty much useless with normal NiMH rechargeables, as they last for about 10 shots or so, if you are lucky – that’s because they produce only 2.4 V.
Solution: Use a single LiFePO4 3.2V AA cell coupled with a dummy cell.

http://zapmaker.org/quick/ultimate-rechargable-aa-batteries-for-canon-camera/
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Offline reyalp

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Re: Ultimate rechargable AA batteries for Canon camera ?
« Reply #1 on: 23 / March / 2013, 17:39:58 »
I think the premise of that article is wrong, Canon P&S are designed to work with NiMH, and generally get better life with NiMH than alkaline despite the voltage difference. Canon strongly recommends using NiMH, and it's not as if the designers are ignorant of the differences...

The obvious hyperbole of "last for a bout 10 shots or so" doesn't inspire confidence.

edit:
Of course, actual measurements could certainly be interesting
« Last Edit: 23 / March / 2013, 17:53:20 by reyalp »
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Offline ahull

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Re: Ultimate rechargable AA batteries for Canon camera ?
« Reply #2 on: 23 / March / 2013, 17:54:58 »
Its a useful idea if you already have the LiFePO4 cells lying about, but otherwise I tend to agree with reyalp. the capacity of the battery is the important factor, and these small 104500 LiFePO4 cells are typically around the 600mAh mark, some as low as 200mAh (although the actual capacity of a lot of no-name brands on the internet is often massively overstated, I bought some AAA NiMh recently that claimed a massive 1800mAh I suspect they are the same as the 800mAh ones, they were after all the same price, so I was under no illusion about their likely pedigree).

The increased voltage (3.2V vs. 2.4V for two NiMh AA batteries) shouldn't be a factor in a camera which is designed specifically to use NiMh, (older cameras which are designed for Alkaline cells might care, but probably not, they would either work fine for most of the full capacity  of the NiMh cells, as their discharge curve is generally fairly flat, or simply fail to work at all). In this case you would have to do the experiment... 2 x quality fully charged 2000mAh AA NiMh cells versus 1x 600mAh 104500 LiFePO4, my money is on the NiMh cells with the higher capacity.

If you want to use LiFePO4 batteries, you would be better using them through the external power adapter jack, then you can get some serious capacity batteries.  For example something like these... http://www.hipowergroup.com/products/LiFePO4%20batteries/  3v2 at 50 Ah that should keep your powershot buzzing for quite a while (someone do the maths for me please)  The $100 price tag might put you off though (not including charger :o )... However if you just want an alternative power source to replace the AA batteries in your point and shoot, you might be better to spend your $20 on a bunch of conventional AA NiMh re-chargables (typical capacity for a good named brand is around the 2000 mAh mark, Energiser do a 2450 mAh variety, they claim is good for 325 shots, not sure how they work that out... ), and just try to remember to charge them up, that way you will get more than 10 shots out of them next time you turn the camera on  :D.

A side note, the poster of the article may have fixed his problem for an entirely different reason. Canon cameras tend to have an issue with the springs that hold the batteries in place, as has been discussed elsewhere on this forum, as I recall. The reason he may be having more success with the 104500 is that they are sometimes a fraction longer than your average AA cell, and it, or his wooden dummy cell, might simply be making better contact with the non springy springs in his SX110.
« Last Edit: 23 / March / 2013, 18:44:48 by ahull »
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Offline waterwingz

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Re: Ultimate rechargable AA batteries for Canon camera ?
« Reply #3 on: 23 / March / 2013, 18:39:53 »
Quote from: reyalp on 23 / March / 2013, 17:39:58
The obvious hyperbole of "last for a bout 10 shots or so" doesn't inspire confidence.
True.  Although when I'm coding, testing or script writing, I find I'm constantly rotating the AA rechargables in my A1200.  Subjectively,  the G10 and SD940 batteries seem to last a lot longer per charge cycle.

Quote
Of course, actual measurements could certainly be interesting
Not sure I'm going to invest $50 for a charger and batteries to find out.  Rather spend that money on more eneloops.

Quote from: ahull on 23 / March / 2013, 17:54:58
If you want to use LiFePO4 batteries, you would be better using them through the external power adapter jack, then you can get some serious capacity batteries.
Now that's an idea I could get into.

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Offline ahull

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Re: Ultimate rechargable AA batteries for Canon camera ?
« Reply #4 on: 23 / March / 2013, 18:54:30 »
It seems the usual source of all things cheap (and often nasty) will supply you with a couple of these, 2 dummy cells and a charger for  11.08 GBP ($16.88 US), so a bit cheaper than $50.

http://www.ebay.co.uk/itm/2X-14500-600mAh-3-2V-LiFePO4-Li-ion-battery-AA-consumer-type-2X-spacer-charger-/271160549585?pt=US_Rechargeable_Batteries&hash=item3f226da0d1

You can still get quite a few AA NiMh for that money though.

Either go for the quality ones, (my preferred option) or if you want ones with 3000mAh printed on them, of unknown capacity you could try..

http://www.ebay.co.uk/itm/2-AA-2A-3000mAH-NiMH-Rechargeable-Battery-Solar-Light-/370528578507?pt=UK_ConsumerElectronics_Batteries_SM&hash=item5645396bcb

No matter what the capacity, I bet you still get more than 10 shots out of them, and they come in a variety of fetching colours.  ;)
« Last Edit: 23 / March / 2013, 18:57:59 by ahull »
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Offline ahull

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Re: Ultimate rechargable AA batteries for Canon camera ?
« Reply #5 on: 24 / March / 2013, 07:19:00 »
If you want to read a lot more on this subject, take a look at the comments on HAD.

http://hackaday.com/2013/03/23/lifepo4-batteries-work-much-better-in-a-camera-than-nimh/#idc-container
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Offline waterwingz

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Re: Ultimate rechargable AA batteries for Canon camera ?
« Reply #6 on: 24 / March / 2013, 11:01:43 »
Quote from: ahull on 24 / March / 2013, 07:19:00
If you want to read a lot more on this subject, take a look at the comments on HAD.
That's where I got the original link - it fun to see all the comments.   From what I saw, nobody posted anything like your comment about the cell being slightly longer and overcoming the battery contact spring force issue.

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Offline thepanoguy

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Re: Ultimate rechargable AA batteries for Canon camera ?
« Reply #7 on: 24 / March / 2013, 11:54:51 »
Ten years ago, the case Zapmaker makes may have been relevant. We now live in a different manufacturing era.

http://phys.org/news/2012-06-carbon-nanotube-based-ultra-low-voltage-circuits.html

http://ieeexplore.ieee.org/xpl/articleDetails.jsp?reload=true&arnumber=6229838&contentType=Journals+%26+Magazines

http://au.wiley.com/WileyCDA/WileyTitle/productCd-0780334469,miniSiteCd-IEEE2.html

Canon does not disclose the technical details of their products. If Canon states that the product is designed to work on NIMH cells, either they are using an internal on chip DC to DC circuit to boost the working voltage or they are using low voltage silicon.

The inbuilt Canon camera voltage shut down would be to protect the NIMH cells from voltage reversal rather than reaching the limitation of the silicon voltage functionality. 

http://en.wikipedia.org/wiki/Nickel%E2%80%93metal_hydride_battery

Discharging

A fully charged cell supplies an average 1.25 V/cell during discharge, down to about 1.0–1.1 V/cell (further discharge may cause permanent damage in the case of multi-cell packs, due to polarity reversal). Under a light load (0.5 ampere), the starting voltage of a freshly charged AA NiMH cell in good condition is about 1.4 volts.

Over-discharging

A complete discharge of a battery, can result in one or more cells going into polarity reversal, which can cause permanent damage to those cells. This situation can occur in the common arrangement of four AA cells in series in a digital camera, where one will be completely discharged before the others due to small differences in capacity among the cells. When this happens, the good cells will start to drive the discharged cell in reverse, which can cause permanent damage to that cell. Some cameras, GPS receivers and PDAs detect the safe end-of-discharge voltage of the series cells and auto-shutdown, but devices like flashlights and some toys do not. A single cell driving a load can't suffer from polarity reversal, because there are no other cells to reverse-charge it when it becomes discharged.

Irreversible damage from polarity reversal is a particular danger in systems, even when a low voltage threshold cutout is employed, where cells in the battery are of different temperatures. This is because the capacity of NiMH cells significantly declines as the cells are cooled. This results in a lower voltage under load of the colder cells.
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Offline waterwingz

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Re: Ultimate rechargable AA batteries for Canon camera ?
« Reply #8 on: 24 / March / 2013, 12:19:13 »
So the real question should be : Which battery takes the most images before the camera shuts down?

There are probably lots of other good questions - charge retention over time while idle comes immediately to mind.

I guess "somebody" would have to do some real life testing.  Right now I'm mostly seeing a lot of "armchair theory" work :)
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Offline ahull

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Re: Ultimate rechargable AA batteries for Canon camera ?
« Reply #9 on: 24 / March / 2013, 13:14:30 »
If you want to consider disposables, someone has done all of the hard work for you. http://www.batteryshowdown.com/  Good to see Costco, Ikea and Morrisons up near the top, I am always a bit cynical about the Premium battery  big names claims).

Otherwise I would say buy lots of the cheap NiMh ones (a 20 pack of nonames comes in under 10 GBP (here for example )) , keep them charged, and throw them out when they don't hold their charge anymore. At 0.42p per battery it almost doesn't matter what the capacity is  :blink: Anybody know of a charger that will keep 20 AA  NiMh cells topped up? I'm almost tempted to buy them  :D

Another interesting experiment would be to build a quick and easy capacity tester so you can see how far off the 3000 mAh mark those noname cells actually are.

In fact I just had a thought, we could script that on a canon P&S quite easily, the hardware is all there, the camera already knows the battery voltage, if we put the camera in a known state, we can run a set sequence from fully charged till the battery voltage is close to its cutoff point, log the results to the SD card.  Time to dust off my old A560 and ask the CHDK public to send me lots of free batteries  :xmas.
« Last Edit: 24 / March / 2013, 13:34:50 by ahull »
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