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Old Aug 22, 2006, 7:53 PM   #1
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Does anyone know if the Sony BCG-34HE4 Super-Quick Worldwide Battery Charger (cheap/well reviewed at Amazon) apparently a "smart charger", is smart enough to give a full charge to these 2650 mAh AA batteries, or their 1000 mAh AAA little brothers?

Thanks,
Rich
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Old Aug 23, 2006, 3:47 PM   #2
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Hello Rich,

It is hard to say for sure...

It has a timer shut off, but I can't find what the time limit is. If it is 6 hours, for 4 cells, or 3 hours for 2 cells, it should charge the 2650 cells. If it is set less than that, it will not fully charge a fully discharge cell on 1 cycle. You can always unplug the charger and plug it back in to reset the timer.

Tom
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Old Aug 23, 2006, 5:30 PM   #3
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Thanks for responding. So let's say the timer is too short - then I unplug and replug. Will it then shut off after only 10min or however long it takes to finish topping off the battery, due to its "intelligent" voltage monitoring?
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Old Aug 23, 2006, 11:03 PM   #4
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Hello Rich,

NiMh cells do not have a large end of charge signal. At low charge rates it is possible for the charger to miss it and end up cooking the cells. It is usually recommended to charge at a minimum of 0.5C in order to get a good end of charge signal.

You are considering the 2650 mAh cells, so 0.5C would be 1325 mA.

The charger uses 500 + mA when charging 4 cells and 1000 + mA when charging 2 cells. The 500 mA rate is a little low. If you want to be sure, think of this charger as a 2 cell charger and charge in slots 1 and 4. The 1000+ mA rate is a little low, but should work.

Back to your question...

New NiMh cells can be difficult to properly charge the first couple of times. After that they settle down and charge properly. You may not have any problems during the second charge cycle, but it is always best to monitor the cell temperature during charging. If you put your fingers on the cell, it may feel warm (around 120 F), however if it feels like a baked potato coming out of the oven (around 140 F or higher) you should shut things down and remove the cells from the charger regardless of whether the charger thinks it has finished the charge or not.

Keep in mind that NiMh cells heat up at the end of the charge, and that heat destroys NiMh chemistry. We are walking a little bit of a fine line here. We want the most capacity we can get into the cell, but this causes the cell to heat up. The better we are at balancing, the longer the cells will last with regard to cycle life.

The intelligent voltage monitoring may properly terminate the charge, but you should keep an eye (or rather a finger...) on it to make sure your cells don't get hot.

Tom
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Old Jun 25, 2008, 10:25 AM   #5
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The thread is old.. but I found that Duracell's value charger and Energizer economy charger gets the best capacity into these cells.

The Duracell economy charger charges for 6.5 hours at 360mA, then indefinitely at 100mA thereafter and if you leave it plugged in for about 14-16 hours you get the full capacity.

The Energizer charges for 8.5 hours at 360mA and shuts off and you get very slightly less than full.

These are probably the gentlest chargers on the cell when you charge completely emptied cells, however they're only controlled by a timer, so partially discharged cells are not going to suffer overcharging and reduced life.

I'd go with the new Energizer ACDC since it can charge 1-4 cells independently and I think it's only $10 or so.


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Old Jun 25, 2008, 10:28 PM   #6
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I use 2 chargers an olympus battery charger that c ame with my Oluyumpus C-740 years ago and a newer energizer bettery charger I got at Krogers. Both will charge my energerizer 2600mha and my 2900mha impact brand batteries. The color o f the indicator light will change when the batteries are fully charged. Do not shut off just runs on a trickle charge from there out till you unplug the charger. Never had an issue with either charger.

dave
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Old Jun 28, 2008, 4:40 AM   #7
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Photo 5 wrote:
Quote:
I use 2 chargers an olympus battery charger that c ame with my Oluyumpus C-740 years ago and a newer energizer bettery charger I got at Krogers. Both will charge my energerizer 2600mha and my 2900mha impact brand batteries. The color o f the indicator light will change when the batteries are fully charged. Do not shut off just runs on a trickle charge from there out till you unplug the charger. Never had an issue with either charger.

dave
Chargers are usually designed around batteries available at the time. A charger designed when 2100mAh was the highest capacity available and rated for 1 hour charging is designed to charge 2100mAh batteries in an hour with some room for expansion, but safety shut-off timer turning the charger off before fully charged on new 2650mAh cells.

Just because the indicator turns green doesn't mean the battery is fully charged. If the batteries were not fully discharged before charging, you might get a full charge, but you likely can't fully charge a fully drained 2650mAh batteries completely on many chargers.

I test my chargers capability by discharging the charged cells on Maha MH-C9000, which is basically like draining your gas tank into buckets and literally measuring how much gas is inside, but unlike gas, you can't weight it or use a gauge.

There is no accurate way of measuring how much mAh the battery actually retains without fully discharging down to 1.0 or 0.9v and seeing the actual charge removed.
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