NiMh battery problems!

[spoolin01]

I bought a refurbished Canon A720IS a couple years ago, and had the same problem with NiMH batteries, maybe 6 shots before the low battery indication. I did check the firmware issue, but don't recall if that applied to this particular model. I even returned it and got another that acted the same. At Canon's suggestion, I bought the really expensive Canon batteries and indeed they seemed to work better, though I dumped the camera before cycling the batteries more than once. There does seem to be a fair incidence of premature decline in individual NiMH batteries (I've used Kodak, Sanyo, Sony, Maha, Powerex, GB, and others) but it's not so high that it should be impossible to find 2 or 4 batteries that will make a camera work. I suspect the problem is the battery sensing logic that Canon uses, or maybe QC problems at times with their components. The 'bad' batteries were perfectly good and matched, both in voltage and capacity, using a LaCrosse BC-900 for testing. I use them regularly in strobes and other applications without problem, they last well. Interestingly with the 720IS, alkaline batteries, even though they were higher nominal voltage, also didn't work for long at all. Maybe the camera uses a rate of change evaluation rather than simple voltage... Or maybe they put too much drain on 2 batteries at times. It's an odd situation...

 

[emoreira]

I also bought a Canon A570is and started to use my previously bought NiMh batteries with poor results.
I posted this here and Mr. Nemrod recommended me to switch to Sanyo Eneloop batteries, in general Precharged-rechargeable batteries.
No more worries to get the flashing low bat sign in the camera display.
I highly recommend those batteries and a special thanks to Nemrod again.

 

[bvanant]

This gets curiouser and curiouser. It would appear that the Canon battery check circuitry isn't simply looking at the voltage but rather something more complex. Time to buy a used 570 and take it apart.
Bill

 

[Nemrod]

This gets curiouser and curiouser. It would appear that the Canon battery check circuitry isn't simply looking at the voltage but rather something more complex. Time to buy a used 570 and take it apart.
Bill

Please do, I would be curious what you find. It is not just the 570 but several of the Canon P&S cameras including the 720/740 and 590 will do the same thing. Using the Eneloop or Duracell "Pre-Charged" type cells the issue goes away and the cameras work fine, could not be better. But the minute I try another type battery other than the pre-charged types the voltage flag returns and even the mighty Duracell Copper Top alkaline cells drop out right away.

I don't think it is so complicated, the high cap cells have more amperage output (capacity) but they drop below the warning trigger voltage sooner, but it would be nice to see what is going on, what the program really looks at. A 570 can be had often on Ebay for not much, especially the used and abused ones, to experiment with.

N

 

[Nemrod]

I also bought a Canon A570is and started to use my previously bought NiMh batteries with poor results.
I posted this here and Mr. Nemrod recommended me to switch to Sanyo Eneloop batteries, in general Precharged-rechargeable batteries.
No more worries to get the flashing low bat sign in the camera display.
I highly recommend those batteries and a special thanks to Nemrod again.

I cannot take credit, somebody else turned me on to them and just as for you my problems went away. Glad to hear they worked for you also, I knew they would.

N

 

[bvanant]

Please do, I would be curious what you find. It is not just the 570 but several of the Canon P&S cameras including the 720/740 and 590 will do the same thing. Using the Eneloop or Duracell "Pre-Charged" type cells the issue goes away and the cameras work fine, could not be better. But the minute I try another type battery other than the pre-charged types the voltage flag returns and even the mighty Duracell Copper Top alkaline cells drop out right away.

I don't think it is so complicated, the high cap cells have more amperage output (capacity) but they drop below the warning trigger voltage sooner, but it would be nice to see what is going on, what the program really looks at. A 570 can be had often on Ebay for not much, especially the used and abused ones, to experiment with.

N

I am bidding on one now, I'll let you know. My guess though is that it isn't simply the voltage. Can you tell me how long approximately does a set of eneloops last? It would make a lot of sense if a fully charged set of standard NiMH didn't last as long but the fact that they fail right after charging them up is really difficult to understand. A good question for Chuck Westfall.

Bill

 

[Nemrod]

Well, I have never shot until they (they being eneloops and Duracells) died, usually I run out of strobe go power first (Inon D2000 with eneloops). I have made two and three dives and shot until I had to come up. I turn my camera strobe to 1/3 power and other optimized settings.

Thing is that I do not get through dive number one with standard high cap NiMH batteries before getting the dreaded low voltage trigger and sometimes as soon as I turn it on and cycle it a few times.

Hey, I will toss you twenty bucks towards the camera or batteries if you really are going to take it apart and probably render is "destroyed" for all time. Send me a Pay Pal address to my PM.

N

 

[davelew]

I wonder if the temperature has anything to do with the NiMH failures?

Standard NiMH batteries get a lot hotter than Eneloops because stadnard batteries have a higher parasitic resistance. I think Inon recommends only using Eneloops in some of their strobes because of the lower heating of the Eneloops.

Since resistance usually goes up with temperature, I wonder if there is a resistor in the voltage detection circuit that has a high thermal coefficient, and so gives you a low voltage reading when the camera gets warm.

 

[bvanant]

No need, the kids in the lab need something to do anyway and we have lots of cool toys. In NiMH batteries in general, the discharge voltage goes up with temp (at least the midpoint of the flat part of the curve) so that would not suggest a reason for failure, but V does go down with temperature. One question, does the camera work on land with NiMH batteries but not in the housing underwater or is it the same problem on land as well? On some of the other digital camera boards, some folks suggest that the problem is really a design of the contacts problem and can be solved by judicious placement of some wedges or toothpicks.

From the web
"My experience with the 570IS might be helpful. When no amount of new batteries would work on the year old 570, and the Canon tech used the dreaded phrase, ''mechanical problem, return to factory'', I decided to try a worn nail file on the door contacts. Camera fired right up and continued to work after many consecutive flash shots. IMHO the very tiny pinpoint door contacts overheat and oxidize due to high current density. You said you cleaned the battery contacts, but I believe only the door contacts are important here. Be gentle with the filing, we might be doing this many times in the life of our cameras." YMMV

IF all this is true, it might be that the ENELOOP batteries have a significantly different shape on the + terminal that makes better contact with the battery door.

IN any case, I will get the camera I hope late next week and will play around with it when it comes.

Bill

 

[Nemrod]

I hope you get to the bottom of this. It will be fun anyways. I look forward to seeing what you come up with.

Nonetheless, cleaning contacts etc, if one battery works without cleaning contacts and the other doesn't work as well there is an indication that one is marginal. Besides, I clean the contacts with an eraser. I would as soon use a battery that does not require filing the contact points or other extraordinary measures.

N