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Old Oct 18, 2005, 12:32 PM   #11
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dekelsey61 wrote:
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Hi SilverFoxCPF, I have the same type of problem. I have the Energizer 2500MAh AA batteries. I left them in the charger to do the trickle charge for about 10 hours after they were done with the charge. The volts measured 1.36-1.34V. A day later, I put the same batteries back into the charger and when they were done I took them out shortly after they went into the trickle charge. The measured 1.46-1.48V. These batteries have had a history after 2 weeks on the shelf going down to .095V. I am using the new Maha C801D charger.

If a battery falls below 1.20v does that mean they are going bad? Or already bad?

Can the batteries on the trickle charge for that long of a time discharge down to the 1.35V thatI was showing?

Should a good battery ever go below the 1.20V?

What would you consider to be a fast discharge rate in time and in Volts?

Thank you for taking the time toreply to these questions.

Dan
Hello Dan,

First of all, a battery that drops from 1.4 volts to 0.09 volts in 2 weeks is bad.

After about a month, my cells drop to about 1.3 volts. I have found that the self discharge rate varies for different brands, but is usually under 1% of the remaining capacity (please note that remaining capacity does not necessarily equal voltage) per day. Hot off the charger, cells will rapidly bleed off the surface charge, but after the first hours, the self discharge rate settles down.

NiMh batteries after a year of storage will still show 1.0 - 1.2volts, but their capacity will have dropped to about 5% of the original capacity.

Trickle charging usually keeps the batteries at around 1.4 volts. If the self discharge rate is higher than the trickle charge rate, you will see a drop in voltage. A high self discharge rate usually means the cells are damaged and should be replaced.

Tom
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Old Oct 18, 2005, 12:40 PM   #12
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Hello Archish,

Let's keep the test going for a few more days. 1.3 volts seems low, but if they stabilize at that level, they may be OK.

On the other hand, if the voltage continues to drop over the next 2 days, it would appear that your batteries are bad.

As CCWKen has pointed out, you may need to do a few cycles to get them up to maximum capacity, but they should hold voltage even if they are at reduced capacity.

Please note that the self discharge rates increase with higher temperatures. Batteries stored at 100 F show a lot higher discharge rate than when stored at 70 F or lower. Are you having hot weather?

Tom
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Old Oct 18, 2005, 2:27 PM   #13
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did a complete discharge cycle and now charging it again. As for the temperature its usually arnd 35 degrees Celcius
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Old Nov 9, 2005, 10:31 AM   #14
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I also have Sanya 2500mAH batteries and I charge them with one local charger. It takes me about 24 hours to charge all 4 batteries. But the problem is that they get discharged very fast. It gives me 150+ shots but if I keep it for a day it gets drained off...

I guess the problem is with the charger itself. It is not charging the batteries 100%. The pack of charger mentions that it can charge upto 2200mAH.
Any clues???
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Old Nov 10, 2005, 8:11 AM   #15
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who_am_i wrote:
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I also have Sanya 2500mAH batteries and I charge them with one local charger. It takes me about 24 hours to charge all 4 batteries. But the problem is that they get discharged very fast. It gives me 150+ shots but if I keep it for a day it gets drained off...

I guess the problem is with the charger itself. It is not charging the batteries 100%. The pack of charger mentions that it can charge upto 2200mAH.
Any clues???

If it say that it can charge up to 2200mH, you can charge battery larger than that, only you need to charge it longer. 2500 is 113 % of 2200, so lets say the charger can fully charge a 2200 battery in 12 hours just multiply 12 hours by 1.13 (113%) , in this case 13.6 hours. At this time the 2500 will recieve 100 %. You can apply the formula to batteries with differnent capacity.




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Old Nov 10, 2005, 12:03 PM   #16
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Hello Juandelacruz,

In theory you are correct... however, some of these chargers have a timer that actually shuts the charger off after a period of time.

The way to get around that is to unplug, then plug back in the charger about half way through the charge cycle.

Tom
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Old Nov 13, 2005, 9:03 AM   #17
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We have similar complaints about the Sanyo 2500mAh back home (Malaysia). (I was googling for confirmation of this problem when I found this thread on this excellent site.). Looks like we are not alone. I thought that I should share this with you...

http://www.photomalaysia.com/forums/...ead.php?t=6911

http://forums.clubsnap.org/showthread.php?t=157107









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Old Dec 4, 2005, 2:33 AM   #18
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ok try this most chargers charges batterys to 122% of cappacty.so that means a 1000 mah battery you charge a battery to 1220 beecause of heat loss.so if you have a charger that said 35mah non timed charger it would take 34.86 hr to charge the battery to max.also if you dont wont to keep your battery on a charger 24 hr a day do a timer on a trickle type charger and say its a 35mah model do some math of 1/2 to 1 percent per day lossso we will say 3/4% per day so 1000 x .75% = 7.5 mah a day so ever 4 dayswith 4 battery in the trickle charger turn it on for 1 hr on the down side is you will need a 20 dollar timer and for a larger set up you need the timer to turn on the plug strip. but also you could do a 7 dollar timmer but they are not ase accurate. if your cammery needs aa batterys look at the battery shootout i like energizer 2500mah with a lacross bc900 or a nexcell model 50 the few dollars you save on off brands can cause problems with interinal resistance problems that will not dump the charge fast enought to cycle your camera and give you false low battery bs. keep in mine you still have this problem on matched battery from time to time my fluke 87 help me with this put it not something you need to buy if they start failling just put them in your flash light or remote ? remote whoo wonts to change batterys ever 90 days because od the discharge rate:-)
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Old Dec 5, 2005, 6:15 AM   #19
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rae1969 wrote:
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We have similar complaints about the Sanyo 2500mAh back home (Malaysia). (I was googling for confirmation of this problem when I found this thread on this excellent site.). Looks like we are not alone. I thought that I should share this with you...

http://www.photomalaysia.com/forums/...ead.php?t=6911

http://forums.clubsnap.org/showthread.php?t=157107








After reading these treads there really seem to be a problem with certain batches of 2500 mAh cells. I use 8 industrial grade cells, never had a problem
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