The 'High Voltage' AA cell - yet another consumer gotcha
LoopyByteloose
Posts: 12,537
Last year, I purchased a CANON SX150 Powershot as a replacement for an old digital camera that wanted $40USD for Lithium cells. It is supposed to use off-the-shelf AA cells and that was the big attraction for me.
What I have been finding is that the Canon SX150 is perceived as having a poor battery life. I try to use brand new alkaline on it and only get a few shots before a low battery reading. The same alkaline read fresh on my battery tester and run my CD player nicely for a long time.
The issue appears to be that the voltage rating is listed at 3.15 volts. It seems to me that they used a Lithium cell 3.2 volt design and just assumed that it would work with AA cells. Since the Lithium is a very flat curve, you get 3.2 volts over most of the use. But alkaline have a bigger slope. It doesn't take much to drop below 3.15 volts for two cells.
So now I am looking for alternatives. I searched 'higher voltage AA cells' and these appeared NiZ chemistry.
http://www.amazon.com/PowerGenix-PGX-4AAZiNc-1-6v-Voltage-Rechargeable-Batteries/dp/B0029LHXG2
There is some discussion of 'higher voltage AA Lithium cells' as well.
But it looks like the camera makers have not let consumers off the hook for more expensive batteries for any digital camera.
I would use one 3.2 Lithium ion AA and a dummy, but the cell is too long to fit in the camera.
What I have been finding is that the Canon SX150 is perceived as having a poor battery life. I try to use brand new alkaline on it and only get a few shots before a low battery reading. The same alkaline read fresh on my battery tester and run my CD player nicely for a long time.
The issue appears to be that the voltage rating is listed at 3.15 volts. It seems to me that they used a Lithium cell 3.2 volt design and just assumed that it would work with AA cells. Since the Lithium is a very flat curve, you get 3.2 volts over most of the use. But alkaline have a bigger slope. It doesn't take much to drop below 3.15 volts for two cells.
So now I am looking for alternatives. I searched 'higher voltage AA cells' and these appeared NiZ chemistry.
http://www.amazon.com/PowerGenix-PGX-4AAZiNc-1-6v-Voltage-Rechargeable-Batteries/dp/B0029LHXG2
There is some discussion of 'higher voltage AA Lithium cells' as well.
But it looks like the camera makers have not let consumers off the hook for more expensive batteries for any digital camera.
I would use one 3.2 Lithium ion AA and a dummy, but the cell is too long to fit in the camera.
Comments
Nickel Zinc seems the way to go, and might be handy for any old 4 cell BOEbot.
Loopy,
I purchased these exact batteries two years ago, from Amazon.
I have been using them in my BoeBOTs, Toddlers, and Scribblers with no problems. They do extend running time, although I have not measured, but I would guess by 10 to 15% over normal AA.
I bought the PowerGenix because I always use rechargeables and the Ni-CD and Ni-MH had lower charged voltages than normal Alkalines.
I would recommend the PowerGenix.
I bought some fresh Duracells that test at 1.625V. My other ones are just 1.5V or so and the camera won't accept them... though everything else will.
I also picked up some dummy AA cells to make a wall wart to camera adapter. Mostly, I want to use this as a bench camera and power from an A/C mains anyway. I have 3.3v 1 amp regulators that should do the trick.
My local professional camera shop seems to have gone out of business in the past few years.. now a vacant lot. This is the kind of thing that they used to always have.
I used the supplied charger, (same company), with no problems. One hour charge, but I would like a less aggressive charger, as 2 of my 12 cells seem to overcharge to 1.8 volts. Still, they work OK.
The charging algorithm I use is simple: Charge at 300 mA until the cell voltage reaches 1.90V. Turn off charge current for ten seconds. Charge at 100 mA until cell voltage reaches 1.90V. Done.
Some other details about the care and feeding of NiZn:
* Don't discharge too far. 1.6V is as far as I let them go.
* If they've sat for a month, they should be recharged.
If these conditions are observed, they last a long time. BTW, it seems to me that PowerGenix has stopped making/marketing NiZn. Fortunately all the NiZn cells I've ordered from China, in both AA and AAA sizes, have performed well. There are plenty of buyers to chose from. Still seems to be a thriving product despite PGs withdrawal.
I really hope this resolves the camera's annoying battery behavior. I have a dozen of so perfectly good Duracells tucked aways for other uses now that it has refused.
The camera won't let them discharge below 3.15v for the pair.
That will prove to be very handy with NiZn chemistry. It's annoying to have to check cells manually.
I had one bad experience of going to Japan on a wonderful trip and having a special Lithium ion cell fail. Nowhere on the tour route was there anything available to replace it.. so no camera. Japan has to be one of the most fun to photograph countries in Asia.
I have same camera and 2 pcs of Sony AA rechargeables (2100mah), take about 250 shots, most with flash.
My sense is it is NOT a construction defect. It is a design defect. There are lots of postings on the internet about the Canon SX150 battery problem.
It wouldn't surprise me if a problem product was dumped in Taiwan.
Your camera will require more and more power, same battery will be draining faster and faster, camera heating and then power controller will die.
Well, it is interesting that you think this will lead to an overheating failure. I have searched the internet for failure modes for the Canon SX150 and there is nothing about such. One the other hand, I have found postings that claim that Zn-Ni batteries will resolve the problem and that it is a waste of time to use alkaline AA and NiMH. The camera simply shuts down way before the battery is fully discharged.
Others claim that switching to NiMH will resolve the problem, but I don't see how a battery that produces 1.2 volts nominally will work with a 3.15volt system for more than a few moments when fully charged.
If you look at battery chemistry, the delivered voltage is an S-curve with a gentle slope in the middle region. At the fully charged end, the voltage goes way up, and at the discharge end it rapidly drops down.
The purpose of the Zn-Ni is to have that gradual slope region be at a higher delivered voltage for a longer period of time.
It seems I am just using the high-end tail of the battery's capacity. And that is a waste.
I do have some NiMH 2400ma AA cells, I will try them and see what happens... but their nominal output is 1.2 volts. That is way below what it seems I require.
They have a problem with calibrating the end points of the shut off.....
Its a Bit some where to change in there firmware ..
My S5-IS was the same way ......... good news was the cells were half dead when the cam triggerd the shutdowns . I would pop them in to the speed light I had and the strobe was not very picky about the voltage state ...... made use of them .
Some * properly* made gear has a rech/alk menu that will set the bar at the right state .
But when the battery is getting empty the phone refuses to even try and take pictures.
More than a few times this has been really annoying.
I'm mean, please try for God's sake, even it you fail and the bats are dead afterwards. I don't care just do what your owner asks!
Nothing in the documents -- they just say 'You must use Canon AA cells -- rechargeable or not. Anything else might have dire consequences"
So I loaded the camera with a pair of NiMH 2700ma cells and it is now working fine at about 2.8 volts. Go figure. It seems to be more about the available current to charge the built-in flash (can I turn that completely off?).
I really don't care what I use if the batteries work well, but I didn't buy an AA cell compatible camera to have to run back to Canon for more batteries every time I need some.