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Old Nov 1, 2006, 6:09 AM   #1
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I am using the GPPB01 charger by Gold Peak which has a rating of 2100mAh. It is a
1 hour charger with a charge rating of 2100mAh. While charging, the LEDs are on but after 1 hour, the LEDs turn off. Does this mean that after 1 hour it shifts to trickle charge (of unknown charge rate)?

Assuming my batteries are 2500mAh , how would I charge them to full capacity? Would it be by trickle charge or by letting the batteries cool off then recharging them a second time?



Thank you in advance.
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Old Nov 1, 2006, 7:25 AM   #2
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A charger does not measure mAH to determine full charge. That determination is done other ways. Unless your charger is a timed-only charger, it is "filling" your battery to the 2500 mAH, or whatevercapacity your battery will accept based on its age.
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Old Nov 1, 2006, 7:27 AM   #3
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If it turns off after 1 hour, it sounds like it is a timed charger. So unplug it and then plug it back in again. Now it should continue charging (by unplugging, you have reset the timer).

Now whether the charger can measure the charge level of your batteries and turn off when full, I don't know. But I doubt it. So you would need to manually unplug it to stop the charging process.

Your 2500 mAh batteries are 400 mAh bigger than the 2100 mAh batteries the charger is designed for. That is about 1/5 of the 2100 capacity, so I would unplug the charger in 1/5 of an hour, or about 12 minutes.

Better yet. Just go out and buy an intelligent charger that will work properly with 2500 (and larger) mAh batteries.
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Old Nov 1, 2006, 7:40 AM   #4
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The product spec sheet at http://www.gpbatteries.com/pdf/PB01_DS.pdfindicates it is a safety timer only, NOT a timed charger, and shuts of after 1 hour and 25 minutes.

If it indicates full charge at one hour by the appropriate led lighiting, then the 2500mha battery is as full as it will get.

Personally, I usesmart chargers and have no doubts as to the charge condition of my batteries.
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Old Nov 1, 2006, 9:37 AM   #5
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Hello Al,

According to the specification sheet, your charger charges AA cells at 1600 mA for just under 1.5 hours.

Let's do some math...

A completely drained 2500 mAh cell charged at roughly 0.5C will require around 10-15% more charge than its capacity. The charge process is not 100% efficient and some of the charge goes to heat. Faster charge rates are more efficient than slower ones, and you are somewhere in the middle with this charger.

Using a 10% overcharge value, we have 2500mAh * 1.1 = 2750 mAh required to fully charge your cells. The charger is capable of 1600ma * 1.42h = 2272 mAh. You are going to end up 478 mAh (or a little over 17%) short.

It looks like you need around an extra 18 minutes to get a full charge.

The work around is to start charging and set a timer for 30 minutes. At the end of the 30 minutes, unplug the charger and start the charge again. This will allow for some trickle charge and you should end up with fully charged cells.

Tom
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Old Nov 1, 2006, 11:31 AM   #6
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SilverFoxCPF, you are assuming a completely dead battery, which most are not and whichwould give fits to many chargers if the batteries were totally dead.

If his unit indicates a full charge at one hour, the safety timer did not kick in.The batteryis as charged as it will get.
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Old Nov 1, 2006, 9:43 PM   #7
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Hello Hgernhardtjr,

I thought it was a pretty safe assumption...

In my "neighborhood" we use our batteries until the low battery indicator comes on. This indicates that the batteries are dead. Chargers are designed to charge these completely dead batteries and do so without problems.

Please understand that after a 2500 mAh battery has been completely drained, its open circuit voltage will still be at around 1.18 volts. I believe you may have been thinking of a cell that has been drained and then left connected until its voltage drops to 0 volts, and stays there. Chargers do not like these cells, however completely drained cells are no problem.

Tom
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Old Nov 2, 2006, 5:59 AM   #8
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Thank you everyone for your input. The spec sheet provided by Hgernhardtjr shows that my charger would fully charge a 1600mAh battery in 1 hr.

My option I guess to fully charge the batteries would be to charge it until the light goes out ~1 hour for 1600mAh charge then removing the batteries and charging for an additional 38 minutes to top it off to 2500mAh. Pretty much what Tom computed.

At least now I know what to do.

Thanks guys!

Al
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Old Nov 2, 2006, 11:13 AM   #9
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Yeppers ... stick that gas nozzle into the car with the 25 gallon tank. When it clicks off at 16 gallons because the tank is full, stick it back in and fill it some more ... be sure to keep triggering the nozzle until the pump reads 25 gallons (pumps around here stop pumping at $50, though).:?
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Old Nov 8, 2006, 11:21 AM   #10
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SilverFoxCPF wrote:
Quote:
It looks like you need around an extra 18 minutes to get a full charge.
Make sure that you the first charge cycle is 18 minutes. Switch off the charger after 18 minutes, the back on for the times duration of 1 hour.

That way, if you forget the switch off in the first 18 minutes, the batteries will charge for an hour and be slightly undercharged.

If you were to do the 18 minutes as the 2nd charge, then if you forgot, the batteries would be 'cooked'.
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