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6.0v Nimh battery

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Old 09-05-2010, 12:14 AM
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James c harrell
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Default 6.0v Nimh battery

I have a 6v Nimh battery in one of my planes for the reciever. Recently it was dead when I went to the plane and I re-charged it. I am a little worried about it and want to cycle it to see just how many amps it can or will store,hold. I have a Triton charger but the instructions say that Nimh batteries require no cycling. Later in the instructions it says that the discharge rate for Tx/Rx is 1.1 volt per cell. To find out if the battery is good, what rate should I use? Should I charge it and wait a day or so before dis-charge? What procedure is the best to follow?
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Old 09-05-2010, 12:51 AM
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Default RE: 6.0v Nimh battery

Does your charger tell you how many mAh's it put in the battery?

If it does, plug it into a receiver and turn it on to drain it all the way down, charge it back up and log how much it takes. Repeat and check the numbers.

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Old 09-05-2010, 09:37 AM
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Default RE: 6.0v Nimh battery

James,
Discharging is for exactly the purpose you want.
Discharge the battery at .3C to .5C to .9 volts per cell - 4.5 volts.
Then recharge the battery at .1C until it peaks.
If your battery is not at > 80% of capacity repeat the process.

NiMhs discharges at a high rate, up to 5% per day.
If they sit to long they need to be reformed, charged for 16 hrs @ .1C.
The Triton is not good at this but repeated cycling will accomplish the same thing.
This may take up to 6 to 10 cycles.
If you still don't have > 80% of rated capacity it is time to discard the battery.

Good Luck,
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Old 09-05-2010, 10:15 AM
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Rodney
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Default RE: 6.0v Nimh battery

Measuring how much you put into a battery during charge (for Nixx type batteries) does not tell you a lot. You must always put quite a bit more in than you can take out due to the inefficiencies of the charging process. What you measure is "how many mah you can take out) after a full charge if you want the true facts. To compare to factory specs, you need to discharge at about 0.3C down to 0.9 volts/cell. Most modern chargers are set up to let you do this as they record the amount of energy you remove from the battery at a know rate.
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Old 09-05-2010, 11:36 AM
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James c harrell
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Default RE: 6.0v Nimh battery

KW, When you say.3C to .5C do you mean for me to set the discharge rate at .3 to .5 A, with a cut off point at 4.5 volts. That is what I have heard with the voltage but the manual on the Triton says to use 1.1 V per cell for Tx/Rx batteries. I didn't have any idea what amperage to use. When I used the 1.1 V per cell as a cut-off point I could only get 786 back out of it and it is supposed to be a 1600 mah battery. When I use your settings I hope to get better results!!
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Old 09-05-2010, 09:52 PM
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Default RE: 6.0v Nimh battery

Discharging to .9 volts per cell at .3 amps will give you an idea of the maximum output and health of the battery. As stated above it should be 80% or better of the rated capacity.Nobody would intentionally run a battery down to .9 volts per cell while flying a plane so those numbers are for battery condition reference only.
Discharging to 1.1 volts per cell will give you an idea of how much real life usage the battery contains.
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Old 09-06-2010, 08:42 AM
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Default RE: 6.0v Nimh battery

James,

.3C stands for 30% of the Capacity of the battery.
In your case, .3 * 1600 = 480 mAh or rounded up to 500.

When discharging I go to .9 volts per cell.
This fully discharges the battery and gives a better indication of what is happening.

When flying I stop at 1.1 volts per cell.

Here is a great website to learn more about batteries.
http://www.hangtimes.com/redsbatteryclinic.html

Good Luck,
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