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Old Dec 7, 2006, 2:26 PM   #1
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i just bought an energizer 15 min charger and the instruction said that when the battery has finished charging, green light comes on and the fan stops. but my fan does not stop after green light comes on but stays on another 10 minutes. is something wrong with my charger?

also i read somewhere that this charger only charges the cells up to 85% when the green light comes on. if you leave the batteries in for a few more hours it will trickle charge up to maximum capacity. is that true? does not say anything of that sort on the piece of cardboard instruction that came with it. i really wishenergizer include a bit more info with their products.

thanks for helping
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Old Dec 7, 2006, 3:17 PM   #2
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I just scrapped my Energizer 15 minute charger and batteries for Sanyo Eneloops. The batteries had faster self discharge rates after about 4 months of using the charger. I had them carefully labeled, never mixing capacities, but I believe the charger actually dimished performance, as I was satisfied before switching. The charger recently died, and I'm happy to be rid of it. Hopefully, things will go better for you.
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Old Dec 7, 2006, 9:30 PM   #3
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I have had the Energizer 15 minute charger for about a year. I got a great deal on it (charger and four batteries were only about $14 when it was on sale, and I had a $5 coupon as well), and it has performed flawlessly for me. The fan does stay on for 10-15 minutes after the green light illuminates. I have been leaving the batteries in until the fan goes off. My camera (Canon A520 uses 2 AA's) does not show the battery strength meter until the batteries start to get low. but I have never had the low battery indication come on for me. I have used the camera on and off for most of the day on a couple of occasions, and never had to use the other pair of cells. MY son uses my old Panasonic, which can display the battery strength meter at all times if you want, and on the occasions when he has borrowed a couple of batteries from me, he has used that camera all day and never had the meter go below about half power.



All in all, I am happy with the perforamnce of the charger and batteries. When they eventually die, I'll probably replace them with Eneloops because their price is starting to come down as well. I expect to get a couple more years' service out of the Energizers, based on how well they have lasted so far.
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Old Dec 8, 2006, 12:10 PM   #4
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thanks propwash. at least i know my charger isn't faulty cos the fan satys on 10 minutes or so
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Old Dec 8, 2006, 4:34 PM   #5
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Hello GG,

The Energizer (and Duracell) 15 minute charger is the leading edge of NiMh charging. There are more safety features and advanced technology in them that allow you to charge cells fast.

You can get a more complete charge with a slower charger, however the Energizer does get the cells about 97% of full capacity. It is normal for the fan to continue to run after the green light comes on. It seems there are actually 3 charging stages. The first one runs at around 7.5 amps until the light goes out. This is followed by a short time at roughly 3.5 amps, then the charger goes into a trickle charge for 24 hours. You can leave your cells on the charger overnight to pick up the last 3%, if you want to.

These chargers are picky about the cells they charge. If you cell has developed higher internal resistance, the charger will reject them. If just so happens that "marginal" cells don't perform that well, so perhaps this is a "feature..."

The down side is that fast charging is hard on cells. With 14 hour charging, you can expect to get around the battery manufacturers claim of 600 - 1000 cycles. When you move up to 1 - 2 hour charging, the number of cycles drops to around 300 - 500 cycles. When using the 15 minute chargers, the cycle life drops to around 125 - 150 cycles. Please note that this cycle life with the 15 minute chargers is not a speculation, but has been actually measured and tested.

Very fast charging is harder on high capacity cells (2500 mAh and higher). The mid range or lower capacity cells seem to do better with it (2000 mAh and below).

The up side of 15 minute charging is that in the time it takes to enjoy a cup of coffee or have a bathroom break, you end up with 97% charged cells and are ready to go.

Tom
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Old Apr 8, 2008, 10:23 PM   #6
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hi,
i bought an energizer 15 mins charger and 4 batteries (AA 2200 mah).i got it from the US so i had to buy a voltage converter(110V ac to 220V ac).i thought this would work as i have been using the same type of convertor for other gadgets i got from US.but when the charger is plugged in with more than one battery in it for charging,but the light goes from red to green and back instead of staying on red constantly(which indicates charging).this repeats as long as i keep it plugged.even with only one battery in the charger this is happening.
i dont know why this is happening.is this the way it charges or is it malfunctioning? anybody has any idea pls do post here.if it is some problem with the charger then i think ill have to buy one locally.
thnx
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Old Apr 19, 2008, 9:53 PM   #7
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Hello Helboy,

You may be running up against the limits of your converter.

The charger runs at around 85 watts. What is your converter rated for?

Tom
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Old Jul 2, 2008, 5:36 AM   #8
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SilverFoxCPF wrote
Quote:

The down side is that fast charging is hard on cells. With 14 hour charging, you can expect to get around the battery manufacturers claim of 600 - 1000 cycles. When you move up to 1 - 2 hour charging, the number of cycles drops to around 300 - 500 cycles. When using the 15 minute chargers, the cycle life drops to around 125 - 150 cycles. Please note that this cycle life with the 15 minute chargers is not a speculation, but has been actually measured and tested.
What are the rejection criteria?

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Old Jul 10, 2008, 9:30 PM   #9
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Hello Itsme,

As far as I have been able to measure, the 15 minute chargers reject cells when their internal resistance gets to around 0.1 ohms.

Tom
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Old Jul 12, 2008, 12:12 AM   #10
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The problem with fast charging of most batteries is that the faster (shorter charging time) the charging time the hotter the batteries get. that why you will see 15 minutes to 1 hour chargers with coolingfans. The best compromise is to use a 4 hour charger. The reason the energizer rejects the high resistance batteries is that they might catch fire. BTW the fan will run until the batteries are cool and then shut off for the trickle charge.
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