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Old 04-15-2006, 01:42 PM   #1
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Default Overcharging with a peak charger?

I have a Novak peak charger and just acquired some used 3800 intellect packs of 6 cells. When I charge them at 5mv/cell peak they take around 4800 mah of charge at 5 amps to peak. At that point they are around 100 degree F, just warm to the touch. Is this acceptable or a problem? Should I lower the 5mv/cell until they only charge to 3800 mah?
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Old 04-15-2006, 01:46 PM   #2
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Cells will often take more than their stated capacity in a charge. The extra energy is lost as heat. So long as the cells are not overheating, no damage is being done.
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Old 04-15-2006, 03:30 PM   #3
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100F that's cold they say they like to peak at around 125F
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Old 04-16-2006, 11:52 AM   #4
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Thanks for the information. The instructions with the charger don't really give you the whole story. For instance, while you have to enter the mah of the cell capacity, since its a peak charger and shuts off based on delta peak mv, what does it do with the fact you told it the pack is a 3800 or a 1500 mah? Why would it care about mah if it stops charging based on peaking? Or whether you tell it nicd or nimh since you specificed the peak voltage change? Does that change the charging method somehow?

And when a pack is rated at 3800 mah, does that mean it can deliver 3800 mah output, or that you charge it with 3800 mah? I'd assume its the former, not the latter. Anyone care to comment on the kind of usefull life they get out of a pack. Do you discard them or relegate them to practice packs when they get down to what condition? A certain drop off in capacity or voltage?

Anyhow, the new 3800's are sure a heck of a lot more powerfull than my made in china 3200 stick packs. The run longer and stronger.
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Old 04-16-2006, 11:52 AM   #5
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Quote:
Originally Posted by Superkarter
100F that's cold they say they like to peak at around 125F
Ok, but I am just kind of guestimating based on touch.
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Old 04-16-2006, 12:08 PM   #6
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If your pack is hot after a session of racing and heat is the enemy then they should never be that hot after a charge. U cannot avoid the battery getting HOT during a race but U do not want to charge them until they are that hot. This should give U a FEEL of how hot NOT to let them get.
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Old 04-16-2006, 06:58 PM   #7
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Default Question.

Please correct me if I am wrong,
You attach 5 amps to a 6 cell battery. Monitor the battery with avoltmeter and a thermometer, at some point the voltage on the meter will stop increasing and you will see a sudden spike up in temperature. When that temp hits around 115-120 F, STOP because it is fully charged.

basically what you are buying with an expensive charger is a circuit to do this automatically.
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Old 04-16-2006, 10:50 PM   #8
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Old Schrool is, while monitoring with a volt meter, the peak detector would count how many 100th of a volt the battery drops at the end of a charge. So when the voltage stops rising, U should be watching it carefully to see the second digit behind the decimal. It will start to decrease the charging voltage by 100th of a volt. Newer chargers allow U to set this rate but it usually drops by .04 volts for NiMh batts. and .06-.07 volts for NiCds.
I never checked the temp so I don't know about that but a guru recently told me that 135 degrees was fine. U need to know, as U are monitoring the temp, if U stop at 120 degrees it will probably still rise after U disconnect because the heat is generated form the core and takes time to reach the outside of a battery. I also don't know how much the temp will rise after the charge so be careful.
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Old 04-16-2006, 10:57 PM   #9
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Quote:
Originally Posted by Iceracer
I have a Novak peak charger and just acquired some used 3800 intellect packs of 6 cells. When I charge them at 5mv/cell peak they take around 4800 mah of charge at 5 amps to peak. At that point they are around 100 degree F, just warm to the touch. Is this acceptable or a problem? Should I lower the 5mv/cell until they only charge to 3800 mah?
for 3800's you can go to 3mv (.03) and make sure they DON'T got pas 125-130 Degrees F. I actually never try and go past 44 celcius which is about 110 Faren because when you stop, it keeps going up for a couple degrees. Most people like Promatch say, dont go past 130, id stop a bit before.

=)
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Old 04-19-2006, 03:55 PM   #10
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Default My understanding is

You can use any of the quality older Nicad chargers to charge any NIMH battery as long as you are not depending on the automatic circuitry/program to stop the charging process. If you are going to be there monitoring the charging with a voltmeter and thermometer.

Obviously a real NIMH charger with a 5 amp output is better, and using a NICAD charger can cause problems if you forget about it and aren't there when the pack peaks. My experience has been that the NICAD charger actually shuts down early rather than late but from what I read that can not be depended on.
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