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Old Jan 13, 2007, 08:25 PM
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Huntsville, Texas USA
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Do you need to cycle NiMh batteries?

I've heard conflicting stories. What's the real deal?
Thanks!
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Old Jan 13, 2007, 08:47 PM
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Haralson County GA. USA
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The real deal it depends on the batteries and thier useage.
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Old Jan 13, 2007, 09:12 PM
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If mine seem weak I cycle em 2 or 3 times at a low setting. 1/2c or less. It seems to help
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Old Jan 14, 2007, 02:14 AM
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The BA
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What about brand new? I've been told to cycle the batteries 10 times before using for the first time.
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Old Jan 14, 2007, 03:29 AM
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No need for cycling but it is not a bad idea for the first few charges to be at a slow rate around C/10. You can still charge then fly, just don't fast charge immediately.

Even that is not strictly necessary. I have NiMH batteries which were fast charged from day 1, have never been cycled and are still going well 4-5 years later. As "everydayflyer" says it depends on exactly what batteries you have.

Steve
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Old Jan 14, 2007, 05:47 AM
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... on the other hand, my GP3300s would not take a charge initially (at 1C) until I gave them a 1/10C 12-hour charge. Maybe 1/2C would have worked also, but 1/10C is what I used and it worked.

Depends on make and model, as the others have said.
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Old Jan 14, 2007, 06:29 AM
Joined Jan 2004
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The main purpose of cycling a battery is to know the capacity of the pack. As the pack ages the internals break down and capacity is lost.

New cells should be cycled AFTER a formation charge is completed. A formation charge is a C/10 (capacity/10) for 18-22 hours. The initial charge does need to be longer than the normal 15 hour time frame.

How many cycles? That is an easy question. As many as it takes to get to the rated capacity of the cell. Most packs will reach rated capacity in just 1 cycle, but I have had to do it myself as many as 3 times.

Why so many times? Depends on the age of the battery. Nicad and Nimh cells typically have a shelf life of 3 years in a factory set discharged state. The older the cells, multiple cycles may need to be done. Also, should you need to do multiple cycles, each charge should be a 15 hours C/10 charge.

How often should you cycle the pack? Once a pack is proven to be at rated capacity, cycling only needs to be done to check the capacity of the pack. 1-2 times a year is all that is needed. Once a pack is at 80% of the actual initial capacity, the pack should be properly discarded. Since battery packs are very inexpensive, I replace mine every 2 years. While Nicads have been known to last more than 5 years, it is cheap insurance.

Why do some packs never get to rated capacity? It may not be the packs fault. When you cycle, you need to ensure that the cut off voltage of the cycler is not too high or too low. .8V or .9V per cell is what you want the cut off to be. If it is higher than .9V per cell, the cut off takes place before the pack is finished. If it it is too low, below .8V per cell, you risk the the chance that the cell could reverse. Nicads and NIMH's cells are pretty durable but not immune to damage.

Evan Chapkis
RC Accessory, Inc.
Auth US Bantam Importer
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Old Jan 14, 2007, 06:41 AM
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Huntsville, Texas USA
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Thanks for the informative answers. I was mainly refering to Sanyo 1100MaH flight packs in my planes.

Thanks Again!
Bud
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Old Jan 14, 2007, 07:22 AM
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Quote:
Originally Posted by GoLikeaFish
What about brand new? I've been told to cycle the batteries 10 times before using for the first time.
I don't know who told you that but it seems like you'd be doing away w' 10-20% of the best usage.

I bought 6 packs and cycled the first three per the instructions. 25% of the c rating for first 3 cycles. The other 3 I charged at 1c and flew. Guess which ones "died" first. It was the first three.

Like i said earlier though I'd charge/ cycle new ones at half c for 2-3 cycles max and then charge at 1c thereafter. If they seem to get weak from storage or use the go ahead and repeat the cycle process. Sometimes it helps and sometimes it don't.
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Old Jan 14, 2007, 08:35 AM
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I have heard the "cycle new packs x number of times" , and buy a lot of unmatched/unzapped packs. I sometimes will slow charge and run a discharge test on a new pack, but have noticed on any of my packs that the very first cycle is the best capacity/voltage. 10% of the time it is the second or third cycle.

Most of mine are new gp 3300 and generic 3000 cells or generic AA cells. I am confidant to slow charge 1 time and then put them to whatever use. Occasionally I will use a lower voltage pack in a new model to breakin the motor, battery and allow me to get used to how stuff handles and set radio up. After 1 or 2 runs I'm ready to "cell up, gear up or motor up to full speed"
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Old Jan 14, 2007, 10:19 AM
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Check out http://members.aol.com/davthacker/balancecharging.htm for some good advice on the care of your batteries and the value of occasional slow charges.
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Old Jan 14, 2007, 12:37 PM
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The BA
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I have 1500mah batteries and a Triton Jr that will charge at either .1 or .2 amps. Which setting should I use for the formation charge?
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Old Jan 14, 2007, 12:43 PM
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If I remember, the Triton Jr has a 2 hours non adjustable time cut off. If correct, you will not be able to use a Triton Jr for a formation charge. It could be for lipo only, I would have to refer to Red's comments online as well in his magazine column.
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Old Jan 14, 2007, 01:33 PM
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Quote:
Originally Posted by RC Accessory
If I remember, the Triton Jr has a 2 hours non adjustable time cut off. If correct, you will not be able to use a Triton Jr for a formation charge. It could be for lipo only, I would have to refer to Red's comments online as well in his magazine column.
You're correct. Given that, the minimum I can charge at is .8A.
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